1, blank.bmp
"Basal Metabolic Rate (BMR) is measured while the subject is asleep."
"F"
"BMR must be measured while the subject is awake, but completely at rest, because some people show an increase in metabolic rate while asleep, and others a decrease."
"Basal Metabolic Rate (BMR) is measured with the subject completely at rest but awake."
"T"
"BMR must be measured while the subject is awake, but completely at rest, because some people show an increase in metabolic rate while asleep, and others a decrease." 
2, blank.bmp
"Basal Metabolic Rate (BMR) can be determined by measuring oxygen consumption."
"T"
"There is a constant 20 kJ energy expenditure per L of oxygen consumed, regardless of the fuel being oxidized, so measurement of oxygen consumption provides an indirect measurement of energy expenditure. If the subject is completely at rest, and the experiment is conducted under standardized conditions, then what is measured is BMR."
"Basal Metabolic Rate (BMR) can be determined by measuring the heat output from the body."
"T"
"Energy expenditure can indeed be measured directly, as heat output from the body. If the subject is completely at rest, and the experiment is conducted under standardized conditions, then what is measured is BMR." 
3, blank.bmp
"The energy cost of physical activity can be determined by measuring oxygen consumption."
"T"
 "There is a constant 20 kJ energy expenditure per L of oxygen consumed, regardless of the fuel being oxidized, so measurement of oxygen consumption provides an indirect measurement of energy expenditure."
"The energy cost of physical activity can be determined by measuring heat output from the body."
"T"
"Energy expenditure can indeed be measured directly, as heat output from the body." 
4, blank.bmp
"The energy cost of physical activity can be determined by measuring carbon dioxide production during the activity."
"F"
"There is a constant amount of energy expenditure per L of oxygen consumed, but the amount of carbon dioxide produced per L of oxygen consumed depends on the mixture of fuels being oxidized. Simple measurement of carbon dioxide production will not permit estimation of energy expenditure over a short time."
"The energy cost of physical activity can be determined by measuring respiratory quotient (RQ) production during the activity."
"F"
"There is a constant amount of energy expenditure per L of oxygen consumed, but the RQ (the amount of carbon dioxide produced per L of oxygen consumed) depends on the mixture of fuels being oxidized. Simple measurement of RQ will not permit estimation of energy expenditure over a short time." 
5, blank.bmp
"BMR (Basal Metabolic Rate) is the energy expenditure by the body at rest, measured under standardized conditions."
"T"
"This is the definition of BMR - energy expenditure awake, but completely at rest, and under standardized conditions of thermal neutrality."
"In order to measure BMR (Basal Metabolic Rate), the subject must be under conditions of thermal neutrality."
"T"
"The subject must not be expending energy in order to keep warm or cool down, so s/he must be maintained under conditions of thermal neutrality for measurement of BMR." 
6, blank.bmp
"Resting Metabolic Rate (RMR) is the energy expenditure of the body at rest, but not measured under conditions of strictly controlled temperature."
"T"
"RMR is effectively the same as BMR (Basal Metabolic Rate), but the measurement is not made under conditions of thermal neutrality."
"Resting Metabolic Rate (RMR) is the energy expenditure of the body when asleep."
"F"
"RMR is effectively the same as BMR (Basal Metabolic Rate), but the measurement is not made under conditions of thermal neutrality. The subject must be completely at rest, but awake, because some people show an increase in metabolic rate while asleep, and others a decrease." 
7, blank.bmp
"Physical Activity Ratio (PAR) is the energy cost of physical activity expressed as a multiple of BMR (Basal Metabolic Rate)."
"T"
"Expressing the energy cost of activity as a multiple of BMR in this way permits comparison of people of different body size and with different BMR."
"Physical Activity Ratio (PAR) is the energy cost of physical activity throughout the day."
"F"
"Physical Activity Ratio (PAR) is the energy cost of physical activity expressed as a multiple of BMR (Basal Metabolic Rate)." 
8, blank.bmp
"Physical Activity Level (PAL) is the energy cost of physical activity expressed as a multiple of BMR (basal metabolic rate)."
"F"
"Physical activity level (PAL) is the sum of Physical Activity Ratios for different activities throughout the day, multiplied by the time spent in each activity, expressed as a multiple of BMR."
"Physical activity level (PAL) is the sum of Physical Activity Ratios for different activities throughout the day, multiplied by the time spent in each activity, expressed as a multiple of BMR."
"T"
"Expressing the energy cost of activity as a multiple of BMR in this way permits comparison of people of different body size and with different BMR." 
9, blank.bmp
"Basal Metabolic Rate (BMR) depends on body weight and physical activity."
"F"
"BMR is measured at rest, so physical activity is not relevant. BMR does indeed depend on body weight."
"Basal Metabolic Rate (BMR) depends on body weight."
"T"
"BMR is the energy cost of maintaining physical and chemical homeostasis in the body, so it does indeed depend on body weight." 
10, blank.bmp
"Basal Metabolic Rate (BMR) depends on body weight and body fat content."
"T"
"Although adipose tissue is mainly triacylglycerol, it is still metabolically active, and therefore makes a small contribution to BMR."
"Adipose tissue does not contribute to Basal Metabolic Rate (BMR.)
"F"
"Although adipose tissue is mainly triacylglycerol, it is still metabolically active, and therefore makes a small contribution to BMR." 
11, blank.bmp
"Women have a lower BMR (Basal Metabolic Rate) than men of the same body weight because they have a greater proportion of lean tissue."
"F"
"Women have a greater proportion of body weight as adipose tissue, and therefore a lower proportion as lean tissue, than do men. Adipose tissue makes a smaller contribution to BMR than do muscle and other tissues."
"Women have a lower BMR (Basal Metabolic Rate) than men of the same body weight because they have a greater proportion of adipose tissue."
"T"
"Women have a greater proportion of body weight as adipose tissue, and therefore a lower proportion as lean tissue, than do men. Adipose tissue makes a smaller contribution to BMR than do muscle and other tissues." 
12, blank.bmp
"BMR (Basal Metabolic Rate) decreases with age, even if weight remains constant, because older people have a greater proportion of adipose tissue than do younger people."
"T"
"Older people have a greater proportion of body weight as adipose tissue, and therefore a lower proportion as lean tissue, than do younger people. Adipose tissue makes a smaller contribution to BMR than do muscle and other tissues."
"BMR (Basal Metabolic Rate) decreases with age, even if weight remains constant, because older people have a greater proportion of lean tissue than do younger people."
"F"
"Older people have a greater proportion of body weight as adipose tissue, and therefore a lower proportion as lean tissue, than do younger people. Adipose tissue makes a smaller contribution to BMR than do muscle and other tissues." 
13, blank.bmp
"The Physical Activity Ratio (PAR) for a given activity depends on the time spent in the activity."
"F"
"PAR is the energy cost of an activity expressed as a multiple of Basal Metabolic Rate (BMR), and is therefore independent of time."
"The Physical Activity Ratio (PAR) for a given activity depends on the subject's Basal Metabolic Rate (BMR)."
"F"
"PAR is the energy cost of an activity expressed as a multiple of the subject's Basal Metabolic Rate (BMR), and is therefore independent the value of his or her BMR." 
14, blank.bmp
"The Physical Activity Ratio (PAR) for a given activity depends on the subject's body weight."
"T"
"The energy cost of moving a heavier body is greater, so the energy cost of physical activity increases with body weight. Although Basal Metabolic Rate (BMR) also increases with increasing body weight, this is a smaller increase than the increase in the energy cost of activity. PAR is the energy cost of activity expressed as a multiple of BMR, so PAR for a given activity increases with increasing body weight."
"The Physical Activity Ratio (PAR) for a given activity does not depend on the subject's body weight."
"F"
"The energy cost of moving a heavier body is greater, so the energy cost of physical activity increases with body weight. Although Basal Metabolic Rate (BMR) also increases with increasing body weight, this is a smaller increase than the increase in the energy cost of activity. PAR is the energy cost of activity expressed as a multiple of BMR, so PAR for a given activity increases with increasing body weight." 
15, blank.bmp
"There is an increase in metabolic rate after a meal because of the synthesis of metabolic fuel reserves."
"T"
"This so-called diet-induced thermogenesis may amount to 10% or more of the energy yield of a meal, because of the high energy cost of synthesizing tissues reserves of glycogen, triacylglycerol and protein."
"There is a decrease in metabolic rate after a meal because of the synthesis of metabolic fuel reserves."
"F"
"There is an increase in metabolic rate after a meal. This is diet-induced thermogenesis; it may amount to 10% or more of the energy yield of a meal, because of the high energy cost of synthesizing tissues reserves of glycogen, triacylglycerol and protein." 
16, blank.bmp
"Energy balance is the difference between energy intake in food and energy expenditure."
"T"
"This is the definition of a metabolic balance - the simple difference between intake and output."
"Energy balance is the ratio of energy intake from food / energy expenditure."
"F"
"Energy balance is the difference between energy intake in food and energy expenditure. This is the definition of any metabolic balance - the simple difference between intake and output." 
17, wtgain.bmp
"The blue line shows the theoretical weight gain for a subject whose energy intake is greater than energy expenditure. This subject will be in negative energy balance."
"F"
"Energy balance is the difference between energy intake in food and energy expenditure; a negative balance means that intake is less than expenditure - this subject is in positive balance and is gaining body weight."
"The blue line shows the theoretical weight gain for a subject whose energy intake is greater than energy expenditure. This subject will be in positive energy balance."
"T"
"Energy balance is the difference between energy intake in food and energy expenditure; a positive balance means that intake is greater than expenditure - this subject is indeed in positive balance and is gaining body weight." 
18, wtloss.bmp
"The blue line shows the theoretical weight loss for a subject whose energy intake is less than energy expenditure. This subject will be in negative energy balance."
"T"
"Energy balance is the difference between energy intake in food and energy expenditure; a negative balance means that intake is less than expenditure - this subject is indeed in negative balance and is losing body weight."
"The blue line shows the theoretical weight loss for a subject whose energy intake is less than energy expenditure. This subject will be in positive energy balance."
"F"
"Energy balance is the difference between energy intake in food and energy expenditure; a negative balance means that intake is less than expenditure - this subject is in negative balance and is losing body weight." 
19, wtgain.bmp
"Adipose tissue consists of 80% triacylglycerol (37 kJ /g) and 15% protein (17 kJ /g). This means that you can calculate a theoretical gain in body weight (as adipose tissue) of 33 g /MJ excess intake / day."
"T"
"This is a theoretical maximum rate of gain of adipose tissue, and ignores the cost of synthesizing the triacylglycerol for storage."
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is that as more food is eaten so there is a greater energy cost of synthesizing adipose tissue triacylglycerol."
"T"
"As more food is eaten, so there is a greater cost of storing the excess, mainly as triacylglycerol." 
20, wtgain.bmp
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is that protein synthesis increases when there is an abundant supply of metabolic fuel."
"T"
"Protein synthesis is energy-expensive, and as energy intake increases, so there is an increased rate of protein synthesis."
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is that protein synthesis decreases when there is an abundant supply of metabolic fuel."
"F"
"Protein synthesis is energy-expensive, and as energy intake increases, so there is an increased rate of protein synthesis." 
