1, ATPase.bmp
"In ATP-requiring enzyme reactions, either the substrate or the enzyme may be phosphorylated during the course of the reaction."
"T"
"Overall, when ATP is involved in an endothermic (endergonic) enzyme-catalysed reaction, what is observed is hydrolysis of ATP to ADP and phosphate. However, although this is the overall reaction of ATP, it proceeds in two separate stages. Commonly, either the enzyme or the substrate is phosphorylated as the first stage of the reaction, with the release of ADP, then in a later stage of the reaction the phosphate is released. In some reactions the substrate may be adenylated, with release of pyrophosphate, in the first stage of the reaction."
"In ATP-requiring enzyme reactions, the hydrolysis of ATP to ADP and phosphate is independent of the reaction being catalysed"
"F"
"Overall, when ATP is involved in an endothermic (endergonic) enzyme-catalysed reaction, what is observed is hydrolysis of ATP to ADP and phosphate. However, although this is the overall reaction of ATP, it proceeds in two separate stages. Commonly, either the enzyme or the substrate is phosphorylated as the first stage of the reaction, with the release of ADP, then in a later stage of the reaction the phosphate is released. In some reactions the substrate may be adenylated, with release of pyrophosphate, in the first stage of the reaction."
2, ATPase.bmp
"Endothermic (endergonic reactions) are commonly linked to the hydrolysis of ATP."
"T"
"Overall, when ATP is involved in an endothermic (endergonic) enzyme-catalysed reaction, what is observed is hydrolysis of ATP to ADP and phosphate. However, although this is the overall reaction of ATP, it proceeds in two separate stages. Commonly, either the enzyme or the substrate is phosphorylated as the first stage of the reaction, with the release of ADP, then in a later stage of the reaction the phosphate is released. In some reactions the substrate may be adenylated, with release of pyrophosphate, in the first stage of the reaction."
"Exothermic (exergonic reactions) are commonly linked to the hydrolysis of ATP."
"F"
"It is endothermic reactions that are linked to the hydrolysis of ATP; by contrast, a number exothermic reactions are linked to the phosphorylation of ADP to ATP."
3, ATPase.bmp
"ATPase catalyses the hydrolysis of ATP to ADP and phosphate."
"T"
"By definition, ATPase is an enzyme that catalyses the hydrolysis of ATP to ADP and phosphate - an exothermic reaction. The reaction is reversible, although phosphorylation of ADP to ATP is an endothermic reaction."
"ATPase catalyses the phosphorylation of ADP to ATP."
"T"
"The condensation of ADP + phosphate to form ATP is the reverse of the hydrolysis of ATP to ADP + phosphate; the reaction of ATPase is indeed reversible, although phosphorylation of ADP to ATP is an endothermic reaction."
4, ATPase.bmp
"Exothermic (exergonic) reactions are commonly linked to the hydrolysis of ATP."
"F"
"The hydrolysis of ATP is itself an exothermic reaction. It is endothermic reactions that are commonly linked to the hydrolysis of ATP to ADP and phosphate."
"Endothermic (endergonic) reactions are commonly linked to the hydrolysis of ATP."
"T"
"The hydrolysis of ATP is an exothermic reaction and is commonly linked to endothermic reactions."
5, ATPase.bmp
"Endothermic (exergonic) reactions are commonly linked to the phosphorylation of ADP."
"F"
"The phosphorylation of ADP to ATP is itself an endothermic reaction, and is commonly linked (indirectly) to a variety of exothermic reactions."
"Exothermic (endergonic reactions) are commonly linked to the phosphorylation of ADP."
"T"
"The phosphorylation of ADP to ATP is an endothermic reaction, and is commonly linked (indirectly) to a variety of exothermic reactions."
6, ATPase.bmp
"Anabolic (biosynthetic reactions) are commonly linked to hydrolysis of ATP."
"T"
"Many anabolic reactions are endothermic and are linked to the (overall) hydrolysis of ATP to ADP + phosphate."
"Anabolic (biosynthetic reactions) are commonly linked to the condensation of ADP and phosphate to form ATP."
"F"
"Many anabolic reactions are endothermic and are linked to the (overall) hydrolysis of ATP to ADP + phosphate."
7, ATPase.bmp
"Catabolic reactions are commonly linked to hydrolysis of ATP."
"F"
"Most catabolic reactions are exothermic, and are linked (indirectly) to the condensation of ADP and phosphate to form ATP."
"Anabolic (biosynthetic reactions) are commonly linked to the condensation of ADP and phosphate to form ATP."
"T"
"Most catabolic reactions are exothermic, and are linked (indirectly) to the condensation of ADP and phosphate to form ATP."
8, ATPase.bmp
"ATPase catalyses the transfer of phosphate from ATP onto an acceptor substrate."
"F"
"ATPase catalyses hydrolysis ATP to ADP and phosphate; this may be associated with pumping of ions across a membrane. Nett phosphorylation of a substrate is the reaction catalysed by a kinase."
"A kinase catalyses the hydrolysis of ATP to ADP and phosphate."
"F"
"A kinase catalyses the transfer of phosphate from ATP onto a substrate, releasing a phosphorylated product."
9, ATPase.bmp
"ATPase catalyses the oxidation of ATP to ADP."
"F"
"ATPase catalyses hydrolysis ATP to ADP and phosphate; this may be associated with pumping of ions across a membrane."
"ATPase catalyses the reduction of ADP to ATP."
"F"
"ATPase catalyses hydrolysis ATP to ADP and phosphate; this may be associated with pumping of ions across a membrane."
