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Biochemistry Exam 4 > Exam 4 ch. 23 Citric Acid Cycle > Flashcards

Exam 4 ch. 23 Citric Acid Cycle Flashcards

1
Q

The ___ ___ ___ is a series of reactions that connects the intermediate acetyl CoA from the catabolic pathways in stage 2 with electron transport and the synthesis of ATP in stage 3

A

Citric Acid Cycle

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2
Q

The Citric Acid Cycle:

operates under (aerobic or anaerobic) conditions

A

Aerobic

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3
Q

The Citric Acid Cycle:

oxidizes the two-carbon acetyl group in acetyl CoA to ___

A

CO2

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4
Q

The Citric Acid Cycle:

produces reduced coenzymes ___ and ___

A

NADH and FADH2

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5
Q

The Citric Acid Cycle:

is named for the six-carbon citrate ion from citric acid (C6H8O7), a ___ __, formed in the first reaction

A

Tricarboxylic acid

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6
Q

In the citric acid cycle,

six carbons move through the citric acid cycle, producing ____ and 2CO2

A

Oxaloacetate

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7
Q

In the citric acid cycle, each turn contains __(#) oxidation reactions producing the reduced coenzymes NADH and FADH2.

A

Four

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8
Q

In the citric acid cycle, one ___ (converted to ___ in the cell) is produced during the citric acid cycle

A

GTP (converted to ATP)

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9
Q

In the citric acid cycle, ___ (#) reactions oxidize acetyl CoA from ____ or fatty acids, producing CO2 and the high-energy compounds FADH2, NADH, and GTP

A

In the citric acid cycle, eight reactions oxidize acetyl CoA from pyruvate or fatty acids, producing CO2 and the high-energy compounds FADH2, NADH, and GTP

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10
Q

Reactions involved in the citric acid cycle include condensation, dehydration, hydration, oxidation, reduction, and hydrolysis

A

Citric Acid Cycle reactions:

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11
Q

Reaction 1:
In the first reaction of the citric acid cycle,
citrate synthase catalyzes the _____ of an acetyl group (2C) from acetyl CoA with oxaloacetate (4C) to yield ____ and ____

A

In the first reaction of the citric acid cycle,
citrate synthase catalyzes the condensation of an acetyl group (2C) from acetyl CoA with oxaloacetate (4C) to yield citrate (6C) and coenzyme A

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12
Q

Reaction 1:
In the first reaction fo the citric acid cycle, the energy to form citrate is provided by the _____ of the high-energy thioester bond in acetyl CoA

A

the energy to form citrate is provided by the hydrolysis of the high-energy thioester bond in acetyl CoA

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13
Q

Reaction 1:
In the first reaction fo the citric acid cycle, the energy to form citrate is provided by the _____ of the high-energy thioester bond in acetyl CoA

A

Reaction 1:
In the first reaction fo the citric acid cycle, the energy to form citrate is provided by the hydrolysis of the high-energy thioester bond in acetyl CoA

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14
Q

Reaction 2: Isomerazation

In reaction 2 of the citric acid cycle, aconitase catalyzes the ____ of citrate (tertiary alcohol) to yield cis-aconitate, followed by a ____ that forms isocitrate

A

In reaction 2 of the citric acid cycle, aconitase catalyzes the dehydration of citrate (tertiary alcohol) to yield cis-aconitate, followed by a hydration that forms isocitrate.

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15
Q

In reaction 2 of the citric acid cycle, aconitase catalyzes the ____ of citrate (tertiary alcohol) to yield cis-aconitate, followed by a ____ that forms isocitrate

A

In reaction 2 of the citric acid cycle, aconitase catalyzes the dehydration of citrate (tertiary alcohol) to yield cis-aconitate, followed by a hydration that forms isocitrate.

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16
Q

In reaction 3, isocitrate undergoes decarboxylation by isocitrate dehydrogenase.

One carbon is removed by converting a ___ ___ to CO2

A

In reaction 3, isocitrate undergoes decarboxylation by isocitrate dehydrogenase.