21, wtgain.bmp
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is that Basal Metabolic Rate (BMR) increases with increasing body weight, so there is a greater requirement for energy for maintenance."
"T"
"BMR does indeed increase with increasing body weight, and therefore a person with a heavier body will have a higher energy requirement, not only for maintenance, but also because the energy cost of physical activity increases with increasing BMR." 
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is that Basal Metabolic Rate (BMR) decreases with increasing body weight, so there is a lesser requirement for energy for maintenance."
"F"
"BMR increases with increasing body weight, and therefore a person with a heavier body will have a higher energy requirement, not only for maintenance, but also because the energy cost of physical activity increases with increasing BMR."  
22, wtgain.bmp
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is as body weight increases so there is a greater energy cost of physical activity."
"T"
"As body weight increases, so the energy cost of moving the body increases. This means that a heavier person has a greater energy requirement for the same level of physical activity than a lighter person."
"The blue line shows the theoretical weight gain for a subject who is consuming more energy from food than his/her energy expenditure. The red line shows the observed weight gain over several weeks. Part of the explanation for the difference is as body weight increases so there is a lower energy cost of physical activity."
"F"
"As body weight increases, so the energy cost of moving the body increases. This means that a heavier person has a greater energy requirement for the same level of physical activity than a lighter person." 
23, wtloss.bmp
"The blue line shows the theoretical weight loss for a subject who is consuming less energy from food than his/her energy expenditure. The red line shows the observed weight loss over several weeks. Part of the explanation for the difference is as body weight decreases so there is a lower energy cost of physical activity."
"T"
"As body weight decreases, so the energy cost of moving the body decreases. This means that a lighter person has a lower energy requirement for the same level of physical activity than a heavier person."
"The blue line shows the theoretical weight loss for a subject who is consuming less energy from food than his/her energy expenditure. The red line shows the observed weight loss over several weeks. Part of the explanation for the difference is as body weight decreases so there is a greater energy cost of physical activity."
"F"
"As body weight decreases, so the energy cost of moving the body decreases. This means that a lighter person has a lower energy requirement for the same level of physical activity than a heavier person." 
24, wtloss.bmp
"The blue line shows the theoretical weight loss for a subject who is consuming less energy from food than his/her energy expenditure. The red line shows the observed weight loss over several weeks. Part of the explanation for the difference is as body weight decreases the Basal Metabolic Rate (BMR) falls."
"T"
"BMR decreases with decreasing body weight, and therefore a person with a lighter body will have a lower energy requirement, not only for maintenance, but also because the energy cost of physical activity decreases with decreasing BMR." 
"The blue line shows the theoretical weight loss for a subject who is consuming less energy from food than his/her energy expenditure. The red line shows the observed weight loss over several weeks. Part of the explanation for the difference is as body weight decreases the Basal Metabolic Rate (BMR) increases."
"F"
"BMR decreases with decreasing body weight, and therefore a person with a lighter body will have a lower energy requirement, not only for maintenance, but also because the energy cost of physical activity decreases with decreasing BMR."  
25, fed.bmp
"In the fed state there is increased secretion of insulin in response to increased glucose in the portal blood."
"T"
"Insulin is the hormone of the fed state. It is secreted in response to an increased concentration of glucose in the hepatic portal vein, coming from the gastro-intestinal tract."
"In the fed state there is decreased secretion of insulin in response to increased glucose in the portal blood."
"F"
"Insulin is the hormone of the fed state. It is secreted in response to an increased concentration of glucose in the hepatic portal vein, coming from the gastro-intestinal tract." 
26, fed.bmp
"In the fed state there is increased secretion of glucagon in response to increased glucose in the portal blood."
"F"
"Insulin is the hormone of the fed state. It is secreted in response to an increased concentration of glucose in the hepatic portal vein, coming from the gastro-intestinal tract."
"In the fed state there is decreased secretion of glucagon in response to increased glucose in the portal blood."
"T"
"Glucagon is secreted in the fasting state when there is a lower concentration of glucose in the hepatic portal vein. Insulin is the hormone of the fed state, and acts to reduce the secretion of glucagon." 
27, fast.bmp
"In the fasting state there is increased secretion of glucagon in response to decreased glucose in the portal blood."
"T"
"As the concentration of glucose in the hepatic portal vein falls, so insulin secretion falls, and glucagon secretion increases."
"In the fasting state there is decreased secretion of glucagon in response to decreased glucose in the portal blood."
"F"
"As the concentration of glucose in the hepatic portal vein falls, so insulin secretion falls, and glucagon secretion increases."
28, fast.bmp
"In the fasting state there is increased secretion of insulin in response to decreased glucose in the portal blood."
"F"
"Insulin is the hormone of the fed state. It is secreted in response to an increased concentration of glucose in the hepatic portal vein, coming from the gastro-intestinal tract. In the fasting state, as the concentration of glucose in the hepatic portal vein falls, so insulin secretion falls and glucagon secretion increases."
"In the fasting state there is decreased secretion of insulin in response to decreased glucose in the portal blood."
"T"
"Insulin is the hormone of the fed state. It is secreted in response to an increased concentration of glucose in the hepatic portal vein, coming from the gastro-intestinal tract. In the fasting state, as the concentration of glucose in the hepatic portal vein falls, so insulin secretion falls and glucagon secretion increases." 
29, fed.bmp.
"In the fed state, insulin acts to increase the synthesis of glycogen from glucose."
"T"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal."
"In the fed state, glucagon acts to increase the synthesis of glycogen from glucose."
"F"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal." 
30, fed.bmp.
"In the fed state, insulin acts to increase the synthesis of protein from amino acids."
"T"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal."
"In the fed state, glucagon acts to increase the synthesis of protein from amino acids."
"F"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal." 
31, fed.bmp.
"In the fed state, insulin acts to increase the synthesis of triacylglycerol."
"T"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal."
"In the fed state, glucagon acts to increase the synthesis of triacylglycerol."
"F"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal." 
32, fed.bmp
"In the fed state insulin acts to increase the breakdown of glycogen to maintain blood glucose."
"F"
"Insulin acts to increase the synthesis of glycogen, and decrease its breakdown; it is glucagon, secreted in the fasting state, that acts to increase the breakdown of glycogen."
"In the fed state glucagon acts to increase the breakdown of glycogen to maintain blood glucose."
"F"
"Glucagon is secreted in the fasting state, not the fed state. In the fed state insulin acts to increase the synthesis of glycogen and decrease its breakdown." 
33, fast.bmp.
"In the fasting state, insulin acts to increase the synthesis of glycogen from glucose."
"F"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal. It is glucagon, secreted in the fasting state, that acts to increase the breakdown of glycogen."
"In the fasting state, glucagon acts to increase the synthesis of glycogen from glucose."
"F"
"Glucagon is secreted in the fasting state and acts to increase the breakdown of glycogen." 
34, fast.bmp
"In the fasting state insulin acts to increase the breakdown of glycogen to maintain blood glucose."
"F"
"Insulin acts to increase the synthesis of glycogen, and decrease its breakdown; it is glucagon, secreted in the fasting state, that acts to increase the breakdown of glycogen."
"In the fasting state glucagon acts to increase the breakdown of glycogen to maintain blood glucose."
"T"
"Glucagon is secreted in the fasting state and acts to increase the breakdown of glycogen." 
35, fuels.bmp
"In the fasting state the main metabolic fuel for most tissues comes from fatty acids released from adipose tissue."
"T"
"Apart from tissues that are more or less completely reliant on glucose as their fuel, most tissues use fatty acids from adipose tissue reserves in the fasting state."
"In the fed state the main metabolic fuel for most tissues is glucose."
"T"
"When there is an abundant supply of glucose it is the main fuel for most tissues." 
36, fuels.bmp
"In the fed state muscle can take up glucose for use as a metabolic fuel because glucose transport in muscle is stimulated in response to insulin."
"T"
"Insulin acts to recruit glucose transporters to the cell surface in muscle and adipose tissue, so that in the presence of insulin they can take up and metabolize glucose."
"In the fed state muscle can take up glucose for use as a metabolic fuel because glucose transport in muscle is stimulated in response to glucagon."
"F"
"Glucagon is secreted in the fasting state. Insulin is secreted in the fed state and acts to recruit glucose transporters to the cell surface in muscle and adipose tissue, so that in the presence of insulin they can take up and metabolize glucose." 
37, fuels.bmp
"In the fed state adipose can take up glucose for synthesis of triacylglycerol because glucose transport in adipose tissue is stimulated in response to insulin."
"T"
"Insulin acts to recruit glucose transporters to the cell surface in muscle and adipose tissue, so that in the presence of insulin they can take up and metabolize glucose."
"In the fed state adipose can take up glucose for synthesis of triacylglycerol because glucose transport in adipose tissue is stimulated in response to glucagon."
"T"
"Glucagon is secreted in the fasting state. Insulin is secreted in the fed state and acts to recruit glucose transporters to the cell surface in muscle and adipose tissue, so that in the presence of insulin they can take up and metabolize glucose." 
38, fuels.bmp
"Ketone bodies are synthesized in muscle in the fasting state, and the amount synthesized increases as fasting extends into starvation."
"F"
"Ketone bodies are synthesized in the liver, and are exported to muscle and other tissues in the fasting state."
"Ketone bodies are synthesized in liver in the fasting state, and the amount synthesized increases as fasting extends into starvation."
"T"
"Ketone bodies are synthesized in the liver, and are exported to muscle and other tissues in the fasting state for use as a metabolic fuel, so as to spare glucose for tissues that are more or less completely reliant on glucose." 
39, fuels.bmp
"Plasma glucose is maintained in starvation and prolonged fasting by breakdown of liver glycogen reserves."
"F"
"Liver and muscle glycogen together would only meet glucose needs in fasting for about 18 hours. As fasting is prolonged, so increasingly glucose is synthesized by gluconeogenesis from amino acids and the glycerol of triacylglycerols."
"Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from amino acids."
"T"
"Liver and muscle glycogen together would only meet glucose needs in fasting for about 18 hours. As fasting is prolonged, so increasingly glucose is synthesized by gluconeogenesis from amino acids and the glycerol of triacylglycerols." 
40, fuels.bmp
"Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from fatty acids."
 "F"
"Fatty acids can never be a substrate for gluconeogenesis."
"Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from ketone bodies."
"F"
"Ketone bodies can never be a substrate for gluconeogenesis." 
41, fuels.bmp
"Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from the glycerol released from adipose tissue triacylglycerol."
"T"
"Glycerol can be substrate for gluconeogenesis. However, the fatty acids from triacylglycerol can never be a substrate for gluconeogenesis."
 "Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from the amino acids released by the breakdown of muscle protein."
"T"
"Liver and muscle glycogen together would only meet glucose needs in fasting for about 18 hours. As fasting is prolonged, so increasingly glucose is synthesized by gluconeogenesis from amino acids and the glycerol of triacylglycerols." 
42, blank.bmp
"There is an increase in metabolic rate in the fed state."
"T"
"In the fed state there is a considerable increase in metabolic rate, as a result of the energy cost of synthesizing tissue reserves of glycogen, triacylglycerol and protein. This diet-induced thermogenesis may account for 10% of the energy yield of a meal."
"There is an increase in metabolic rate in the fasting state."