10) blank.bmp
"ATP is formed only in the mitochondria."
"F"
"Although most ATP is formed in mitochondria by oxidative phosphorylation, substrate level phosphorylation in the cytosol is also important."
"ATP is formed only in the mitochondria."
"F"
"Although most ATP is formed in mitochondria by oxidative phosphorylation, substrate level phosphorylation in the cytosol is also important."
11, ATPase.bmp
"There is very much more ATP than ADP in the cell."
"T"
"The ratio of ATP : ADP in the cell is about 500 : 1; as ADP is formed by hydrolysis of ATP, so it is rapidly rephosphorylated back to ATP."
"There is very much more ADP than ATP in the cell."
"F"
"The ratio of ATP : ADP in the cell is about 500 : 1; as ADP is formed by hydrolysis of ATP, so it is rapidly rephosphorylated back to ATP."
12, ATPase.bmp
"ATP is formed by the oxidation of ADP."
"F"
"ATP is formed by phosphorylation of ADP - commonly linked to the oxidation of substrates."
"ATP is formed by the reduction of ADP."
"F"
"ATP is formed by phosphorylation of ADP - commonly linked to the oxidation of substrates."
13, blank.bmp
"Hydrophobic compounds generally enter cells by passive diffusion."
"T"
"Hydrophobic compounds are lipid soluble, and can readily dissolve in, and diffuse across, the cell membrane."
"Hydrophilic compounds generally enter cells by passive diffusion."
"F"
"Hydrophilic compounds are not lipid soluble, and cannot dissolve in, and diffuse across, the cell membrane. They require a transport protein in the cell membrane."
14, blank.bmp
"Most hydrophilic substrates can enter and leave cells freely."
"F"
"While hydrophobic compounds can dissolve in the membrane lipid and enter cells freely, hydrophilic compounds cannot, and require a membrane transport system."
"Most hydrophobic substrates can enter and leave cells freely."
"T"
"Hydrophobic compounds are lipid soluble, and can readily dissolve in, and diffuse across, the cell membrane."
15, blank.bmp
"Hydrophobic compounds require a transport protein in the cell membrane."
"F"
"Hydrophobic compounds are lipid soluble, and can readily dissolve in, and diffuse across, the cell membrane. They do not normally require a transport protein in the cell membrane."
"Hydrophilic compounds require a transport protein in the cell membrane."
"T"
"Hydrophilic compounds are not lipid soluble, and cannot dissolve in, and diffuse across, the cell membrane. They require a transport protein in the cell membrane."
16, blank.bmp
"Nett accumulation of hydrophilic compounds inside a cell, to a higher concentration that outside, can be achieved if there is an intracellular binding protein."
"T"
"A compound that diffuses across a cell membrane, whether or not it requires a membrane transport protein, will normally come to equilibrium with the same concentration on either side of the membrane. However, if the compound is bound to an intracellular binding protein, what is bound is not readily available to equilibrate across the membrane, so a higher concentration can be achieved inside the cell than outside."
"Nett accumulation of hydrophobic compounds inside a cell, to a higher concentration that outside, can be achieved if there is an intracellular binding protein."
"T"
"A compound that crosses a cell membrane by carrier-mediated diffusion will normally come to equilibrium with the same concentration on either side of the membrane. However, if the compound is bound to an intracellular binding protein, what is bound is not readily available to equilibrate across the membrane, so a higher concentration can be achieved inside the cell than outside."
17, blank.bmp
"Active transport always results in a higher concentration of the substrate inside the cell than outside."
"F"
"Active transport may involve accumulating a compound inside the cell to a higher concentration than outside or export of a compounds from a cell to achieve a greater concentration outside."
"Active transport always results in a higher concentration of the substrate on one side of the cell membrane than the other."
"T"
"Active transport may involve accumulating a compound inside the cell to a higher concentration than outside or export of a compounds from a cell to achieve a greater concentration outside."
18, blank.bmp
"Facilitated (carrier-mediated) diffusion alone cannot achieve a different concentration of the substrate inside and outside the cell."
"T"
"In facilitated diffusion the concentration of substrate will be the same on both sides of the membrane - it is a passive transport process, although there is a transport protein in the membrane to permit the hydrophilic substrate cross the hydrophobic membrane. For nett accumulation to occur the material transported must either be protein bound inside the cell or be phosphorylated (assuming that the phosphorylated derivative does not cross the cell membrane)."
"Facilitated (carrier-mediated) diffusion alone permits accumulation of a higher concentration of the substrate inside the cell than outside."
"F"
"In facilitated diffusion the concentration of substrate will be the same on both sides of the membrane - it is a passive transport process, although there is a transport protein in the membrane to permit the hydrophilic substrate cross the hydrophobic membrane. For nett accumulation to occur the material transported must either be protein bound inside the cell or be phosphorylated (assuming that the phosphorylated derivative does not cross the cell membrane)."
19, G6P.bmp
"Phosphorylation of a substrate once it has entered a cell permits accumulation of a higher concentration of the substrate inside the cell than outside."
"T"
"This is the process of metabolic trapping; if the substrate can cross the cell membrane by facilitated (carrier-mediated) diffusion, but the phosphorylated substrate cannot, then phosphorylation will permit nett accumulation of the substrate inside the cell."
"Facilitated (carrier-mediated) diffusion linked to phosphorylation of a substrate once it has entered a cell permits accumulation of a higher concentration of the substrate inside the cell than outside."
"T"
"This is the process of metabolic trapping; if the substrate can cross the cell membrane by facilitated (carrier-mediated) diffusion, but the phosphorylated substrate cannot, then phosphorylation will permit nett accumulation of the substrate inside the cell."