One carbon is removed by converting a carboxylate group (COO−) to CO2

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17
Q

In reaction 3, isocitrate undergoes decarboxylation by isocitrate dehydrogenase.

The ____ removes hydrogen ions and electrons, used to reduce NAD+ to NADH and H+.

A

In reaction 3, isocitrate undergoes decarboxylation by isocitrate dehydrogenase.

The dehydrogenase removes hydrogen ions and electrons, used to reduce NAD+ to NADH and H

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18
Q

In reaction 4, catalyzed by α-ketoglutarate dehydrogenase, α-ketoglutarate (5C) undergoes ____ to yield (4C) succinyl CoA.

A

In reaction 4, catalyzed by α-ketoglutarate dehydrogenase, α-ketoglutarate (5C) undergoes decarboxylation to yield (4C) succinyl CoA.

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19
Q

In reaction 4, catalyzed by α-ketoglutarate dehydrogenase,
____ of the thiol group (—SH) in HS—CoA provides hydrogen that is transferred to NAD+ to form a second molecule of NADH and H+.

A

In reaction 4, catalyzed by α-ketoglutarate dehydrogenase, oxidation of the thiol group (—SH) in HS—CoA provides hydrogen that is transferred to NAD+ to form a second molecule of NADH and H+.

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20
Q

In reaction 5, catalyzed by succinyl CoA synthetase, hydrolysis of the ___ ___ in succinyl CoA yields succinate and HS—CoA.

A

In reaction 5, catalyzed by succinyl CoA synthetase, hydrolysis of the thioester bond in succinyl CoA yields succinate and HS—CoA.

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21
Q

In reaction 5, catalyzed by succinyl CoA synthetase, energy from hydrolysis is transferred to the ____ of phosphate and GDP forming ___, a high-energy compound similar to ATP

A

In reaction 5, catalyzed by succinyl CoA synthetase, energy from hydrolysis is transferred to the condensation of phosphate and GDP forming GTP, a high-energy compound similar to ATP

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22
Q

In reaction 6, catalyzed by succinate dehydrogenase, succinate is ____ to fumarate, a compound with a C = C bond.

A

In reaction 6, catalyzed by succinate dehydrogenase, succinate is oxidized to fumarate, a compound with a C=C bond.

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23
Q

In reaction 6, catalyzed by succinate dehydrogenase, 2H lost from succinate are used to reduce the coenzyme ___ to ___

A

In reaction 6, catalyzed by succinate dehydrogenase, 2H lost from succinate are used to reduce the coenzyme FAD to FADH2

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24
Q

In reaction 7, catalyzed by fumarase, ___ is added to the double bond of fumarate to yield malate, a ___ ___

A

In reaction 7, catalyzed by fumarase, water is added to the double bond of fumarate to yield malate, a secondary alcohol

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25
Q

In reaction 8, catalyzed by malate dehydrogenase, the hydroxyl group in malate is ____ to a carbonyl group, yielding oxaloacetate.

A

In reaction 8, catalyzed by malate dehydrogenase,

the hydroxyl group in malate is oxidized to a carbonyl group, yielding oxaloacetate.

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26
Q

In reaction 8, catalyzed by malate dehydrogenase,

oxidation provides hydrogen ions and electrons for the ____ of NAD+ to NADH and H+.

A

In reaction 8, catalyzed by malate dehydrogenase,

oxidation provides hydrogen ions and electrons for the reduction of NAD+ to NADH and H+.

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27
Q

Reaction 1: Formation of

A

R1: Formation of Citrate

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28
Q

Reaction 2:

A

R2: Isomerization

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29
Q

Reaction 3:

A

R3: Oxidation, Decarboxylation

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30
Q

Reaction 4:

A

R4: Decarboxylation, Oxidation

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31
Q

Reaction 5:

A

R5: Hydrolysis

32
Q

Reaction 6:

A

R6: Oxidation

33
Q

Reaction 7:

A

R7: Hydration

34
Q

Reaction 8:

A

R8: Oxidation

35
Q

The reaction rate for the citric acid cycle

increases when low levels of ATP activate ___ ___.