"F"
"Energy expenditure falls in the fasting state. In the fed state there is a considerable increase in metabolic rate, as a result of the energy cost of synthesizing tissue reserves of glycogen, triacylglycerol and protein." 
43, fuels.bmp
"Fatty acids and triacylglycerol are synthesized in adipose tissue in the fasting state."
"F"
"In the fasting state triacylglycerol is hydrolysed to release fatty acids for use as a metabolic fuel, and fatty acid synthesis is inhibited."
"Fatty acids and triacylglycerol are synthesized in adipose tissue in the fed state."
"T"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal." 
44, fuels.bmp
"Fatty acids and triacylglycerol are synthesized in the liver in the fasting state."
"F"
"In the fasting state triacylglycerol and fatty acid synthesis are inhibited."
"Fatty acids and triacylglycerol are synthesized in the liver in the fed state."
"T"
"Insulin is the hormone of the fed state; its main actions are to increase the synthesis of tissue reserves of glycogen, triacylglycerol and protein when there is an abundant supply of metabolic fuels coming from a meal." 
45, fuels.bmp
"Ketone bodies provide the main fuel for the central nervous system in the fasting state."
"F"
"Although the central nervous system can use ketone bodies as a metabolic fuel, they cannot account for more than a small percentage of total nervous system energy requirements."
"Ketone bodies provide the main fuel for red blood cells in the fasting state."
"F"
"Red blood cells lack mitochondria, and therefore can never metabolize fatty acids or ketone bodies; they are completely reliant on glucose as their metabolic fuel at all times." 
46, fast.bmp
"In the fasting state the kidneys synthesize glucose from amino acids."
"T"
"Liver and muscle glycogen together would only meet glucose needs in fasting for about 18 hours. As fasting is prolonged, so increasingly glucose is synthesized by gluconeogenesis from amino acids in the liver, kidneys and intestinal mucosal cells."
"In the fasting state muscle synthesizes glucose from amino acids."
"F"
"Muscle does not have the enzymes required for gluconeogenesis. It releases amino acids from the breakdown of muscle protein that are used by the liver, kidneys and intestinal mucosal cells as substrates for gluconeogenesis." 
47, fuels.bmp
"In the fasting state adipose tissue synthesizes ketone bodies." 
"F"
"Adipose tissue releases fatty acids in the fasting state; these are used in the liver for synthesis of ketone bodies."
"In the fasting state adipose tissue synthesizes glucose from the glycerol released by the breakdown of triacylglycerol."
"F"
"Adipose tissue lacks the enzymes required for gluconeogenesis; it exports the glycerol released by the breakdown of triacylglycerol to the liver, where it is a substrate for gluconeogenesis." 
48, fuels.bmp
"In the fasting state the main fuel for the central nervous system is fatty acids released from adipose tissue."
"F"
"The central nervous system has a very limited capacity for the oxidation of fatty acids, and they can never provide more than a small proportion of energy needs. The main fuel of the central nervous system is glucose under all conditions."
"In the fasting state the main fuel for red blood cells is fatty acids released from adipose tissue."
"F"
"Red blood cells lack mitochondria, and therefore can never metabolize fatty acids or ketone bodies; they are completely reliant on glucose as their metabolic fuel at all times." 
49, glycol1.bmp
"If hexokinase and glucose 6-phosphatase are both equally active at the same time there is a nett formation of ATP from ADP and phosphate."
"F"
"With both enzymes equally active at the same time there will be nett hydrolysis of ATP to yield ADP and phosphate."
"If hexokinase and glucose 6-phosphatase are both equally active at the same time there is a nett loss of ATP and in increase in heat output from the body."
"T"
"This is a so-called 'futile cycle' or substrate cycle, and these two enzymes are regulated in such a way that only one has significant activity at any time. However, there is always some cycling between the two enzymes, both to maintain body temperature and also to permit rapid metabolic regulation." 
50, glycol2.bmp
"If phosphofructokinase and fructose 1,6-bisphosphatase are both equally active at the same time there is a nett formation of ATP from ADP and phosphate."
"F"
"With both enzymes equally active at the same time there will be nett hydrolysis of ATP to yield ADP and phosphate."
"If phosphofructokinase and fructose 1,6-bisphosphatase are both equally active at the same time there is a nett loss of ATP and in increase in heat output from the body."
"T"
"This is a so-called 'futile cycle' or substrate cycle, and these two enzymes are regulated in such a way that only one has significant activity at any time. However, there is always some cycling between the two enzymes, both to maintain body temperature and also to permit rapid metabolic regulation." 
51, glycol1.bmp
"Glucose 6-phosphatase is especially important in the liver in the fed state."
"F"
"The hydrolysis of glucose 6-phosphate is important in liver in the fasting state to maintain the blood glucose concentration."
"Glucose 6-phosphatase is especially important in the liver in the fasting state."
"T"
"The hydrolysis of glucose 6-phosphate arising from glycogen breakdown and gluconeogenesis is important in liver in the fasting state to maintain the blood glucose concentration." 
52, glycol1.bmp
"Glucose 6-phosphatase is especially important in muscle in the fed state."
"F"
"Muscle does not contain glucose 6-phosphatase."
"Glucose 6-phosphatase is especially important in muscle in the fasting state."
"F"
"Muscle does not contain glucose 6-phosphatase." 
53, glycol1.bmp
"Hexokinase is important in liver in the fed state"
"T"
"The phosphorylation of glucose to glucose 6-phosphate is essential for both glycolysis and glycogen synthesis in the fed state."
"Liver contains an isoenzyme of hexokinase, glucokinase, which is especially important in the fed state."
"T"
"Hexokinase has a low Km, and is saturated, and hence acting at Vmax, well below the normal intracellular concentration of glucose in the liver. Glucokinase has a high Km, and only becomes significantly active when the concentration of glucose entering the liver is high, as in the fed state. This additional glucose is then used for synthesis of glycogen." 
54, glycol2.bmp
 "Phosphofructokinase is especially important in the liver in the fed state."
"T"
"This is one of the key regulated steps of glycolysis, and it will be active in liver and other tissues in the fed state when glucose is the major metabolic fuel."
"Phosphofructokinase is especially important in the liver in the fasting state."
"F"
"This is one of the key regulated steps of glycolysis, and will be important in liver and other tissues in the fed state when glucose is the major metabolic fuel. In the fasting state its activity is reduced, and that of fructose 1,6-bisphosphatase increased, to permit gluconeogenesis." 
55, glycol2.bmp
 "Fructose 1,6-bisphosphatase is especially important in the liver in the fasting state."
"T"
"This is one of the key regulated steps of glucose metabolism, and it will be active in liver in the fasting state when gluconeogenesis is occurring."
"Fructose 1,6-bisphosphatase is especially important in the liver in the fed state."
"F"
"This is one of the key regulated steps of glucose metabolism, and it will be relatively inactive in liver in the fed state when glucose is the major metabolic fuel, and glycolysis is occurring." 
56, overview.bmp
 "Glycolysis occurs in the cytosol. "
"T"
"Glycolysis is a cytosolic pathway; the NADH formed in glycolysis cannot enter the mitochondria directly, but must use substrate shuttles to transfer reducing equivalents into the mitochondria for electron transport and ATP formation."
"Glycolysis occurs in the mitochondria."
"F"
"Glycolysis is a cytosolic pathway; the NADH formed in glycolysis cannot enter the mitochondria directly, but must use substrate shuttles to transfer reducing equivalents into the mitochondria for electron transport and ATP formation." 
57, cori.bmp
"Glycolysis can proceed in the absence of oxygen only if lactate is formed from pyruvate. "
"T"
"Reduction of pyruvate to lactate permits re-oxidation, and hence recycling, of NADH. Under normal conditions the NADH is re-oxidized (indirectly) by mitochondrial oxidation, using oxygen. This cannot occur in the absence of oxygen."
"The reverse of glycolysis is the pathway for gluconeogenesis in skeletal muscle."
"F"
"Gluconeogenesis does not occur in skeletal muscle."  
58, G6Psource.bmp
"There is a nett yield of 3 ATP per 2 mol lactate formed from glycogen under anaerobic conditions."
"T"
"When glycogen is the initial substrate, glucose 1-phosphate (which in interconvertible with glucose 6-phosphate) is formed by phosphorolysis using inorganic phosphate, rather than phosphorylation using ATP, as occurs when glucose is the initial substrate."
"There is a nett yield of 2 ATP per 2 mol lactate formed from glucose under anaerobic conditions."
"T"
"When glucose is the initial substrate ATP is required to form glucose 6-phosphate for glycolysis." 
59, cori.bmp
"Glycolysis can proceed in the absence of oxygen only if pyruvate is formed from lactate in muscle."
"F"
"Under anaerobic conditions pyruvate is reduced to lactate, which is exported from muscle."
"Glycolysis can proceed in the absence of oxygen only if lactate is formed from pyruvate in muscle."
"T"
"Under anaerobic conditions pyruvate is reduced to lactate, which is exported from muscle." 
60, blank.bmp
"A number of the enzymes in glycolysis catalyse irreversible reactions."
"T"
"This means that these steps are catalysed by different enzymes in glycolysis and gluconeogenesis, so permitting regulation of glycolysis versus gluconeogenesis."
"All the reactions of glycolysis are freely reversible for gluconeogenesis."
"F"
"Three steps in glycolysis are catalysed by enzymes that are essentially irreversible. This means that these steps are catalysed by different enzymes in glycolysis and gluconeogenesis, so permitting regulation of glycolysis versus gluconeogenesis."
61, blank.bmp
"Fructose can be used for gluconeogenesis in the liver because it can be phosphorylated to fructose 6-phosphate."
"T"
"Fructose is phosphorylated to fructose 6-phosphate by hexokinase to a limited extent, and also by fructokinase."
"Fructose cannot be used for gluconeogenesis in the liver because it cannot be phosphorylated to fructose 6-phosphate."
"F"
"Fructose is phosphorylated to fructose 6-phosphate by hexokinase to a limited extent, and also by fructokinase." 
62, cori.bmp
"Glycolysis can never proceed in the absence of oxygen."
"F"
"As long as NAD is recycled, by reducing pyruvate to lactate, glycolysis can occur under anaerobic conditions."
"Red blood cells only metabolize glucose by anaerobic glycolysis (and the pentose phosphate pathway)."
"T"
"Red blood cells have no mitochondria, and therefore can only metabolize glucose anaerobically. They recycle NAD by reducing pyruvate to lactate, which is exported to the liver for gluconeogenesis." 
63, glycol1.bmp
"Muscle can release glucose into the circulation from its glycogen reserves in the fasting state."
"F"
"Muscle lacks glucose 6-phosphatase, and cannot release glucose into the circulation under any conditions."
"Muscle cannot release glucose into the circulation from its glycogen reserves in the fasting state."
"T"
"Muscle lacks glucose 6-phosphatase, and cannot release glucose into the circulation under any conditions." 
 63, glycol1.bmp
"Because hexokinase has a low Km it normally acts at a constant rate, in liver."
"T"
"In liver the intracellular concentration of glucose will always be considerably above the Km of hexokinase, so it will act at or near its Vmax. However, in muscle the intracellular concentration of glucose is controlled by the rate of uptake of glucose into the cell, and the activity of the glucose transporter in muscle is regulated by insulin. Except in the fed state, the intracellular concentration of glucose in muscle will be relatively low, and hexokinase will not have very great activity."