20, blank.bmp
"Active transport is the process of achieving a higher concentration of a substrate on one side of a cell membrane than the other, linked to the overall hydrolysis of ATP to ADP + phosphate."
"T"
"This is the definition of active transport."
"Active transport is the process of achieving a higher concentration of a substrate on one side of a cell membrane than the other, linked to the condensation of ADP + phosphate to yield ATP."
"F"
"Active transport is the process of achieving a higher concentration of a substrate on one side of a cell membrane than the other, linked to the overall hydrolysis of ATP to ADP + phosphate."
21, phosphor2.bmp
"For some substrates the role of ATP in active transport across the cell membrane can be accounted for by phosphorylation of the membrane transport protein."
"T"
"P-type transport proteins do not transport their substrate across the cell membrane unless they are phosphorylated. The carrier must also undergo dephosphorylation as the substrate is transported."
"In a P-type transporter, phosphorylation of the transport protein causes a conformational change so that it no longer transports substrate."
"F"
"Phosphorylation of a P-type transporter cases a conformational change such that the transmembrane pore is opened."
22, phosphor2.bmp
"In a P-type transporter, phosphorylation of the transport protein causes a conformational change so that it transports substrate."
"T"
"Phosphorylation of a P-type transporter cases a conformational change such that the transmembrane pore is opened."
"In a P-type transporter, phosphorylation of the transport protein causes a conformational change so that it no longer transports substrate."
"F"
"Phosphorylation of a P-type transporter cases a conformational change such that the transmembrane pore is opened."
23, ATPase.bmp
"Membrane ATPases catalyse the hydrolysis of ATP to ADP + phosphate, linked to pumping of ions across the membrane."
"T"
"Hydrolysis of ATP by membrane ATPases is linked to pumping of ions across the membrane - either exchange of sodium and potassium ions (the sodium pump) or formation of a proton (hydrogen ion) gradient across the membrane."
"Membrane ATPases catalyse the condensation of ADP + phosphate to ATP, linked to pumping of sodium and potassium ions across the membrane."
"F"
"Hydrolysis of ATP by membrane ATPases is linked to pumping of ions across the membrane - either exchange of sodium and potassium ions (the sodium pump) or formation of a proton (hydrogen ion) gradient across the membrane."
24, ATPase.bmp
"Membrane ATPases create a proton gradient across the cell membrane by pumping sodium ions across the membrane."
"F"
"The membrane ATPase creates a proton gradient by taking hydroxyl ions from outside the cell and hydrogen ions from inside the cell to catalyse the hydrolysis of ATP to ADP and phosphate."
"The proton gradient created by membrane ATPases can lead to pumping of sodium ions out of the cell in exchange for hydrogen ions re-entering."
"T"
"There is a sodium / proton antiporter in the cell membrane that permits hydrogen ions to re-enter in exchange for sodium ions."
25, muscle.bmp
"Muscle contraction involves the condensation of ADP + phosphate to ATP"
"F"
"Overall in muscle contraction ATP is hydrolysed to ADP + phosphate."
"Muscle contraction involves the hydrolysis of ATP to ADP + phosphate."
"T"
"Overall in muscle contraction ATP is hydrolysed to ADP + phosphate."
26, muscle.bmp
"Actin has ATPase activity in the light chains in the head region."
"F"
"The light chain of myosin (the head region) has ATPase activity. In myofibrils the myosin molecules are arranged with their tail regions overlapping."
"Myosin has ATPase activity in the light chains in the head region."
"T"
"The light chain of myosin (the head region) has ATPase activity. In myofibrils the myosin molecules are arranged with their tail regions overlapping."
27, muscle.bmp
"Binding of ATP to myosin causes a conformational change so that it no longer binds tightly to actin."
"T"
"Myosin with ADP bound to the head region is tightly bound to actin. When the ADP is replaced by ATP, myosin undergoes a conformational change, so that it is less tightly bound to actin."
"Binding of ATP to myosin causes a conformational change so that binds tightly to actin."
"F"
"Myosin with ADP bound to the head region is tightly bound to actin. When the ADP is replaced by ATP, myosin undergoes a conformational change, so that it is less tightly bound to actin."
28, muscle.bmp
"Binding of ATP to actin causes a conformational change so that it no longer binds tightly to myosin."
"F"
"Actin does not bind ATP. Myosin with ADP bound to the head region is tightly bound to actin. When the ADP is replaced by ATP, myosin undergoes a conformational change, so that it is less tightly bound to actin."
"Binding of ATP to actin causes a conformational change so that it no longer binds tightly to myosin."
"F"
"Actin does not bind ATP. Myosin with ADP bound to the head region is tightly bound to actin. When the ADP is replaced by ATP, myosin undergoes a conformational change, so that it is less tightly bound to actin."
29, muscle.bmp
"Hydrolysis of the ATP bound to myosin causes a conformational change - the power stroke of muscle contraction."
"T"
"Hydrolysis of the ATP by the ATPase in the head region of myosin leads to a conformational change, and movement of the head region to become associated with an actin molecule further along the tropomyosin filament. This is the power stroke of muscle contraction. Release of the phosphate, leaving ADP bound to myosin, permits tight binding of the myosin to the new actin molecule."
"Replacement of the ADP bound to myosin by ATP causes a conformational change which is the power stroke of muscle contraction."
