Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochem Pathways > Energy Metabolism > Flashcards

Energy Metabolism Flashcards

1
Q

Which of the following is not involved in the pyruvate dehydrogenase reaction?

(a) Coenzyme A
(b) Lipoic acid
(c) NAD+
(d) Biotin
(e) Thiamine pyrophosphate

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which of the following will happen to pyruvate when oxygen is present and the cell needs to produce ATP?

(a) Pyruvate will be converted to lactate.
(b) Pyruvate will be converted back to glucose via gluconeogenesis.
(c) Pyruvate will be oxidised via pyruvate dehydrogenase and the TCA cycle.
(d) Pyruvate will be converted to fat via acetyl CoA.
(e) All of the above

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In a eukaryotic cell, most of the enzymes of the TCA cycle are located in the

(a) mitochondrial matrix.
(b) inner mitochondrial membrane.
(c) intermembrane space.
(d) outer mitochondrial membrane.
(e) cytosol.

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which enzyme does not catalyse a reaction that releases carbon dioxide?

(a) α-ketoglutarate dehydrogenase complex
(b) pyruvate dehydrogenase
(c) malate dehydrogenase
(d) isocitrate dehydrogenase
(e) pyruvate carboxylase

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

he reaction sequence from succinate to oxaloacetate and involving hydrogen and water is:

(a) addition, elimination, addition
(b) addition, condensation, elimination
(c) condensation, addition, elimination
(d) elimination, addition, elimination
(e) elimination, addition, condensation

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The TCA cycle is regulated by:

(a) the availability of acetyl CoA from the pyruvate dehydrogenase reaction.
(b) allosteric effects of ATP and AMP on isocitrate dehydrogenase.
(c) allosteric effects of acetyl CoA on citrate synthase.
(d) feedback inhibition by ATP on the electron transport chain.
(e) none of the above.

A

B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which of the following statements about the chemiosmotic theory is correct?

(a) Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.
(b) It predicts that oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrane.
(c) The effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes.
(d) The membrane ATP synthase has no significant role in the chemiosmotic theory.
(e) All of the above are correct

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Oxidative phosphorylation requires all the items listed below except:

(a) ATP synthase in the correct position in the membrane.
(b) enzyme complexes embedded in a membrane.
(c) the flow of electrons from NADH and QH2 in the membrane.
(d) a matrix more positively charged than the intermembrane space.
(e) a terminal electron acceptor which is O 2 in mitochondria.

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

ATP synthase is located in the _____ of the mitochondrion.

(a) outer membrane
(b) inner membrane
(c) matrix
(d) intermembrane space
(e) cristae space

A

B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which of the following is(are) TRUE concerning the metabolic reaction shown below?

Pyruvate + NAD+ + CoA-SH -> Acetyl-CoA + NADH + H+ + CO2

I. The enzyme that catalyses this reaction contains a pyridoxal phosphate prosthetic group.
II. This reaction is an oxidative decarboxylation.
III. The enzyme that catalyses this metabolic conversion is activated by high concentrations of ATP.

(a) I, II, III
(b) II, III
(c) II only
(d) III only
(e) I, II

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The final product of oxidative phosphorylation is _____
(a) O2
(b) ADP
(c) NADPH
(d) ATP
(e) FMNH2

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

After passing through the TCA cycle, one mole of pyruvate will result in the formation of _____ moles of carbon dioxide and _____ mole(s) of ATP (or GTP).

(a) 2; 2
(b) 2; 1
(c) 3; 2
(d) 3; 1
(e) 6; 2

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

About how many total ATP equivalents are generated by the complete oxidation of one molecule of acetyl CoA?

(a) 1.5
(b) 2.5
(c) 3
(d) 10
(e) 30

A

D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which of the following pairs of statements is mismatched?

(a) outer mitochondrial membrane – permeable to ions and water
(b) inner mitochondrial membrane – permeable to O2 and CO2
(c) outer mitochondrial membrane – folded into cristae
(d) inner mitochondrial membrane – location of ATP synthase
(e) mitochondrial matrix – ATP synthase F1 subunits extend here

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The reaction catalysed by pyruvate carboxylase is an example of a(n) _____ reaction because it replenishes TCA cycle intermediates that have been siphoned off for use in other reactions.

(a) amphibolic
(b) amphipathic
(c) anaplerotic
(d) cataplerotic
(e) hypermetabolic

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many NADH molecules are produced when one acetyl group is oxidized in the TCA cycle?

(a) 1
(b) 2
(c) 3
(d) 4
(e) more than 4

A

C

17
Q

The chemiosmotic theory explains

(a) the phosphorylation of ADP.
(b) the electron transport chain.
(c) the differences between inner and outer mitochondrial membranes.
(d) the source of energy for formation of mitochondrial ATP.
(e) aerobic respiration

A

D

18
Q

Electrons from FADH2 are delivered to _____ and electrons from NADH are delivered to _____ of the electron transport chain.