"Because hexokinase has a low Km its activity in liver increases as the concentration of glucose in the portal blood increases."
"F"
"In liver the intracellular concentration of glucose will always be considerably above the Km of hexokinase, so it will act at or near its Vmax. However, in muscle the intracellular concentration of glucose is controlled by the rate of uptake of glucose into the cell, and the activity of the glucose transporter in muscle is regulated by insulin. Except in the fed state, the intracellular concentration of glucose in muscle will be relatively low, and hexokinase will not have very great activity."  
64, cori.bmp
"In maximum exertion muscle is partially anaerobic."
"T"
"Under conditions of maximum exertion the rate of metabolism is greater than the ability of muscle to take up oxygen, so while there will be as much aerobic metabolism as possible, there will also be a considerable amount of anaerobic glycolysis."
"In maximum exertion pyruvate is oxidized to lactate in muscle."
"F"
"Pyruvate is reduced to lactate." 
65, cori.bmp
"Gluconeogenesis from lactate requires less ATP than is formed during anaerobic glycolysis."
"F"
"Gluconeogenesis requires more ATP than is formed in glycolysis. It is the need to oxidize additional metabolic fuel to provide this ATP that leads to the phenomenon of oxygen debt after vigorous activity."
"There is acidosis as a result of vigorous exercise."
"T"
"This is the result of release from muscle of large amounts of lactate, which is an acid." 
66, cori.bmp
"Oxygen debt is caused by the need to exhale carbon dioxide produced in response to acidosis."
"F"
"Oxygen debt represents the increased metabolic activity to provide the ATP required for gluconeogenesis from lactate after vigorous exercise."
"Oxygen debt reflects the need to replace oxygen that has been used in muscle during vigorous exercise."
"F"
"Oxygen debt represents the increased metabolic activity to provide the ATP required for gluconeogenesis from lactate after vigorous exercise." 
67, cori.bmp
"In maximum exertion pyruvate is reduced to lactate in muscle."
"T"
"The reduction of pyruvate to lactate permits recycling of NAD under anaerobic conditions, so that glycolysis can continue."
"Most of the lactate released from muscle under anaerobic conditions is used for gluconeogenesis in the liver."
"T"
"A proportion will be oxidized carbon dioxide and water, to provide the ATP required for gluconeogenesis."  
68, glycol5.bmp
"Pyruvate kinase is an important reaction in gluconeogenesis, forming phospho-enolpyruvate from pyruvate."
"F"
"Pyruvate kinase catalyses the essentially irreversible reaction from phospho-enolpyruvate to pyruvate, linked to phosphorylation of ADP to ATP."
"Reversal of the reaction catalysed by pyruvate kinase for gluconeogenesis involved two enzyme-catalysed reactions."
"T"
"Pyruvate is carboxylated to oxaloacetate by pyruvate carboxylase; oxaloacetate is then decarboxylated and phosphorylated to phospho-enolpyruvate by phospho-enolpyruvate carboxykinase." 
69, glycol4.bmp
"The reaction of glyceraldehyde 3-phosphate dehydrogenase is a substrate-level phosphorylation."
"F"
"Although this reaction involves incorporation of inorganic phosphate into an organic molecule, this is not substrate-level phosphorylation, which means the phosphorylation of ADP to ATP at the expense of another phosphorylated substrate. In this diagram the reaction of phosphoglycerate kinase represents (in the direction of glycolysis) a substrate-level phosphorylation."
"The reaction of phosphoglycerate kinase is a substrate-level phosphorylation.
"T"
"Substrate-level phosphorylation is the phosphorylation of ADP to ATP at the expense of another phosphorylated substrate; in the direction of glycolysis is indeed a substrate-level phosphorylation" 
70, glycol5.bmp
 "Pyruvate carboxylase is an important source of oxaloacetate to maintain citric acid cycle activity."
"T"
"This is one of the important reactions to ensure that there is an adequate pool of citric acid cycle intermediates. Pyruvate carboxylase is activated by acetyl CoA, which accumulated when there is a lack of oxaloacetate."
"Pyruvate carboxylase is an important source of oxaloacetate for gluconeogenesis."
"T"
"Pyruvate carboxylase and phosphoenolpyruvate carboxykinase together provide a pathway for by-passing the irreversible reaction of pyruvate kinase, to permit gluconeogenesis from pyruvate (and hence from lactate)." 
71, pyrdh.bmp
"Pyruvate dehydrogenase is a thiamin (vitamin B1) dependent enzyme."
"T"
"This is why thiamin (vitamin B1) deficiency results in impaired carbohydrate metabolism."
"In thiamin (vitamin B1) deficiency pyruvate accumulates in muscle and there is acidosis."
"T"
"As a result of impaired pyruvate dehydrogenase activity there is a considerable increase in plasma concentrations of both pyruvate and lactate, leading to significant acidosis." 
72, glycol5.bmp
"The reaction of pyruvate kinase is readily reversible, so that phospho-enolpyruvate can be formed directly from pyruvate."
"F"
"Pyruvate kinase catalyses the essentially irreversible reaction from phospho-enolpyruvate to pyruvate, linked to phosphorylation of ADP to ATP."
"Pyruvate carboxylase is an important reaction in gluconeogenesis."
"T"
"The product of pyruvate carboxylase is oxaloacetate, which then undergoes further metabolism (catalysed by phospho-enolpyruvate carboxykinase, to yield phospho-enolpyruvate." 
73, pyrdh.bmp
"In thiamin (vitamin B1) deficiency pyruvate cannot be converted to acetyl CoA."
"T"
"Pyruvate dehydrogenase is a thiamin dependent enzyme."
"In thiamin (vitamin B1) deficiency pyruvate formed in muscle cannot be transaminated to alanine."
"F"
"Transaminases are vitamin B6 dependent; their activity is not affected by thiamin (vitamin B1) deficiency. There will be increased transamination to alanine as a result of the accumulation of pyruvate." 
74, pyrdh.bmp
"In thiamin (vitamin B1) deficiency pyruvate formed in muscle cannot be carboxylated to oxaloacetate."
"F"
"Pyruvate carboxylase, which catalyses this reaction, is not thiamin dependent."
"The reaction of pyruvate dehydrogenase leads to formation of ~3 ATP per mol of acetyl CoA formed."
"T"
"The reaction leads to the reduction of NAD to NADH, which leads to the formation of ~3 ATP when it is re-oxidized in the mitochondrial electron transport chain." 
75, G6Psource.bmp
"Glucose 6-phosphate is formed from glycogen by the action of the enzyme glycogen phosphorylase."
"F"
"The product of glycogen phosphorylase action is glucose 1-phosphate."
"Glucose 6-phosphate can be formed from glucose, but not from glycogen."
"F"
"The glucose 1-phosphate that is the product of glycogen phosphorylase action is readily isomerized to glucose 6-phosphate." 
76, G6Psource.bmp
"Glucose 6-phosphate cannot be converted to glucose 1-phosphate in liver."
"F"
"The isomerase that interconverts glucose 6-phosphate and glucose 1-phosphate is readily reversible, and this reaction does indeed occur in liver - it is an essential step in glycogen synthesis."
"Glucose 1-phosphate may be hydrolysed to yield free glucose in liver."
"F"
"There is no enzyme that will catalyse the hydrolysis of glucose 1-phosphate." 
77, G6Pdh.bmp
"In liver and red blood cells, glucose 6-phosphate may enter into either glycolysis or the pentose phosphate pathway."
"T"
"In tissues where the pentose phosphate pathway occurs, glucose 6-phosphate may enter either pathway."
"The pentose phosphate pathway provides an alternative to glycolysis."
"T"
"For every 3 mol of glucose 6-phosphate that enter the pentose phosphate pathway, there is a yield of 2 mol of fructose 6-phosphate and 1 of glyceraldehyde 3-phosphate - both of these are intermediates of glycolysis." 
78, G6Pdh.bmp
"A genetic defect of glucose 6-phosphatase leads to favism, a condition in which there is excessive haemolysis of red blood cells."
"F"
"The enzyme that is defective in favism is glucose 6-phosphate dehydrogenase, the first enzyme of the pentose phosphate pathway. Glucose 6-phosphatase acts to hydrolyse glucose 6-phosphate to yield free glucose."
"A genetic defect of glucose 6-phosphate dehydrogenase leads to favism, a condition in which there is excessive haemolysis of red blood cells."
"T"
"The enzyme that is defective in favism is glucose 6-phosphate dehydrogenase, the first enzyme of the pentose phosphate pathway." 
79, G6Pdh.bmp
"In favism (a genetic defect of glucose 6-phosphate dehydrogenase) red blood cells are more susceptible to oxidative stress because of a lack of NADPH for glutathione reductase."
"T"
"In red blood cells the only metabolic source of NADPH for glutathione reductase is the pentose phosphate pathway - in other tissues there are alternative pathways for NADPH formation."
"The pentose phosphate pathway is the main source of ribose for nucleic acid synthesis."
T"
"And it also provides a pathway for entry of pentoses into energy-yielding metabolism." 
80, G6Pdh.bmp
"The pentose phosphate pathway is especially important in tissues that are synthesizing fatty acids."
"T"
"The pentose phosphate pathway is normally responsible for about half the NADPH required for fatty acid synthesis, the remainder comes from the activity of the malic enzyme, part of the pathway by which acetyl CoA is made available for fatty acid synthesis in the cytosol."
 "The pentose phosphate pathway provides an alternative to glycolysis only in the fasting state."
"F"
"The pentose phosphate pathway can act in the fed or fasting state. Indeed, in liver and adipose tissue it is especially important in the fed state, as the source of about half of the NADPH required for fatty acid synthesis." 
81, GSHpx.bmp
 "The drugs and toxins that lead to a haemolytic crisis in favism (genetic defect of glucose 6-phosphate dehydrogenase) all require NADPH for their metabolism."
"F"
"The various compounds that precipitate a haemolytic crisis in favism all undergo redox cycling, producing oxygen radicals that lyse the red cell membrane - but this does not involve NADPH. The role of NADPH is in the activity of glutathione reductase, which is involved in the protection of cell membranes from oxidative damage and lysis."
"Glutathione is a tripeptide."
"T"
"Glutathione is gamma-glutamyl-cysteinyl-glycine, a tripeptide." 
82, G6Pdh.bmp
"People who lack glucose 6-phosphate dehydrogenase cannot synthesize fatty acids because of a lack of NADPH in liver and adipose tissue."
"F"
"Although the pentose phosphate pathway is normally responsible for about half the NADPH required for fatty acid synthesis, alternative pathways in liver and adipose tissue can produce enough NADPH for fatty acid synthesis."
"Overall in the pentose phosphate pathway 3 mol of glucose 6-phosphate leads to the formation of 6 mol of NADPH."
"T"
"And also the formation of 2 mol of fructose 6-phosphate, 1 mol of glyceraldehyde 3-phosphate and 3 mol of carbon dioxide."
83, G6Pdh.bmp
"The pentose phosphate pathway is the only source of NADPH for fatty acid synthesis."
"F"
"The pentose phosphate pathway is normally responsible for about half the NADPH required for fatty acid synthesis, the remainder comes from the activity of the malic enzyme, part of the pathway by which acetyl CoA is made available for fatty acid synthesis in the cytosol."