"F"
"Myosin with ADP bound to the head region is tightly bound to actin. When the ADP is replaced by ATP, myosin undergoes a conformational change, so that it is less tightly bound to actin. Hydrolysis of the ATP by the ATPase in the head region of myosin leads to a further conformational change, and movement of the head region to become associated with an actin molecule further along the tropomyosin filament. This is the power stroke of muscle contraction."
30, linkage.bmp
"Mitochondrial oxidation of substrates cannot normally proceed in the absence of ADP."
"T"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen, and since the coenzymes are reduced, it is not possible to use them to oxidize substrates."
"Mitochondrial oxidation of substrates cannot normally proceed in the absence of ATP."
"F"
"ATP is not required for substrate oxidation in mitochondria; it is ADP that is essential, because under normal conditions there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen, and since the coenzymes are reduced, it is not possible to use them to oxidize substrates."
31, linkage.bmp
"The oxidation of substrates in the mitochondrion can proceed readily under anaerobic conditions."
"F"
"In the absence of oxygen the reduced coenzymes cannot be re-oxidized, so oxidation of substrates ceases."
"The oxidation of substrates in the mitochondrion cannot proceed under anaerobic conditions."
"T"
"In the absence of oxygen the reduced coenzymes cannot be re-oxidized, so oxidation of substrates ceases."
32, oxeltrace1.bmp
"There is uncontrolled oxidation of substrates in the presence of an inhibitor of phosphorylation of ADP to ATP, such as oligomycin."
"F"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if phosphorylation of ADP is inhibited, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen."
"There is uncontrolled oxidation of substrates in the presence of an inhibitor of electron transport, such as azide."
"F"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if phosphorylation of ADP is inhibited, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen."
33, linkage.bmp
"The rate of substrate oxidation is controlled by the utilization of ATP in chemical and physical work."
"T"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little ADP is available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen."
"The rate of ATP formation in mitochondria is controlled by the rate of substrate oxidation."
"F"
"Quite the reverse. The rate of substrate oxidation is controlled by the rate at which ATP can be formed, which is limited by the availability of ADP."
34, linkage.bmp
"Substrate oxidation is obligatorily linked to oxygen consumption and formation of ATP under normal conditions."
"T"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria."
"The oxidation of substrates in the mitochondrion can proceed readily in the absence of ADP."
"F"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little ADP is available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen."
35, oxeltrace1.bmp
"There is uncontrolled oxidation of substrates in the presence of an inhibitor of electron transport, such as rotenone."
"F"
"If electron transport is inhibited then reduced coenzymes cannot be oxidized, and there will be no utilization of oxygen."
"Oxygen consumption is inhibited by a high ATP : ADP ratio in tightly coupled mitochondria."
"T"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little ADP is available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen."
36, oxeltrace1.bmp
"There is a constant ratio of ATP formed : oxygen consumed, regardless of the substrate being oxidized."
"F"
"Substrates that reduce flavins yield ~2 ATP per atom of oxygen consumed, while substrates that reduce NAD yield ~3 ATP per atom of oxygen consumed."
"There is uncontrolled utilization of oxygen in the presence of an uncoupler such as dinitrophenol."
"T"
"An uncoupler discharges the proton gradient, and permits oxidation of substrates and consumption of oxygen uncontrolled by the availability of ADP."
37, oxeltrace1.bmp
"There is no utilization of oxygen in the presence of an uncoupler such as dinitrophenol."
"F"
"An uncoupler discharges the proton gradient, and permits oxidation of substrates and consumption of oxygen uncontrolled by the availability of ADP."
"There is uncontrolled utilization of oxygen in the presence of an inhibitor of electron transport, such as cyanide."
"F"
"If electron transport is inhibited then reduced coenzymes cannot be oxidized, and there will be no utilization of oxygen."
38, linkage.bmp
"The rate of oxygen consumption by mitochondria is normally controlled by the availability of substrates to be oxidized."
"F"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen, and since the coenzymes are reduced, it is not possible to use them to oxidize substrates."
"Substrate oxidation can never occur in mitochondria unless phosphorylation of ADP to ATP is also proceeding."
"F"
"An uncoupler such as dinitrophenol discharges the proton gradient, and permits oxidation of substrates and consumption of oxygen uncontrolled by the availability of ADP."
39, crista.bmp
"Enzymes in the mitochondrial crista membrane catalyse the oxidation of reduced coenzymes, linked to reduction of oxygen to water"
"T"
"The electron transport chain is in the crista membrane, and catalyses the oxidation of reduced coenzymes, ultimately reducing oxygen to water."
"Enzymes in the mitochondrial outer membrane catalyse the oxidation of reduced coenzymes, linked to reduction of oxygen to water"
"F"
"The electron transport chain is in the crista membrane, and catalyses the oxidation of reduced coenzymes, ultimately reducing oxygen to water."
40, crista.bmp
"Enzymes in the mitochondrial matrix catalyse the formation of ATP from ADP and phosphate."
"F"
"The matrix contains the enzymes involved in fatty acid oxidation and the citric acid cycle. The synthesis of ATP occurs in the primary particles, which are attached to the inner face of the crista membrane."
"The crista membrane contains the electron transport chain"
"T"
"The electron transport chain is in the crista membrane, and catalyses the oxidation of reduced coenzymes, ultimately reducing oxygen to water."
41, crista.bmp
"Enzymes in the mitochondrial primary particles catalyse the oxidation of reduced coenzymes, linked to reduction of oxygen to water."
"F"
"The primary particles contain the ATP synthase, which catalyses the formation of ATP from ADP and phosphate. This is dependent on the trans-membrane proton gradient. The oxidation of reduced coenzymes occurs in the inner mitochondrial membrane."