A

The reaction rate for the citric acid cycle

increases when low levels of ATP activate isocitrate dehydrogenase.

36
Q

The reaction rate for the citric acid cycle

decreases when high levels of ATP or NADH inhibit ___ ___ (first step in cycle).

A

The reaction rate for the citric acid cycle

decreases when high levels of ATP or NADH inhibit citrate synthase (first step in cycle).

37
Q

In the citric acid cycle,
an acetyl group bonds with oxaloacetate to form ____.

two decarboxylations remove two carbons as two CO2.

four oxidations provide hydrogen for __# NADHs and __# FADH2.

a direct phosphorylation forms ___ (___).

A

In the citric acid cycle,
an acetyl group bonds with oxaloacetate to form citrate.

two decarboxylations remove two carbons as two CO2.

four oxidations provide hydrogen for three NADHs and one FADH2.

a direct phosphorylation forms GTP (ATP).

38
Q

How many CO2 are produced in one turn of Citric Acid Cycle:

A

2 CO2

39
Q

How many NADH are produced in one turn of Citric Acid Cycle

A

3 NADH

40
Q

How many FADH2 are produced in one turn of Citric Acid Cycle

A

1 FADH2

41
Q

How many GTP are produced in one turn of Citric Acid Cycle

A

1 GTP

42
Q

The reduced coenzymes NADH and FADH2 produced from glycolysis, oxidation of pyruvate, and the citric acid cycle are oxidized to provide the energy for the synthesis of ___

A

The reduced coenzymes NADH and FADH2 produced from glycolysis, oxidation of pyruvate, and the citric acid cycle are oxidized to provide the energy for the synthesis of ATP

43
Q

In ___ ____ or the respiratory chain,
hydrogen ions and electrons from NADH and FADH2 are passed from one electron acceptor or carrier to the next until they combine with oxygen to form H2O

A

Electron Transport

44
Q

energy released during electron transport is used to synthesize ___ from ADP and Pi during oxidative phosphorylation

A

ATP

45
Q

In the electron transport system,
there are five protein complexes, which are numbered as I, II, III, IV, and V.

two electron carriers, ___ _, and ____, attached to the inner membrane of the mitochondrion, carry electrons among these protein complexes bound to the inner membrane.

A

Coenzyme Q

Cytochrome c,

46
Q

In electron transport, the oxidation of NADH and FADH2 provides ____ ions and electrons that eventually react with oxygen to form water.

A

Hydrogen

47
Q

In complex I,
electron transport begins when hydrogen ions and electrons are transferred from ____ to complex I.

loss of hydrogen from NADH regenerates NAD+ to ____ more substrates in oxidative pathways such as the citric acid cycle.

hydrogen ions and electrons are transferred to the mobile electron carrier ___, forming CoQH2.

CoQH2 carries electrons from complexes I and II to complex III.

A

In complex I,
electron transport begins when hydrogen ions and electrons are transferred from NADH to complex I.
loss of hydrogen from NADH regenerates NAD+ to oxidize more substrates in oxidative pathways such as the citric acid cycle.
hydrogen ions and electrons are transferred to the mobile electron carrier CoQ, forming CoQH2.
CoQH2 carries electrons from complexes I and II to complex III.

48
Q

During electron transfer,
H+ ions are pumped through complex I into the intermembrane space, producing a reservoir of H+ (___ __ ___).

for every __# electrons that pass from NADH to CoQ, 4H+ are pumped across the mitochondrial membrane, producing a charge separation on opposite sides of the membrane.

A

During electron transfer,
H+ ions are pumped through complex I into the intermembrane space, producing a reservoir of H+ (hydrogen ion gradient).

for every two electrons that pass from NADH to CoQ, 4H+ are pumped across the mitochondrial membrane, producing a charge separation on opposite sides of the membrane.

49
Q

Complex II consists of the enzyme ___ ____ from the citric acid cycle.

In complex II,
CoQ obtains hydrogen and electrons directly from FADH2. This produces CoQH2 and regenerates the oxidized coenzyme ___, which becomes available to oxidize more substrates.