 "The drugs and toxins that lead to haemolytic crisis in favism (a genetic defect of glucose 6-phosphate dehydrogenase) all lead to the production of oxygen radicals."
"T"
"The various compounds that precipitate a haemolytic crisis in favism all undergo redox cycling, producing oxygen radicals that lyse the red cell membrane." 
84, G6Pdh.bmp
"Overall in the pentose phosphate pathway each mol of glucose 6-phosphate leads to the formation of 2 mol of NADPH."
"T"
"Both glucose 6-phosphate dehydrogenase and phosphogluconate dehydrogenase use NADP as the hydrogen acceptor."
"In favism (a genetic defect of glucose 6-phosphate dehydrogenase) red blood cells are more susceptible to oxidative stress because of a lack of NADPH for fatty acid synthesis."
"F"
"Red blood cells do not synthesize fatty acids. The role of NADPH that is relevant to haemolytic crisis in favism is in the activity of glutathione reductase, which is involved in the protection of cell membranes from oxidative damage and lysis." 
85, blank.bmp
 "The enzyme transketolase in the pentose phosphate pathway is thiamin (vitamin B1) dependent."
"T"
"Transketolase is indeed a thiamin-dependent enzyme. Measurement of transketolase activity in red blood cells, or better, measurement of its saturation with its coenzyme, provides a sensitive index of thiamin nutritional status."
"The nerve damage of thiamin (vitamin B1) deficiency is at least partially due to impairment of the activity of the pentose phosphate pathway."
"T"
"In both the time of development of nerve damage in thiamin deficiency and also the anatomical regions of the brain affected there is a good correlation between impairment of transketolase activity in the pentose phosphate pathway and the development of neurological damage." 
86, pyrdh.bmp
"The first step in the complete oxidation of pyruvate is a decarboxylation catalysed by pyruvate dehydrogenase."
"T"
"The pyruvate dehydrogenase multi-enzyme complex catalyses the decarboxylation of pyruvate, and oxidation of the 2-carbon fragment to acetate."
"The first step in complete oxidation of pyruvate is a decarboxylation catalysed by pyruvate carboxylase."
"F"
"Pyruvate carboxylase catalyses the carboxylation of pyruvate to oxaloacetate, not its decarboxylation. The enzyme involved in the (oxidative) decarboxylation of pyruvate is pyruvate dehydrogenase." 
87, pyrdh.bmp
 "The reaction of pyruvate dehydrogenase involves reduction of the disulphide bond of cystine at the active site of the enzyme."
"F"
"The disulphide that is reduced in the pyruvate dehydrogenase reaction is in the coenzyme lipoamide, not cystine."
"The reaction of pyruvate dehydrogenase involves decarboxylation and oxidation of pyruvate, then formation of acetyl CoA."
"T"
"Pyruvate dehydrogenase is a multi-enzyme complex, catalysing all of these steps sequentially." 
88, pyrdh.bmp
"The reaction of pyruvate dehydrogenase leads to the reduction of NAD+ to NADH, and hence the formation of ~3 x ATP per mol of pyruvate oxidized."
"T"
"People often forget these ~3 x ATP when they calculate the ATP yield of glucose oxidation, because they look at glycolysis (as far as pyruvate) then the citric acid cycle, and forget about pyruvate dehydrogenase."
"The reaction of pyruvate dehydrogenase is readily reversible, so that acetyl CoA can be used for the synthesis of pyruvate, and hence glucose."
"F"
"The reaction of the pyruvate dehydrogenase complex is irreversible - acetyl CoA cannot be used for pyruvate synthesis, and can never be a substrate for gluconeogenesis." 
89, blank.bmp
"Acetyl CoA is a substrate for gluconeogenesis."
"F"
"There is no pathway for the utilization of 2-carbon units such as the acetyl part of acetyl CoA for gluconeogenesis."
"Acetyl CoA arising from carbohydrate metabolism can be used in liver and adipose tissue for synthesis of fatty acids."
"T"
"Although there is dispute about the extent to which fatty acids are synthesized from carbohydrates, acetyl CoA arising from carbohydrate metabolism can indeed be used for fatty acid synthesis." 
90, TCAC8.bmp
"Oxaloacetate is an important precursor for gluconeogenesis."
"T"
"Any of the intermediates of the citric acid cycle (and hence all of those amino acids that lead to formation of citric acid cycle intermediates) can be used for formation of oxaloacetate, which is then used for gluconeogenesis."
"If oxaloacetate is withdrawn from the citric acid cycle for gluconeogenesis then it can be replaced by the action of pyruvate dehydrogenase."
"F"
"Pyruvate dehydrogenase catalyses the oxidative decarboxylation of pyruvate to acetyl CoA, which cannot be a substrate for nett synthesis of oxaloacetate. Oxaloacetate (a 4-carbon compound) is formed from pyruvate (a 3-carbon compound) by the action of pyruvate carboxylase." 
91, overview.bmp
"Ketone bodies are substrates for gluconeogenesis in the fasting state."
"F"
"Ketone bodies cannot ever be a substrate for gluconeogenesis."
"The rate of gluconeogenesis is increased by insulin."
"F"
"Gluconeogenesis is reduced in the presence of insulin, which is the hormone of the fed state. Gluconeogenesis is important in the fasting state." 
92, TCAC8.bmp
"If oxaloacetate is withdrawn from the citric acid cycle for gluconeogenesis then it can be replaced by the action of pyruvate carboxylase."
"T"
"Pyruvate carboxylase is specifically activated by acetyl CoA, which accumulates when there is a relative deficit of oxaloacetate."
"The carbon skeletons of most amino acids can be used for gluconeogenesis."
"T"
"Only two amino acids (leucine and lysine) give rise to only ketogenic fragments - all the others give rise to either a mixture of glucogenic and ketogenic fragments, or to glucogenic fragments only." 
93, glycsyn.bmp
 "Glycogen reserves in liver and muscle will meet energy requirements for several days in prolonged fasting."
"F"
"Glycogen reserves in liver and muscle will meet energy requirements for less than a day in fasting."
"The plasma concentration of glycogen increases in the fed state."
"F"
"Glycogen never occurs in plasma." 
94, glycsyn.bmp
"Liver synthesizes more glycogen when the hepatic portal blood concentration of glucose is high because of the activity of glucokinase in the liver."
"T"
"Hexokinase has a low Km, and is saturated, and hence acting at Vmax, well below the normal intracellular concentration of glucose in the liver. Glucokinase has a high Km, and only becomes significantly active when the concentration of glucose entering the liver is high, as in the fed state. This additional glucose is then used for synthesis of glycogen." 
"Glycogen is synthesized in the liver in the fed state, then exported to other tissues in low density lipoproteins."
"F"
"There is no transport of glycogen in the bloodstream." 
95, glycsyn.bmp
 "Glycogen is synthesized in the intestinal mucosa in the fed state, then exported to other tissues in chylomicrons."
"F"
"Glycogen is not synthesized in the intestinal mucosa, and there is no transport of glycogen in the bloodstream."
"Glycogen is synthesized in the liver in the fed state, then exported to other tissues in VLDL (very low density lipoproteins)."
"F"
"Glycogen is synthesized and stored in the liver; there is no transport of glycogen in the bloodstream." 
96, malasp.bmp
"Much of the NADH produced by glycolysis enters the mitochondria by the pathway shown here, the malate-aspartate shuttle."
"T"
"NADH cannot cross the mitochondrial membrane, so the reducing equivalents from glycolysis in the cytosol have to enter the mitochondria by a substrate shuttle; the malate-aspartate shuttle shown here is one such pathway."
"The malate-aspartate shuttle can only transport reducing equivalents from cytosolic glycolysis into the mitochondria when the intramitochondrial NAD+ : NADH ratio is low."
"F"
"A low NAD+ : NADH ratio (ie a higher than normal proportion as NADH inside the mitochondria) will inhibit the malate-aspartate shuttle, because the intramitochondrial malate dehydrogenase will tend to act in reverse." 
97, glycP.bmp
"Much of the NADH produced by glycolysis enters the mitochondria by the pathway shown here, the glycerophosphate shuttle."
"T"
"NADH cannot cross the mitochondrial membrane, so the reducing equivalents from glycolysis in the cytosol have to enter the mitochondria by a substrate shuttle; the glycerophosphate shuttle shown here is one such pathway."
"The glycerophosphate shuttle results in less ATP being formed than the malate-aspartate shuttle."
"T"
"In the malate-aspartate shuttle NAD+ inside the mitochondria is reduced to NADH, which yields ~3 ATP when it is oxidized in the electron transport chain. In the phosphoglycerate shuttle, although NADH is oxidized to NAD+ in the cytosol, it is FAD that is reduced inside the mitochondrion. Oxidation of FADH in the electron transport chain leads to the formation of ~2 ATP." 
98, blank.bmp
"In the fed state the main source of fatty acids for tissues is triacylglycerol in chylomicrons and very low-density lipoproteins (VLDL)."
"T"
"Chylomicrons come from the small intestine more or less immediately after a fat-rich meal; VLDL are assembled in, and secreted by, the liver an hour or so after a meal. Lipoprotein lipase at the cell surface hydrolyses triacylglycerol in these plasma lipoproteins, permitting uptake of free fatty acids into the cell."
"In the fasting state the main source of fatty acids for tissues is triacylglycerol in chylomicrons and very low-density lipoproteins (VLDL)."
"F"
"In the fasting state the main source of fatty acids for tissues will be non-esterified fatty acids released from adipose tissue. It is in the fed state that chylomicrons and VLDL are important. " 
99, blank.bmp
"In the fasting state the main source of fatty acids for tissues is non-esterified fatty acids bound to serum albumin."
"T"
"In the fasting state adipose tissue releases non-esterified fatty acids, which are transported in the bloodstream bound to serum albumin, as a major metabolic fuel for most tissues."
"In the fed state the main source of fatty acids for tissues is non-esterified fatty acids bound to serum albumin."
"F"
"Although there is always some release of non-esterified fatty acids into the bloodstream, they are mainly important in the fasting state. In the fed state the main source of fatty acids for tissues will be chylomicrons and VLDL (very low density lipoprotein). Chylomicrons come from the small intestine more or less immediately after a fat-rich meal; VLDL are assembled in, and secreted by, the liver an hour or so after a meal. Lipoprotein lipase at the cell surface hydrolyses triacylglycerol in these plasma lipoproteins, permitting uptake of free fatty acids into the cell." 
100, blank.bmp
"Non-esterified fatty acids are esterified to form acyl CoA in the cytosol immediately after entry into cells."
"T"
"Non-esterified fatty acids will lyse cell membranes by their detergent action (think about it - soap is a mixture of the sodium salts of fatty acids). Therefore they are always either protein bound (as to albumin in the bloodstream) or esterified to CoA or carnitine inside the cell."
"Free fatty acids are esterified to form acyl carnitine in the cytosol immediately after entry into cells."
"F"
"Fatty acids are esterified to CoA, forming acyl CoA, in the cytosol. It is only at the outer mitochondrial membrane that they are esterified to carnitine, for uptake into the mitochondrial matrix. Non-esterified fatty acids will lyse cell membranes by their detergent action (think about it - soap is a mixture of the sodium salts of fatty acids). Therefore they are always either protein bound (as to albumin in the bloodstream) or esterified to CoA or carnitine inside the cell."  