"The mitochondrial primary particles contains the electron transport chain"
"F"
"The primary particles contain the ATP synthase, which catalyses the formation of ATP from ADP and phosphate. This is dependent on the trans-membrane proton gradient. The electron transport chain is in the crista membrane, and catalyses the oxidation of reduced coenzymes, ultimately reducing oxygen to water."
42, crista.bmp
"Enzymes in the mitochondrial inter-membrane space catalyse the oxidation of reduced coenzymes, linked to reduction of oxygen to water."
"F"
"The inter-membrane space contains a variety of enzymes involved in nucleotide metabolism and transamination of amino acids."
"Enzymes in the mitochondrial inter-membrane space catalyse the formation of ATP from ADP and phosphate."
"F"
"The primary particles contain the ATP synthase, which catalyses the formation of ATP from ADP and phosphate. This is dependent on the trans-membrane proton gradient. The inter-membrane space contains a variety of enzymes involved in nucleotide metabolism and transamination of amino acids."
43, crista.bmp
"The inner mitochondrial membrane provides a permeability barrier to control the uptake of substrates for oxidation."
"T"
"The outer mitochondrial membrane is freely permeable to most substrates; it is the inner membrane which regulates the uptake of substrates for oxidation."
"The outer mitochondrial membrane provides a permeability barrier to control the uptake of substrates for oxidation."
"F"
"The outer mitochondrial membrane is freely permeable to most substrates; it is the inner membrane which regulates the uptake of substrates for oxidation."
44, blank.bmp
"Both cytochromes and non-haem iron proteins act as single electron carriers in the mitochondrial electron transport chain."
"T"
"Iron carriers (the cytochromes, which contain haem, and the non-haem iron proteins) must undergo single electron reactions, even when a non-haem iron protein contains more than one reactive iron atom."
"Both cytochromes and non-haem iron proteins act as hydrogen carriers in the mitochondrial electron transport chain."
"F"
"Iron carriers (the cytochromes, which contain haem, and the non-haem iron proteins) must undergo single electron reactions, without an associated proton."
45, blank.bmp
"Non-haem iron proteins transport electrons but not protons."
"T"
"Iron carriers (the cytochromes, which contain haem, and the non-haem iron proteins) carry electrons only."
"Ubiquinone (coenzyme Q) transports both electrons and protons."
"T"
"Organic carriers such as NAD, flavins and ubiquinone transport both protons and electrons."
46, blank.bmp
"Cytochromes transport protons but not electrons."
"F"
"Iron carriers (the cytochromes, which contain haem, and the non-haem iron proteins) carry electrons only."
"Non-haem iron proteins may undergo one-electron or two-electron reduction reactions."
"F"
"Iron carriers (the cytochromes, which contain haem, and the non-haem iron proteins) must undergo single electron reactions, even when a non-haem iron protein contains more than one reactive iron atom."
47, blank.bmp
"NAD may undergo one-electron or two-electron reduction reactions."
"F"
"NAD can only undergo a two electron reduction, while flavins and ubiquinone can undergo their two electron reaction in two single electron steps."
"Ubiquinone (coenzyme Q) transports protons but not electrons."
"F"
"Organic carriers such as NAD, flavins and ubiquinone transport both protons and electrons."
48, blank.bmp
"Flavoproteins may undergo one-electron or two-electron reduction reactions."
"T"
"Flavins and ubiquinone can undergo their two electron reaction in two single electron steps."
"Cytochromes may undergo one-electron or two-electron reduction reactions."
"F"
"Iron carriers (the cytochromes, which contain haem, and the non-haem iron proteins) must undergo single electron reactions."
49, blank.bmp
"Flavoproteins transport protons but not electrons."
"F"
"Organic carriers such as NAD, flavins and ubiquinone transport both protons and electrons."
"Flavoproteins transport both electrons and protons."
"T"
"Organic carriers such as NAD, flavins and ubiquinone transport both protons and electrons."
50, blank.bmp
"When a hydrogen carrier reduces an electron carrier, a proton is expelled into the crista space."
"T"
"When a hydrogen carrier (NAD, a flavin or ubiquinone) reduces an electron carrier (a cytochrome or non-haem iron protein), there is a proton to be accounted for. This is expelled from the outer face of the membrane, into the crista space."
"When a hydrogen carrier reduces an electron carrier, a proton is expelled into the mitochondrial matrix."
"F"
"The proton is expelled from the outer face of the membrane, into the crista space."
51, blank.bmp
"When an electron carrier reduces a hydrogen carrier, a proton is expelled into the crista space."
"F"
"When an electron carrier reduces a hydrogen carrier, a proton must be found to accompany the electron. This is acquired from water at the inner face of the membrane, thus leading to an accumulation of hydroxyl ions in the matrix."
"When an electron carrier reduces a hydrogen carrier, a proton is acquired from the mitochondrial matrix."
"T"
"When an electron carrier reduces a hydrogen carrier, a proton must be found to accompany the electron. This is acquired from water at the inner face of the membrane, thus leading to an accumulation of hydroxyl ions in the matrix."
52, dnp.bmp
"If the proton gradient across the mitochondrial inner membrane is discharged by a weak acid then electron transport ceases."
"F"
"The proton gradient across the crista membrane provides the driving force for the phosphorylation of ADP to ATP. If this proton gradient is discharged by a weak acid (such as dinitrophenol), then not only can ATP not be formed, but the normal tight regulation of oxygen consumption and substrate oxidation by the availability of ADP is broken. In the presence of such a compound (an uncoupler), there is uncontrolled utilization of oxygen."