A

Complex II consists of the enzyme succinate dehydrogenase from the citric acid cycle.

In complex II,
CoQ obtains hydrogen and electrons directly from FADH2. This produces CoQH2 and regenerates the oxidized coenzyme FAD, which becomes available to oxidize more substrates.

50
Q

Complex II consists of the enzyme ___ ____ from the citric acid cycle.

In complex II,
CoQ obtains hydrogen and electrons directly from FADH2 and becomes CoQH2.

two electrons are transferred from the mobile carrier CoQH2 to a series of iron-containing proteins called _____.

electrons are then transferred to two cytochrome c, which can move between complexes III and IV.

A

Complex II consists of the enzyme succinate dehydrogenase from the citric acid cycle.

In complex II,
CoQ obtains hydrogen and electrons directly from FADH2 and becomes CoQH2.

two electrons are transferred from the mobile carrier CoQH2 to a series of iron-containing proteins called cytochromes.

electrons are then transferred to two cytochrome c, which can move between complexes III and IV.

51
Q

Cytochrome c

contains Fe3+/Fe2+, which is reduced to Fe2+ and oxidized to Fe3+.

generates energy from electron transfer to pump 4H+ from the matrix into the intermembrane space, increasing the ___ __ gradient.

A

Cytochrome c

contains Fe3+/Fe2+, which is reduced to Fe2+ and oxidized to Fe3+.

generates energy from electron transfer to pump 4H+ from the matrix into the intermembrane space, increasing the hydrogen ion gradient.

52
Q

At complex IV,
four electrons from four cytochrome c are passed to other electron carriers.

electrons combine with hydrogen ions and oxygen (O2) to form two molecules of ___.

energy is used to pump H+ from the mitochondrial matrix into the intermembrane space, further increasing the hydrogen ion gradient

A

At complex IV,
four electrons from four cytochrome c are passed to other electron carriers.

electrons combine with hydrogen ions and oxygen (O2) to form two molecules of water.

energy is used to pump H+ from the mitochondrial matrix into the intermembrane space, further increasing the hydrogen ion gradient

53
Q

Energy is coupled with the production of ATP in a process called ____ _____.

A

Oxidative phosphorylation.

54
Q

oxidative phosphorylation, which:

links the energy from electron transport to a hydrogen ion gradient that drives the synthesis of ___.

allows complexes __, __, __ to act as hydrogen ion pumps, producing a hydrogen ion gradient.

equalizes __ and __ between the matrix and intermembrane space that occurs when H+ must return to the matrix.

A

ATP

I, II, IV

pH and electrical charge

55
Q

In the chemiosmotic model,

H+ cannot move through the inner membrane but returns to the matrix by passing through a fifth protein complex in the inner membrane called ___ ___ (also called complex V).

the flow of H+ from the intermembrane space through the ___ ___ generates energy that is used to synthesize ATP from ADP and Pi.

A

ATP Synthase

56
Q

When ____ enters electron transport at complex I, the energy transferred can be used to synthesize 2.5 ATP

A

NADH

57
Q

When ____ enters electron transport at complex II, it provides energy for the synthesis of 1.5 ATP

A

FADH2

58
Q

Electron transport
is regulated by the availability of ADP, Pi, ___, and NADH.

decreases with low levels of any of these compounds and decreases the formation of ___

A

Oxygen (O2)

ATP

59
Q

When a cell is active and ATP is consumed rapidly, the elevated levels of ___ will activate the synthesis of ATP.

The activity of electron transport is strongly dependent on the availability of ___ for ATP synthesis

A

ADP

60
Q

a mobile carrier between complexes II and III

A

Cyt C

61
Q

carries electrons from complexes I and II to complex III

A

CoQ

62
Q

accepts 2H+ and 2 electrons from FADH2

A

CoQ

63
Q

CO2, FADH2 and NADH are all products of?

A

Citric Acid Cycle

64
Q

NAD and H2O are all products of?