101, overview.bmp
"The beta-oxidation of fatty acids occurs in the cytosol."
"F"
"Beta-Oxidation of fatty acids occurs in the mitochondrial matrix."
"Fatty acid synthesis occurs in the mitochondrial matrix."
"F"
"Fatty acid synthesis occurs in the cytosol." 
102, blank.bmp
"Creatine is essential for transport of fatty acids into the mitochondrial matrix."
"F"
"It is carnitine that is essential for fatty acid transport into the mitochondrial matrix. Creatine is important as a reserve of phosphate for rephosphorylation of ADP to ATP in muscle."
"Creatinine is essential for transport of fatty acids into the mitochondrial matrix."
"F"
"It is carnitine that is essential for fatty acid transport into the mitochondrial matrix. Creatinine is a useless (non-enzymic) excretory product of creatine and creatine phosphate in muscle. Creatine is important as a reserve of phosphate for rephosphorylation of ADP to ATP in muscle."  
103, blank.bmp
"Acyl carnitine is formed from acyl CoA and carnitine at the outer face of the inner mitochondrial membrane."
"F"
"Acyl carnitine is formed from acyl CoA and carnitine at the outer face of the outer mitochondrial membrane."
"Acyl carnitine is formed from acyl CoA and carnitine at the inner face of the inner mitochondrial membrane."
"F"
"Acyl carnitine is formed from acyl CoA and carnitine at the outer face of the outer mitochondrial membrane. At the inner face of the inner mitochondrial membrane the acyl group is transferred from carnitine onto CoA."  
104, blank.bmp
 "Acyl CoA can only cross the inner mitochondrial membrane in exchange for free CoA leaving the mitochondrial matrix."
"F"
"Acyl CoA cannot cross the inner mitochondrial membrane at all."
"Acyl carnitine can only cross the inner mitochondrial membrane in exchange for free carnitine leaving the mitochondrial matrix."
"T"
"This antiporter, exchanging acyl carnitine for free carnitine, provides regulation of the uptake of fatty acids (esterified to carnitine) into the mitochondria for oxidation." 
105, blank.bmp
"The oxidation of fatty acids occurs in the mitochondrial matrix."
"T"
"Beta-oxidation is an intra-mitochondrial process, and hence is physically separated from fatty acid synthesis, which occurs in the cytosol."
 "The oxidation of fatty acids occurs in the cytosol."
"F"
"Beta-oxidation occurs in the mitochondrial matrix, and hence is physically separated from fatty acid synthesis, which occurs in the cytosol." 
106, betaox1.bmp
"There is a yield of ~5 ATP from this reaction sequence."
"T"
"A flavin is reduced in reaction A, which results in the formation of ~2 ATP when re-oxidized in the mitochondrial electron transport chain. NAD is reduced in reaction C, which results in the formation of ~3 ATP when re-oxidized in the mitochondrial electron transport chain."
"There is a cost of ~5 ATP for this reaction sequence."
"F"
"This is an energy-yielding pathway in which coenzymes are reduced, and undergo re-oxidation in the mitochondrial electron transport chain. A flavin is reduced in reaction A, which results in the formation of ~2 ATP when re-oxidized. NAD is reduced in reaction C, which results in the formation of ~3 ATP when re-oxidized." 
107, betaox1.bmp
"The fatty acyl CoA substrate undergoes reduction in reaction A."
"F"
"The fatty acyl CoA is oxidized in this reaction - 2 H are removed (and transferred to the flavin coenzyme, which is thus reduced), resulting in the formation of a carbon-carbon double bond."
"The fatty acyl CoA substrate undergoes oxidation in reaction A."
"T"
"The fatty acyl CoA is oxidized in this reaction - 2 H are removed (and transferred to the flavin coenzyme, which is thus reduced), resulting in the formation of a carbon-carbon double bond." 
108, betaox1.bmp
"The substrate undergoes hydrolysis in reaction B."
"F"
"This is a hydration - the addition of water across a double bond, resulting in formation of a hydroxyl group. Hydrolysis is the cleavage of a bond by water."
"The substrate undergoes dehydration in reaction B."
"F"
"This is a hydration - the addition of water across a double bond, resulting in formation of a hydroxyl group. Dehydration would be the reverse reaction, the removal of water." 
109, betaox1.bmp
"The hydroxyacyl CoA substrate undergoes oxidation in reaction C."
"T"
"Two hydrogens are removed from the alcohol group of the substrate to yield an oxo-group. This is indeed an oxidation. The hydrogens are transferred to NAD+, which is therefore reduced in this reaction."
"The hydroxyacyl CoA substrate undergoes reduction in reaction C."
"F"
"Two hydrogens are removed from the alcohol group of the substrate to yield an oxo-group. This is indeed an oxidation. The hydrogens are transferred to NAD+, which is therefore reduced in this reaction." 
110, betaox2.bmp
"The acetyl CoA released in this reaction may undergo complete oxidation in the citric acid cycle."
"T"
"Complete oxidation in the citric acid cycle will be the fate of the acetyl CoA produced by the beta-oxidation of fatty acids in most tissues."
"The acetyl CoA released in this reaction may be used for the synthesis of ketone bodies in the liver."
"T"
 "The liver has a greater capacity for beta-oxidation of fatty acids than it requires to meet its own energy needs, and in the fasting state much of the acetyl CoA produced by beta-oxidation is indeed used for synthesis of ketone bodies, which are exported for use by muscle and other tissues." 
111, betaox2.bmp
"The fatty acyl CoA released in this reaction may undergo chain elongation."
"F"
"This is part of the reaction of beta-oxidation of fatty acids. The fatty acyl CoA released in this reaction will undergo a further cycle of beta-oxidation."
"The fatty acyl CoA released in this reaction may undergo chain elongation."
"F"
"This is part of the reaction of beta-oxidation of fatty acids. The fatty acyl CoA released in this reaction will undergo a further cycle of beta-oxidation." 
112, betaox1.bmp
"The sequence of reactions A - C shown here is chemically the same as in part of the citric acid cycle."
"T"
"In the citric acid cycle the conversion of succinate to oxaloacetate is indeed chemically the same as this sequence of reactions in the beta-oxidation of fatty acids."
"The sequence of reactions A - C shown here is chemically the reverse of part of the citric acid cycle."
"F"
"In the citric acid cycle the conversion of succinate to oxaloacetate is chemically the same as this sequence of reactions in the beta-oxidation of fatty acids. It is in fatty acid synthesis that the reverse sequence of chemical reactions occurs." 
113, blank.bmp
"Fatty acid synthesis occurs in the cytosol."
"T"
"Fatty acid synthesis is a cytosolic reaction, and is thus physically separated from the beta-oxidation of fatty acids, which occurs in the mitochondrial matrix."
"Fatty acid synthesis occurs in the mitochondrial matrix."
"F"
"Fatty acid synthesis is a cytosolic reaction, and is thus physically separated from the beta-oxidation of fatty acids, which occurs in the mitochondrial matrix." 
114. fasyn1.bmp
"Malonyl CoA is formed by the decarboxylation of acetyl CoA
"F"
"The reaction to form malonyl CoA from acetyl CoA is a carboxylation reaction, not a decarboxylation - carbon dioxide is added to the substrate."
"The enzyme that catalyses the formation of malonyl CoA is biotin-dependent."
"T"
"This is a carboxylation reaction, and biotin is the coenzyme for most carboxylation reactions - carboxy-biotin, bound at the catalytic site of the enzyme, is formed as an intermediate in the reaction." 
115, fasyn2.bmp
"Compound B formed in this reaction sequence may undergo a further cycle of beta-oxidation."
"F"
"This is the reaction sequence of fatty acid synthesis; compound B will undergo a further cycle of reactions C - D, resulting in chain elongation."
"Compound B formed in this reaction sequence may undergo a further cycle of chain elongation."
"T"
"This is the reaction sequence of fatty acid synthesis; compound B will indeed undergo a further cycle of reactions C - D, resulting in chain elongation until palmitate (C16:0) is formed and released from the multi-enzyme complex." 
116, fasyn2.bmp
"In reaction C the keto-acyl ACP substrate undergoes oxidation."
"F"
"The keto-acyl ACP is reduced in this reaction. Two hydrogens are transferred from NADPH to reduce the keto group to an alcohol."
"In reaction C the keto-acyl ACP substrate undergoes reduction."
"T"
"The keto-acyl ACP is indeed reduced in this reaction. Two hydrogens are transferred from NADPH to reduce the keto group to an alcohol." 
117, fasyn2.bmp
"In reaction E the enoyl ACP substrate undergoes oxidation."
"F"
"The substrate is reduced in this reaction. Two hydrogens are transferred from NADPH to saturate the carbon-carbon double bond."
"In reaction E the enoyl ACP substrate undergoes oxidation."
"T"
"The substrate is indeed reduced in this reaction. Two hydrogens are transferred from NADPH to saturate the carbon-carbon double bond." 
118, fasyn2.bmp
"Reaction D is a condensation."
"F"
"This reaction is a dehydration - removal of water from an alcohol to yield a carbon-carbon double bond. In a condensation reaction water is eliminated in the formation of a bond between two separated substrates."
"Reaction D is a hydrolysis"
"F"
"This reaction is a dehydration - removal of water from an alcohol to yield a carbon-carbon double bond. In hydrolysis water is added across a bond to cleave it." 
119, fasyn2.bmp
"Reaction E does not occur in the synthesis of unsaturated fatty acids."
"F"
"Fatty acid synthesis must always follow the complete sequence of reactions shown here, and the product is always a saturated fatty acid. Unsaturated fatty acids are synthesized by desaturation of saturated fatty acids, not by the reaction sequence shown here."
"Reaction E does not occur in the synthesis of unsaturated fatty acids."
"F"
"Fatty acid synthesis must always follow the complete sequence of reactions shown here, and the product is always a saturated fatty acid. Unsaturated fatty acids are synthesized by desaturation of saturated fatty acids, not by the reaction sequence shown here." 
120, fasyn2.bmp
"There is a yield of ~6 ATP from the reaction sequence shown here."
"F"
"There is no yield of ATP from this reaction sequence. NADPH is required for both reduction reactions; indeed, since the NADPH would otherwise have (indirectly) undergone oxidation in the mitochondrial electron transport chain there is an effective cost of ~6 ATP in this reaction sequence."
"There is a cost of ~6 ATP from the reaction sequence shown here."
"T"
"NADPH is required for both reduction reactions; since it would otherwise have (indirectly) undergone oxidation in the mitochondrial electron transport chain there is indeed an effective cost of ~6 ATP in this reaction sequence." 
121, overview.bmp
"There is an increase in the rate of beta-oxidation in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"T"
"As the supply of non-esterified fatty acids increases in the fasting state, so the liver oxidizes more fatty acids, sparing glucose for use by other tissues that are more or less completely dependent on a supply of glucose."
"There is a decrease in the rate of beta-oxidation in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"F"
"As the supply of non-esterified fatty acids increases in the fasting state, so the liver oxidizes more fatty acids, sparing glucose for use by other tissues that are more or less completely dependent on a supply of glucose." 