"If the proton gradient across the mitochondrial inner membrane is discharged by a weak acid then electron transport increases considerably."
"T"
"The proton gradient across the crista membrane provides the driving force for the phosphorylation of ADP to ATP. If this proton gradient is discharged by a weak acid (such as dinitrophenol), then not only can ATP not be formed, but the normal tight regulation of oxygen consumption and substrate oxidation by the availability of ADP is broken. In the presence of such a compound (an uncoupler), there is uncontrolled utilization of oxygen."
53, oxeltrace3.bmp
"The ratio of ATP formed : oxygen consumed (the P : O ratio) is always the same, regardless of which substrate is being oxidized."
"F"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
"The ratio of ATP formed : oxygen consumed (the P : O ratio) is depends on which substrate is being oxidized."
"T"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
54, blank.bmp
"Some inhibitors of the electron transport chain, such as rotenone, prevent the oxidation of substrates that reduce NAD, but not the oxidation of substrates that reduce flavoproteins."
"T"
"Different inhibitors act at different points in the electron transport chain."
"Some inhibitors of the electron transport chain, such as cyanide, prevent the oxidation of all substrates, whether they reduce NAD or flavoproteins."
"T"
"Different inhibitors act at different points in the electron transport chain. Cyanide inhibits cytochrome oxidase, the last electron carrier, and so inhibits the oxidation of any substrate."
55, dnp.bmp
"If ATP synthesis has been inhibited by oligomycin, addition of an uncoupler such as dinitrophenol permits more or less complete consumption of all the oxygen available regardless of the amount of ADP present."
"T"
"An uncoupler such as dinitrophenol will permit uncontrolled oxidation of substrates, and hence consumption of oxygen, regardless of whether or not ATP synthesis has been inhibited by oligomycin."
"If ATP synthesis has been inhibited by oligomycin, addition of an uncoupler such as dinitrophenol does not permit any utilization of oxygen."
"F"
"An uncoupler such as dinitrophenol will permit uncontrolled oxidation of substrates, and hence consumption of oxygen, regardless of whether or not ATP synthesis has been inhibited by oligomycin."
56, blank.bmp
"The proton gradient across the mitochondrial inner membrane is essential for the phosphorylation of ADP to ATP."
"T"
"The proton gradient across the crista membrane provides the driving force for the phosphorylation of ADP to ATP. If this proton gradient is discharged by a weak acid (such as dinitrophenol), then ATP cannot be formed."
"The proton gradient across the mitochondrial inner membrane is produced by the hydrolysis of ATP to ADP and phosphate."
"F"
"The proton gradient across the crista membrane is formed by electron transport. It provides the driving force for the phosphorylation of ADP to ATP. If this proton gradient is discharged by a weak acid (such as dinitrophenol), then ATP cannot be formed."
57, oxeltrace3.bmp
"Substrates that reduce NAD lead to formation of more ATP per mol oxygen than do substrates that reduce flavoproteins."
"T"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
 "The ratio of ATP formed : oxygen consumed (the P : O ratio) for substrates that reduce NAD is approximately 2."
"F"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
58, oxeltrace3.bmp
"The ratio of ATP formed : oxygen consumed (the P : O ratio) for substrates that reduce NAD is approximately 3."
"T"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
"The ratio of ATP formed : oxygen consumed (the P : O ratio) for substrates that reduce flavoproteins is approximately 2."
"T"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
59, oxeltrace3.bmp
"The ratio of ATP formed : oxygen consumed (the P : O ratio) for substrates that reduce flavoproteins is approximately 3."
"F"
"One of the protons that is expelled into the inter-membrane space arises in the series of reactions between NAD and ubiquinone; by contrast, flavins reduce ubiquinone directly. This means that there is an additional site for generation of the proton gradient when substrates reduce NAD, and hence more ATP is produced per mol of oxygen consumed. The P : O ratio is approximately 3 when substrates reduce NAD, and approximately 2 when they reduce a flavin."
"If electron transport has been inhibited by cyanide, addition of an uncoupler such as dinitrophenol permits more or less complete consumption of all the oxygen available regardless of the amount of ADP present."
"F"
"If electron transport has been inhibited then regardless of whether or not an uncoupler is present it is not possible to utilize oxygen."
60, oxeltrace2.bmp
 "The diagram shows oxygen consumption by mitochondria incubated with malate and varying amounts of ADP. Line P shows the results from the experiment with the greatest amount of ADP added"
"F"
" Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen. Therefore, the line showing the steepest rate of oxygen utilization must be the one from the experiment using the highest concentration of ADP - line Q."
"The diagram shows oxygen consumption by mitochondria incubated with malate and varying amounts of ADP. Line Q shows the results from the experiment with the greatest amount of ADP added"
"T"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen. Therefore, the line showing the steepest rate of oxygen utilization must be the one from the experiment using the highest concentration of ADP - line Q."
61, oxeltrace2.bmp
"The diagram shows oxygen consumption by mitochondria incubated with malate and varying amounts of ADP. Line Q shows the results from the experiment with the smallest amount of ADP added"
"F"
"Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen. Therefore, the line showing the slowest rate of oxygen utilization must be the one from the experiment using the lowest concentration of ADP - line P."
"The diagram shows oxygen consumption by mitochondria incubated with malate and varying amounts of ADP. Line P the results from the experiment with the smallest amount of ADP added"
"T"
" Under normal conditions, there is tight, and obligatory, coupling of electron transport and phosphorylation of ADP to ATP in the mitochondria. This means that if there is little or no ADP available, reduced coenzymes cannot be re-oxidized. Therefore there is little or no consumption of oxygen. Therefore, the line showing the slowest rate of oxygen utilization must be the one from the experiment using the lowest concentration of ADP - line P."