A

Electron Transport Chain

65
Q

The total ATP from complete oxidation of glucose is calculated by combining the ATP produced from

glycolysis (glucose produces seven ATPs):five ATPs from two ____ (malate–aspartate shuttle) and two ATPs from ___ ___ ___.

the oxidation of ____.

the citric acid cycle.

electron transport.

A

The total ATP from complete oxidation of glucose is calculated by combining the ATP produced from

glycolysis (glucose produces seven ATPs):five ATPs from two NADHs (malate–aspartate shuttle) and two ATPs from direct phosphate transfer.

the oxidation of pyruvate.

the citric acid cycle.
electron transport.

66
Q

In glycolysis, the oxidation of glucose stores energy in two ____ molecules and two ATP molecules from direct phosphate transfer.

A

NADH

67
Q

Because glycolysis occurs in the ____,

the NADH produced cannot pass through the mitochondrial inner membrane.

the hydrogen ions and electrons from NADH can be moved into and out of the mitochondria by a transporter, the ___-___ shuttle.

malate dehydrogenase catalyzes the reaction of oxaloacetate and NADH to yield ___ and ___.

a transporter binds the malate and carries it across the membrane into the matrix, where malate dehydrogenase oxidizes malate back to ____.

A

Because glycolysis occurs in the cytosol,

the NADH produced cannot pass through the mitochondrial inner membrane.

the hydrogen ions and electrons from NADH can be moved into and out of the mitochondria by a transporter, the malate–aspartate shuttle.

malate dehydrogenase catalyzes the reaction of oxaloacetate and NADH to yield malate and NAD+.

a transporter binds the malate and carries it across the membrane into the matrix, where malate dehydrogenase oxidizes malate back to oxaloacetate.

68
Q

The oxidation to oxaloacetate provides hydrogen ions and electrons that are used to reduce ___ to ____, which can now enter electron transport to synthesize ATP

A

The oxidation to oxaloacetate provides hydrogen ions and electrons that are used to reduce NAD+ to NADH, which can now enter electron transport to synthesize ATP

69
Q

Because the oxaloacetate produced in the matrix cannot cross the mitochondrial membrane, it

is converted back to _____;
moves out of the matrix back into the cytosol; and

undergoes transamination, which converts it to ____.

The resulting NAD+ can participate again in glycolysis in the cytosol.

A

Because the oxaloacetate produced in the matrix cannot cross the mitochondrial membrane, it

is converted back to aspartate;
moves out of the matrix back into the cytosol; and

undergoes transamination, which converts it to oxaloacetate.

The resulting NAD+ can participate again in glycolysis in the cytosol.

70
Q

Under ____ conditions, pyruvate

enters the mitochondria.

is ____ to give acetyl CoA, CO2, and NADH.

A

Under aerobic conditions, pyruvate

enters the mitochondria.

is oxidized to give acetyl CoA, CO2, and NADH.

71
Q

Because glucose yields two ____,

two NADHs enter electron transport.

their oxidation leads to the production of ___ ATPs.

A

Because glucose yields two pyruvates,

two NADHs enter electron transport.

their oxidation leads to the production of five ATPs.

72
Q

The two acetyl CoA produced from two pyruvates enter the citric acid cycle. Two acetyl CoA from one glucose produce a total of

NADHs;

FADH2s; and

ATPs.

A

The two acetyl CoA produced from two pyruvates enter the citric acid cycle. Two acetyl CoA from one glucose produce a total of

six NADHs;

two FADH2s; and

two ATPs.

73
Q

In electron transport, six NADHs produce __ ATPs, and two FADH2s produce __ ATPs.

A

In electron transport, six NADHs produce 15 ATPs, and two FADH2s produce 3 ATPs.

74
Q

In two turns of the citric acid cycle, a total of __ ATP molecules are produced.

A

20

75
Q

The complete oxidation of glucose to CO2 and H2O yields a maximum of __ ATPs.

A

32

76
Q

In a laboratory calorimeter, 1 mole of glucose produces ___ kcal.

A

690 kcal

77
Q

The remainder of the energy produced from glucose during the oxidation in our cells is lost as ___

A

Heat

Biochemistry Exam 4 (19 decks)

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