122, overview.bmp
"There is an increase in the rate of ketogenesis in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"T"
"As the supply of non-esterified fatty acids increases in the fasting state, so the liver oxidizes more fatty acids, sparing glucose for use by other tissues that are more or less completely dependent on a supply of glucose. Liver can oxidize more fatty acids than it requires to meet its own energy needs, and synthesizes ketone bodies for export to other tissues."
"There is a decrease in the rate of ketogenesis in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"F"
"As the supply of non-esterified fatty acids increases in the fasting state, so the liver oxidizes more fatty acids, sparing glucose for use by other tissues that are more or less completely dependent on a supply of glucose. Liver can oxidize more fatty acids than it requires to meet its own energy needs, and synthesizes ketone bodies for export to other tissues." 
123, overview.bmp
"There is an increase in the rate of ketone body oxidation in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"F"
"The liver does not oxidize ketone bodies - it synthesizes them for export to other tissues."
"There is an increase in the rate of ketogenesis in muscle when there is an increase in the plasma concentration of non-esterified fatty acids."
"F"
"Muscle does not synthesize ketone bodies - it oxidizes them." 
125, overview.bmp
"There is an increase in the rate of lipogenesis in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"F"
"When non-esterified fatty acids in plasma increase in the fasting state, there is a reduction in the rate of lipogenesis (new synthesis of fatty acids) and the liver increases the rate of beta-oxidation of fatty acids."
"There is a decrease in the rate of lipogenesis in the liver when there is an increase in the plasma concentration of non-esterified fatty acids."
"T"
"When non-esterified fatty acids in plasma increase in the fasting state, there is a reduction in the rate of lipogenesis (new synthesis of fatty acids) and the liver increases the rate of beta-oxidation of fatty acids." 
126, ketone1.bmp
"Compound D is an important metabolic fuel in the fasting state."
"F"
"Compound D is acetone. It is formed by non-enzymic decarboxylation of acetoacetate (compound B), but there is only a limited capacity to metabolize it. Reaction E therefore represents a significant loss of metabolic fuel in the fasting state."
"Reaction E is important in providing metabolic fuel to muscle in the fasting state."
"F"
"Reaction E is the non-enzymic decarboxylation of acetoacetate to acetone. There is only a limited capacity to metabolize acetone, so this reaction represents a significant loss of metabolic fuel in the fasting state." 
127, ketone1.bmp
"Reaction F can be considered to be a way in which liver can export ~3 ATP to muscle in the fasting state."
"T"
"Reaction F is the reduction of acetoacetate to hydroxybutyrate, at the cost of NADH. In muscle hydroxybutyrate is re-oxidized to acetoacetate, yielding NADH, which yields ~3 ATP when it is oxidized in the mitochondrial electron transport chain."
"Reaction F is important to preserve metabolic fuel in the fasting state."
"T"
"Reaction E is the non-enzymic decarboxylation of acetoacetate to acetone. There is only a limited capacity to metabolize acetone, so this reaction represents a significant loss of metabolic fuel in the fasting state. Reduction of acetoacetate to hydroxybutyrate, which is stable, and does not undergo non-enzymic loss, therefore prevents this loss of metabolic fuel." 
128, ketone1.bmp
"Compounds B, C and D are all ketones."
"F"
"Acetoacetate (compound B) and acetone (compound D) are chemically ketones, but hydroxybutyrate (compound C) is not. Collectively these three compounds are known as 'ketone bodies', even though hydroxybutyrate is not a ketone, because of their metabolic relationship. People sometimes talk loosely about 'ketones' when they really mean these three compounds."
"Compound D provides an important metabolic signal in the fasting state."
"F"
"Although acetone is clinically useful to detect ketosis (an elevated blood concentration of ketone bodies), it is only metabolized to a limited extent, and has no known signalling function." 
129, ketone1.bmp
"Acetone is formed from hydroxybutyrate in a non-enzymic reaction."
"F"
"Acetone (compound D) is formed from acetoacetate (compound B) in a non-enzymic reaction - the formation of hydroxybutyrate (compound C) protects valuable metabolic fuel against waste due to the formation of acetone, which is only poorly metabolized."
 "Ketone bodies are an important substrate for gluconeogenesis in the fasting state."
"F"
"Ketone bodies yield acetyl CoA, and can never be a substrate for gluconeogenesis." 
130, ketone2.bmp
"Reaction D can be considered to be an alternative to part of the citric acid cycle."
"T"
"In the citric acid cycle succinyl CoA is converted to succinate in a reaction linked to the phosphorylation of either GDP to GTP or (in tissues that do not carry out gluconeogenesis) ADP to ATP. In this reaction succinyl CoA transfers its CoA directly onto acetoacetate, thus by-passing the reaction in the citric acid cycle that yields GTP or ATP."
"Compound B may be a substrate for gluconeogenesis in the liver in the fasting state."
"F"
"Compound B is acetyl CoA, which can never be a substrate for gluconeogenesis." 
 131, blank.bmp
"Low density lipoprotein (LDL) contains a higher proportion of cholesterol relative to other lipids than other lipoproteins."
"T"
"LDL is formed from very low density lipoprotein (VLDL) by removal of triacylglycerol in peripheral tissues. As the triacylglycerol is removed, so the proportion of cholesterol in the lipoprotein increases."
"Low density lipoprotein (LDL) is synthesized in the liver and can be converted to very low density lipoprotein (VLDL) in the circulation."
"F"
"VLDL is synthesized in the liver, and exported to provide a source of triacylglycerol and cholesterol to other tissues. As tissues remove triacylglycerol (and some cholesterol) from VLDL, so it becomes intermediate density lipoprotein (IDL) and then LDL." 
132, blank.bmp
"Tissues cannot take up fatty acids and cholesterol from chylomicrons until they have acquired two apo-proteins from high density lipoprotein (HDL) in the circulation."
"T"
"Chylomicrons are assembled in the intestinal mucosa. In the circulation they acquire three proteins from HDL. Two of these activate cell surface lipoprotein lipase and lecithin cholesterol acyltransferase, which permit tissues to take up fatty acids from chylomicron triacylglycerol and cholesterol from chylomicron cholesteryl esters."
"Chylomicron remnants are only cleared by the liver because the chylomicrons acquire apoprotein E from high density lipoprotein (HDL) in the circulation."
"T"
"Chylomicrons are assembled in the intestinal mucosa. In the circulation they acquire three proteins from HDL. One of these is apo-protein E, which binds to the liver receptors for receptor-mediated uptake of lipid-depleted chylomicron remnants." 
133, blank.bmp
"Very low density lipoprotein (VLDL) contains both newly synthesized triacylglycerol and triacylglycerol from chylomicron remnants."
"T"
"VLDL are assembled and exported by the liver, containing both newly synthesized triacylglycerol, cholesterol and phospholipids, and also lipids salvaged from chylomicron remnants that are cleared by the liver."
"Very low density lipoproteins (VLDL) transfer some of their proteins to high density lipoprotein (HDL) in the circulation."
"T"
"As VLDL become lipid depleted in the circulation, so they transfer apoproteins C-I and C-II to HDL, becoming intermediate density lipoprotein (IDL) in the process." 
134, blank.bmp
"Intermediate density lipoproteins (IDL) take up cholesteryl esters from high density lipoprotein (HDL) in the circulation."
"T"
"As the IDL takes up cholesteryl esters from HDL, so it becomes low density lipoprotein (LDL), which is cleared by the liver. In this way cholesterol that has been removed from tissues by HDL is returned to the liver."
"High density lipoprotein (HDL) takes up cholesterol from peripheral tissues for return to the liver."
"T"
"In the circulation HDL transfers cholesteryl esters to intermediate density lipoprotein (IDL), which becomes low density lipoprotein (LDL) in the process. LDL is then cleared by the liver." 
135, blank.bmp
"Low density lipoprotein (LDL) is cleared from the circulation by lipoprotein lipase (sometimes known as clearing factor lipase)."
"F"
"LDL is cleared from the circulation by receptor-mediated uptake into the liver. Lipoprotein lipase is an extracellular enzyme of peripheral tissues that acts to take up fatty acids from triacylglycerol in chylomicrons and very low density lipoprotein (VLDL)."
"Tissues take up fatty acids from chylomicrons and very low density lipoprotein due to the action of extracellular lipoprotein lipase."
"T"
"This lipase is sometimes known as 'clearing factor lipase'. After a moderately fat-rich meal plasma is milky because of the presence of chylomicrons; as lipid is removed from the chylomicrons by lipoprotein lipase they shrink in size and no longer scatter light, so the plasma clears." 
136, blank.bmp
"Hepatic uptake of low density lipoprotein (LDL) is controlled by the liver content of cholesterol."
"T"
"The synthesis of LDL receptors in the liver is regulated by the liver content of cholesterol."
"Genetic variants of apoprotein E in low density lipoprotein (LDL) affect hepatic uptake of LDL.
"T"
"Some genetic variants of apoprotein E have a poor affinity for the hepatic LDL receptor; this provides a basis for some of the genetic susceptibility to atherosclerosis." 
137, blank.bmp
"Chemical modification (especially oxidation) of apoprotein E in low density lipoprotein (LDL) enhances its uptake by the hepatic LDL receptor."
"F"
"Chemical modification of apoprotein E in LDL, commonly secondary to oxidative damage to the lipids in LDL, reduces its affinity for the hepatic LDL receptor, and so reduces the uptake of LDL into the liver."
"Chemical modification (especially oxidation) of apoprotein E in low density lipoprotein (LDL) impairs its uptake by the hepatic LDL receptor."
"T"
"Chemical modification of apoprotein E in LDL, commonly secondary to oxidative damage to the lipids in LDL, reduces its affinity for the hepatic LDL receptor, and so reduces the uptake of LDL into the liver." 
138, blank.bmp
"Macrophages take up low density lipoprotein (LDL) in an uncontrolled fashion."
"T"
"Unlike the hepatic uptake of LDL, which is regulated, the macrophage scavenger receptor takes up LDL (and oxidized LDL) in an uncontrolled manner. As the macrophages become lipid engorged ('foam cells') they infiltrate the blood vessel endothelium, forming fatty streaks that eventually develop into atherosclerotic plaque."
"The uptake of low density lipoprotein (LDL) into macrophages is regulated by the cholesterol content of the cells."
"F"
"Unlike the hepatic uptake of LDL, which is regulated, the macrophage scavenger receptor takes up LDL (and oxidized LDL) in an uncontrolled manner. As the macrophages become lipid engorged ('foam cells') they infiltrate the blood vessel endothelium, forming fatty streaks that eventually develop into atherosclerotic plaque." 
139, blank.bmp
"The function of high density lipoprotein (HDL) is to carry triacylglycerol from the liver to adipose tissue."
"F"
"This is the function of VLDL; HDL carries cholesterol from tissues back to the liver by way of transferring cholesteryl esters into low density lipoprotein (LDL), which is cleared by the liver."
 "A high concentration of low density lipoprotein (LDL) cholesterol in plasma is a risk factor for atherosclerosis."
"T"
"The uptake of LDL by the liver is regulated, and oxidized LDL is poorly taken up. LDL that is not cleared by the liver is taken up by the unregulated macrophage scavenger receptor. As the macrophages become lipid engorged ('foam cells') they infiltrate the blood vessel endothelium, forming fatty streaks that eventually develop into atherosclerotic plaque."  