62, oxeltrace3.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with a constant amount of ADP, and either malate or succinate. Line P shows the results from the experiment with malate."
 "T"
"The same amount of oxygen is consumed whether malate or succinate is the substrate. However, more protons are pumped across the crista membrane when malate (which reduces NAD) is oxidized than when succinate (which reduces a flavoprotein) is oxidized. Therefore more ADP is phosphorylated to ATP when malate is oxidized than when succinate is oxidized. This means that less oxygen is consumed before all of the ADP has been used when malate is the substrate. Line P represents less oxygen used for phosphorylation of all the ADP provided, and so must represent the experiment in which malate was the substrate."
"The diagram shows the consumption of oxygen by mitochondria incubated with a constant amount of ADP, and either malate or succinate. Line Q the results from the experiment with malate."
"F"
"The same amount of oxygen is consumed whether malate or succinate is the substrate. However, more protons are pumped across the crista membrane when malate (which reduces NAD) is oxidized than when succinate (which reduces a flavoprotein) is oxidized. Therefore more ADP is phosphorylated to ATP when malate is oxidized than when succinate is oxidized. This means that less oxygen is consumed before all of the ADP has been used when malate is the substrate. Line P represents less oxygen used for phosphorylation of all the ADP provided, and so must represent the experiment in which malate was the substrate."
63, oxeltrace3.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with a constant amount of ADP, and either malate or succinate. Line Q the results from the experiment with succinate."
"T"
"The same amount of oxygen is consumed whether malate or succinate is the substrate. However, more protons are pumped across the crista membrane when malate (which reduces NAD) is oxidized than when succinate (which reduces a flavoprotein) is oxidized. Therefore more ADP is phosphorylated to ATP when malate is oxidized than when succinate is oxidized. This means that less oxygen is consumed before all of the ADP has been used when malate is the substrate. Line Q represents more oxygen used for phosphorylation of all the ADP provided, and so must represent the experiment in which succinate was the substrate."
"The diagram shows the consumption of oxygen by mitochondria incubated with a constant amount of ADP, and either malate or succinate. Line P the results from the experiment with succinate."
"F"
"The same amount of oxygen is consumed whether malate or succinate is the substrate. However, more protons are pumped across the crista membrane when malate (which reduces NAD) is oxidized than when succinate (which reduces a flavoprotein) is oxidized. Therefore more ADP is phosphorylated to ATP when malate is oxidized than when succinate is oxidized. This means that less oxygen is consumed before all of the ADP has been used when malate is the substrate. Line Q represents more oxygen used for phosphorylation of all the ADP provided, and so must represent the experiment in which succinate was the substrate."
64, oxeltrace4.bmp
 "The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compound X. Compound X is an inhibitor of electron transport."
"F"
"An inhibitor of electron transport would reduce the utilization of oxygen, probably to near zero. What compound X does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compound X. Compound X is an inhibitor of ATP synthase."
"F"
"In normally coupled mitochondria there is obligatory linkage between electron transport, oxygen consumption and ATP formation. Therefore inhibition of ATP synthesis would reduce the consumption of oxygen to no more than occurred before the ADP was added. What compound X does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
65, oxeltrace4.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compound X. Compound X inhibits the transport of ADP into mitochondria."
"F"
"In normally coupled mitochondria there is obligatory linkage between electron transport, oxygen consumption and ATP formation. Therefore inhibition of ADP transport into mitochondria would reduce the consumption of oxygen to no more than occurred before the ADP was added. What compound X does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compound X. Compound X is an uncoupler."
"T"
"Compound X increases the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
66, oxeltrace5.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an inhibitor of electron transport."
"F"
"An inhibitor of electron transport would reduce the utilization of oxygen, probably to near zero. What compound Y does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an inhibitor of ATP synthase."
"F"
"In normally coupled mitochondria there is obligatory linkage between electron transport, oxygen consumption and ATP formation. Therefore inhibition of ATP synthesis would reduce the consumption of oxygen to no more than occurred before the ADP was added. What compound Y does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
67, oxeltrace5.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y inhibits the transport of ADP into mitochondria."
"F"
"In normally coupled mitochondria there is obligatory linkage between electron transport, oxygen consumption and ATP formation. Therefore inhibition of ADP transport into mitochondria would reduce the consumption of oxygen to no more than occurred before the ADP was added. What compound Y does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an uncoupler."
"T"
"Compound Y increases the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
68, oxeltrace5.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X is an inhibitor of the electron transport chain."
"T"
"Addition of compound X causes more or less complete inhibition of oxygen consumption, and addition of compound Y, which is an uncoupler, does not relieve this inhibition. An uncoupler permits rapid electron transport and more or less complete utilization of oxygen, uncontrolled by the availability of ADP. Since the uncoupler does not relieve the inhibition of oxygen utilization caused by compound X, then X must inhibit electron transport."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X is an inhibitor of ATP synthase."
"F"
"Addition of compound X causes more or less complete inhibition of oxygen consumption, and addition of compound Y, which is an uncoupler, does not relieve this inhibition. An uncoupler permits rapid electron transport and more or less complete utilization of oxygen, uncontrolled by the availability of ADP. Since the uncoupler does not relieve the inhibition of oxygen utilization caused by compound X, then X must inhibit the electron transport chain, not ATP synthase."
69, oxeltrace5.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X inhibits the transport of ADP into mitochondria."
"F"
"Addition of compound X causes more or less complete inhibition of oxygen consumption, and addition of compound Y, which is an uncoupler, does not relieve this inhibition. An uncoupler permits rapid electron transport and more or less complete utilization of oxygen, uncontrolled by the availability of ADP. Since the uncoupler does not relieve the inhibition of oxygen utilization caused by compound X, then X must inhibit the electron transport chain, not the uptake of ADP into the mitochondria."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X inhibits the transport of ADP into mitochondria."
"F"
"Addition of compound X causes more or less complete inhibition of oxygen consumption, and addition of compound Y, which is an uncoupler, does not relieve this inhibition. An uncoupler permits rapid electron transport and more or less complete utilization of oxygen, uncontrolled by the availability of ADP. Since the uncoupler does not relieve the inhibition of oxygen utilization caused by compound X, then X must inhibit the electron transport chain, not the uptake of ADP into the mitochondria."
70, oxeltrace6.bmp
 "The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an inhibitor of electron transport."
"F"
"An inhibitor of electron transport would reduce the utilization of oxygen, probably to near zero. What compound Y does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an inhibitor of ATP synthase."
"F"
"In normally coupled mitochondria there is obligatory linkage between electron transport, oxygen consumption and ATP formation. Therefore inhibition of ATP synthesis would reduce the consumption of oxygen to no more than occurred before the ADP was added. What compound Y does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
71, oxeltrace6.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y inhibits the transport of ADP into mitochondria."
"F"
"In normally coupled mitochondria there is obligatory linkage between electron transport, oxygen consumption and ATP formation. Therefore inhibition of ADP transport into mitochondria would reduce the consumption of oxygen to no more than occurred before the ADP was added. What compound Y does is to increase the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an uncoupler"
"T"
"Compound Y increases the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
72, oxeltrace6.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X is an inhibitor of the electron transport chain"
"F"
"Addition of compound X inhibits oxygen consumption, so that no more oxygen is used than before ADP was added. Addition of compound Y, which is an uncoupler, permits more or less complete utilization of oxygen, uncontrolled by the amount of ADP added. Therefore compound X cannot inhibit the electron transport chain (since no electron transport an no oxygen utilization could occur, with or without the uncoupler). Compound X must inhibit either ATP synthase or the uptake of ADP into the mitochondria."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X may be an inhibitor of ATP synthase."
"T"
"Addition of compound X inhibits oxygen consumption, so that no more oxygen is used than before ADP was added. Addition of compound Y, which is an uncoupler, permits more or less complete utilization of oxygen, uncontrolled by the amount of ADP added. Therefore compound X cannot inhibit the electron transport chain (since no electron transport an no oxygen utilization could occur, with or without the uncoupler). Compound X must inhibit either ATP synthase or the uptake of ADP into the mitochondria."
73, oxeltrace6.bmp
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound X may inhibit the transport of ADP into mitochondria."
"T"
"Addition of compound X inhibits oxygen consumption, so that no more oxygen is used than before ADP was added. Addition of compound Y, which is an uncoupler, permits more or less complete utilization of oxygen, uncontrolled by the amount of ADP added. Therefore compound X cannot inhibit the electron transport chain (since no electron transport an no oxygen utilization could occur, with or without the uncoupler). Compound X must inhibit either ATP synthase or the uptake of ADP into the mitochondria."
"The diagram shows the consumption of oxygen by mitochondria incubated with ADP and malate, with or without the addition of compounds X and Y. Compound Y is an uncoupler"
"T"
"Compound Y increases the consumption of oxygen very considerably, so that more or less all of the available oxygen is consumed, very rapidly, and uncontrolled by the amount of ADP available. This is the action of an uncoupler."
74, ATPase.bmp
"In ATP-requiring enzyme reactions, the substrate is always phosphorylated during the course of the reaction."
"F"
"Overall, when ATP is involved in an endothermic (endergonic) enzyme-catalysed reaction, what is observed is hydrolysis of ATP to ADP and phosphate. However, although this is the overall reaction of ATP, it proceeds in two separate stages. Commonly, either the enzyme or the substrate is phosphorylated as the first stage of the reaction, with the release of ADP, then in a later stage of the reaction the phosphate is released. In some reactions the substrate may be adenylated, with release of pyrophosphate, in the first stage of the reaction."
"In ATP-requiring enzyme reactions, the enzyme is always phosphorylated during the course of the reaction."
"F"
"Overall, when ATP is involved in an endothermic (endergonic) enzyme-catalysed reaction, what is observed is hydrolysis of ATP to ADP and phosphate. However, although this is the overall reaction of ATP, it proceeds in two separate stages. Commonly, either the enzyme or the substrate is phosphorylated as the first stage of the reaction, with the release of ADP, then in a later stage of the reaction the phosphate is released. In some reactions the substrate may be adenylated, with release of pyrophosphate, in the first stage of the reaction."
75, blank.bmp
"Cotransport of sodium and a substrate permits active transport of the substrate across a cell membrane."
"T"
"Membrane ATPases create a proton gradient across the membrane. Protons then re-enter the cell in exchange for sodium ions, so creating a sodium gradient across the membrane. In turn, this sodium gradient may be associated with uptake of substrates (by co-transport) or export of materials (by counter-transport)."
"Counter-transport of sodium and a substrate permits active export of compounds synthesised in the cell."
"T"
"Membrane ATPases create a proton gradient across the membrane. Protons then re-enter the cell in exchange for sodium ions, so creating a sodium gradient across the membrane. In turn, this sodium gradient may be associated with uptake of substrates (by co-transport) or export of materials (by counter-transport)."
-999
copyright David A Bender 2002