140, TCAC.bmp
"This pathway permits complete oxidation of the acetate part of acetyl CoA to carbon dioxide and water."
"T"
"This is the citric acid cycle."
"There is a nett yield of ~12 ATP for each acetyl CoA oxidized in this pathway."
"T"
"For each turn of the cycle: 3 x NADH are formed - these yield ~3 ATP when oxidized in the mitochondrial electron transport chain; 1 x FADH is formed - this yields ~2 ATP when oxidized in the mitochondrial electron transport chain; 1 x GTP (or in some tissues ATP) is formed by substrate-level phosphorylation." 
141, TCAC.bmp
"This pathway can be used to provide oxaloacetate for gluconeogenesis, by interconversion of the carbon skeletons of amino acids."
"T"
"Oxaloacetate is the major substrate for gluconeogenesis, and as long as it is being replenished by adding in 4- and 5-carbon intermediates of the cycle (eg from carbon skeletons of amino acids), it can be withdrawn for gluconeogenesis."
"This pathway can be used to form the carbon skeletons of non-essential amino acids."
"T"
"As long as oxaloacetate is replenished by adding in 4- or 5-carbon intermediates of the cycle, other intermediates can indeed be withdrawn for synthesis of amino acids and other compounds." 
142, TCAC.bmp
"Because oxaloacetate is regenerated in each turn of the cycle, this pathway provides a way in which the acetate part of acetyl CoA can be a substrate for gluconeogenesis."
"F"
"Acetyl CoA can never be a substrate for gluconeogenesis. Two carbon atoms enter the cycle from acetyl CoA, forming citrate, but two carbon atoms are lost in each turn of the cycle. This means that adding acetate from acetyl CoA does not increase the total amount of oxaloacetate in the cell, and therefore it cannot be withdrawn for gluconeogenesis."
"When oxaloacetate is withdrawn from this cycle for gluconeogenesis in the liver in the fasting state the rate of oxidation of acetyl CoA slows down."
"T"
"If oxaloacetate is depleted (eg by increased gluconeogenesis in the liver in the fasting state) the rate of citric acid cycle activity decreases. Under these conditions acetyl CoA from beta-oxidation of fatty acids is used for synthesis of ketone bodies, which are exported from the liver for use by other tissues." 
143, TCAC.bmp
"The sequence of reactions between succinate and oxaloacetate is chemically the same as that in beta-oxidation of fatty acids."
"T"
"Succinate is oxidized to fumarate by removal of 2 hydrogens onto a flavin; water is then added across the carbon-carbon double bond of fumarate to form malate, then the -CHOH group of malate is oxidized to the oxo-group of oxaloacetate. Chemically this is exactly the same sequence of reactions as occurs in beta-oxidation of fatty acids." 
"Although 2 carbon atoms are added from acetyl CoA, and two are lost in each turn of the cycle, label from radioactive acetate becomes incorporated into oxaloacetate."
"T"
"The two carbon atoms that are lost in the cycle are not the same two atoms as are added from acteyl CoA." 
144, TCAC1.bmp
"Because citrate is a symmetrical compound, the two carbon atoms that are added from acetyl CoA could be either carbons 1 and 2 or carbons 5 and 6 of isocitrate."
"F"
"Although citrate is indeed a symmetrical compound, it behaves asymmetrically in the cycle. This is because it does not leave citrate synthase to go into free solution, but is passed directly from the active site of citrate synthase onto that of aconitase."
"When isocitrate dehydrogenase activity is reduced, or when the enzyme is saturated, additional citrate formed by citrate synthase leaves the enzyme and is available for transport into the cytosol to provide acetyl CoA for fatty acid synthesis."
"T"
"When the rate of citric acid cycle activity is adequate to meet energy needs, isocitrate dehydrogenase activity is reduced. This means that citrate cannot be passed from the active site of citrate synthase directly to aconitase, since its active site is already occupied. Therefore citrate now leaves the enzyme and can leave the mitochondrion to provide acetyl CoA in the cytosol for fatty acid synthesis." 
145, TCAC2.bmp
"The reaction of isocitrate dehydrogenase is a reduction of the substrate."
"F"
"Isocitrate is oxidized in this reaction, at the expense of NAD+, which is reduced."
"This reaction provides ~2 ATP."
"F"
"This reaction produces NADH; when NADH is oxidized in the electron transport chain there is a yield of ~3 ATP." 
146, TCAC2.bmp
"This reaction is a carboxylation."
"F"
"This reaction involves removal of carbon dioxide from the substrate. Therefore it is a decarboxylation."
"Biotin is the coenzyme for this reaction."
"F"
"Biotin is the coenzyme for carboxylation reactions. This reaction is a decarboxylation, involving removal of carbon dioxide from the substrate." 
147, TCAC3.bmp
"This reaction is catalysed by a thiamin-dependent multi-enzyme complex, like that of pyruvate dehydrogenase."
"T"
"The ketoglutarate dehydrogenase multi-enzyme complex is closely similar to the pyruvate dehydrogenase multi-enzyme complex, and is indeed thiamin dependent."
"Because this reaction is thiamin (vitamin B1) dependent, the activity of the citric acid cycle is severely impaired in thiamin deficiency."
"F"
"Although the activity of ketoglutarate dehydrogenase is indeed impaired in thiamin deficiency, the citric acid cycle continues more or less as normal. There is an alternative, thiamin-independent, pathway for conversion of ketoglutarate to succinate, by way of transamination to glutamate and decarboxylation to gamma-aminobutyrate (GABA)." 
148, TCAC3.bmp
"This reaction is oxidation of the substrate."
"T"
"Ketoglutarate is indeed oxidized in this reaction, with reduction of NAD+ to NADH."
"This reaction provides ~3 ATP."
"T"
"This reaction produces NADH; when NADH is oxidized in the electron transport chain there is a yield of ~3 ATP." 
149, TCAC4.bmp
"This reaction is a substrate-level phosphorylation."
"T"
"Substrate-level phosphorylation occurs when phosphate is transferred onto ADP or GDP other than via the mitochondrial electron transport chain (or by transfer from ATP)." 
"When ketone bodies are being metabolized in muscle this reaction is replaced by a reaction in which CoA is transferred from succinyl CoA onto acetoacetate."
"T"
"Transfer of CoA from succinyl CA onto acetoacetate permits control over the entry of ketone bodies into the citric acid cycle. If there is not enough succinyl CoA available, this means that there will not be enough oxaloacetate available for citrate synthesis. Therefore there is no need to take up acetoacetate for oxidation in the citric acid cycle." 
150, TCAC4.bmp
"In tissues that do not carry out gluconeogenesis there is a different form of this enzyme that uses ADP rather than GDP as the phosphate acceptor."
"T"
"The importance of the GTP formed in this reaction is that it is used in the reaction of phosphoenolpyruvate carboxykinase, the enzyme that withdraws oxaloacetate from the citric acid cycle for gluconeogenesis. If too much oxaloacetate were being withdrawn, so that citric acid cycle activity was impaired, then there would be less GTP formed. This reaction thus provides a link between citric acid cycle activity and the ability to withdraw oxaloacetate for gluconeogenesis."
"This reaction provides a link between citric acid cycle activity and the ability to withdraw oxaloacetate for gluconeogenesis."
"T"
"The importance of the GTP formed in this reaction is that it is used in the reaction of phosphoenolpyruvate carboxykinase, the enzyme that withdraws oxaloacetate from the citric acid cycle for gluconeogenesis. If too much oxaloacetate were being withdrawn, so that citric acid cycle activity was impaired, then there would be less GTP formed. In tissues that do not carry out gluconeogenesis there is a different form of this enzyme that uses ADP rather than GDP as the phosphate acceptor." 
151 TCAC5.bmp
"This reaction is a reduction of the substrate."
"F"
"Succinate is oxidized to fumarate by the removal of two hydrogens onto FAD."
"This reaction yields ~3 ATP."
"F"
"This reaction reduces enzyme-bound FAD, which in turn reacts directly with ubiquinone in the mitochondrial electron transport chain. Oxidation of reduced ubiquinone results in the formation of ~2 ATP." 
152, TCAC6.bmp
"This reaction is a hydrolysis."
"F"
"This reaction is a hydration - the addition of water across a carbon-carbon double bond to form an alcohol group. Hydrolysis is the cleavage of a bond by water."
"This reaction is a condensation."
"F"
"This reaction is a hydration - the addition of water across a carbon-carbon double bond to form an alcohol group. Condensation is the formation of a bond between two substrates by elimination of water." 
153, TCAC7.bmp
"This reaction is the oxidation of malate."
"T"
"Malate is oxidized to oxaloacetate in this reaction, with the reduction of NAD+ to NADH."
"This reaction yields ~3 ATP."
"T"
"This reaction produces NADH; when NADH is oxidized in the electron transport chain there is a yield of ~3 ATP." 
154, TCAC8.bmp
"The reaction of pyruvate carboxylase is essential for gluconeogenesis from lactate in the liver."
"T"
"Lactate is oxidized to pyruvate, which must then be carboxylated to oxaloacetate for gluconeogenesis."
"Pyruvate carboxylase is a biotin-dependent enzyme."
"T"
"Like most other carboxylases, pyruvate carboxylase uses enzyme-bound biotin, which is carboxylated in the first stage of the reaction." 
155, TCAC8.bmp
"The reaction of pyruvate carboxylase is important to replenish the pool of citric acid cycle intermediates."
"T"
"If intermediates are being withdrawn from the citric acid cycle (eg to synthesize amino acids) then some other means of providing a source of oxaloacetate is essential in order to maintain citric acid cycle activity. Pyruvate carboxylase is one of the most important of such anaplerotic reactions."
"The reaction of phosphoenolpyruvate carboxykinase is important to replenish the pool of citric acid cycle intermediates."
"F"
"Phosphoenolpyruvate carboxykinase catalyses the removal of oxaloacetate from the cycle, for gluconeogenesis. It is pyruvate carboxylase that is important to replenish the pool of citric acid cycle intermediates." 
156, TCAC8.bmp
"The use of GTP as the phosphate donor in the phosphoenolpyruvate carboxykinase reaction provides a link between citric acid cycle activity and gluconeogenesis."
"T"
"The main source of GTP in the mitochondria is the substrate-level phosphorylation of GDP catalysed by succinyl CoA synthetase. If too much oxaloacetate were being withdrawn, so that citric acid cycle activity was impaired, then there would be less GTP formed, so there would be lower activity of phosphoenolpyruvate carboxykinase, and hence less withdrawal of oxaloacetate."
"The use of pyruvate carboxylase and phosphoenolpyruvate carboxykinase to reverse the reaction catalysed by pyruvate kinase explains much of the phenomenon of oxygen debt after vigorous exercise."
"T"
"After vigorous exercise the lactate that has been formed by exercising muscle must be converted back to glucose. This requires pyruvate carboxylase and phosphoenolpyruvate carboxykinase, and the cost of ATP and GTP for these two reactions explains part of the increased oxidation of substrates to provide ATP that is seen as increased metabolic rate and hence increased oxygen consumption." 
-999
Copyright David A Bender 2002