(a) Complex I; Complex II
(b) Complex I; Complex III
(c) Complex II; Complex III
(d) Complex II; Complex I
(e) Complex I; Complex IV

A

D

19
Q

The protonmotive force is a result of ______

(a) the flow of electrons from the matrix to the inner membrane space
(b) a combination of an electrical potential and a chemical potential
(c) the flow of protons within the inner mitochondrial membrane
(d) energy from electron transfer being stored as a stable high potential intermediate
(e) all the above are correct

A

B

20
Q

Which of the following statements is(are) TRUE about oxidative phosphorylation?

I. Electron transport provides energy to pump protons into the intermembrane space.
II. An electrochemical gradient is formed across the inner mitochondrial membrane.
III. Potassium and sodium ions form an ionic gradient across the inner mitochondrial membrane.
IV. Complexes I, III, and IV actively transport protons into the intermembrane space during electron transport.

(a) I, II, III, IV
(b) I, II, IV
(c) II, III, IV
(d) I, IV
(e) II, IV

A

B

21
Q

Write down the three reactions in the tricarboxylic acid (TCA) cycle in which NADH is produced.
The TCA cycle is frequently described as the major pathway of aerobic catabolism, which means that it is an oxygen-dependent degradative process. However, none of the reactions of the cycle directly involves oxygen as a reactant. Why is the pathway oxygen-dependent?

A

NADH is produced in the reactions catalysed by isocitrate dehydrogenase, the α-ketoglutarate dehydrogenase complex, and malate dehydrogenase.

These reactions in the TCA cycle are indirectly dependent on the presence of O 2 because the NADH produced in the reactions is normally recycled to NAD+ by passage of electrons from NADH through the respiratory chain to O 2. With no O 2 to accept electrons from NADH, the accumulation of NADH effectively stops the TCA cycle

22
Q

Write the balanced biochemical equations for the metabolism of:

  • 1 molecule of glucose by glycolysis,
  • 2 molecules of pyruvate by the pyruvate dehydrogenase linking reaction
  • 2 molecules of acetyl CoA by the tricarboxylic acid (TCA) cycle, including all cofactors.
  • What is the overall net biochemical equation for the combination of these 3 reactions (glycolysis + PDH reaction + TCA cycle)?
A

Glycolysis:
Glucose + 2 ADP + 2 Pi + 2 NAD+ -> 2 pyruvate + 2 ATP + 2 NADH

Pyruvate dehydrogenase:
2 Pyruvate + 2 NAD+ + 2 CoA -> 2 acetyl CoA + 2 CO 2 + 2 NADH

TCA cycle:
2 Acetyl CoA + 2 FAD + 6 NAD+ + 2 ADP + 2 Pi -> 2 CoA + 2 FADH2 + 6 NADH + 2 ATP + 4 CO2
NB: TCA cycle produces GTP that is equiv. to ATP

Overall net equation:
Glucose + 4 ADP + 4 Pi + 10 NAD+ + 2 FAD -> 6 CO 2 + 4 ATP + 10 NADH + 2 FADH2

23
Q

The TCA cycle begins with the condensation of acetyl CoA with
oxaloacetate. Describe three possible sources for the acetyl CoA

A

Acetyl CoA is produced by:
(1) the pyruvate dehydrogenase complex,
(2) β oxidation of fatty acids, or
(3) degradation of certain amino acids

24
Q

Describe, in simple diagrams and a few words, the chemiosmotic theory for coupling oxidation to phosphorylation in mitochondria

A

There are three central elements in the chemiosmotic model:
(1) Electron flow through asymmetrically arranged membrane-bound carriers causes transmembrane flow of H+ , creating a proton gradient (a proton motive force).
(2) The proton motive force drives protons back across the membrane via specific proton channels (composed of Fo).
(3) The energy released by “downhill” movement of protons is captured when ADP and Pi are condensed by ATP synthase (FoF1).

25
Q

Consider a liver cell carrying out the oxidation of glucose under aerobic conditions. Suppose that we added a very potent and specific inhibitor of the mitochondrial ATP synthase, completely inhibiting this enzyme. Indicate whether each of the following statements about the effect of this inhibitor is true or false; if false, explain in a sentence or two why it is false.

(a) ATP production in the cell will quickly drop to zero.
(b) The rate of glucose consumption by this cell will decrease sharply.
(c) The rate of oxygen consumption will increase.
(d) The TCA cycle will speed up to compensate.
(e) The cell will switch to fatty acid oxidation as an alternative to glucose oxidation, and the inhibitor will therefore have no effect on ATP production

A

(a) False. Mitochondrial ATP synthesis will cease, but to compensate, cells will accelerate the production of ATP by glycolysis, preventing ATP levels from dropping to zero.

(b) False. The acceleration of glycolysis noted above will actually increase the rate of glucose consumption.

(c) False. Because electron transfer through the respiratory chain is tightly coupled to ATP synthesis, blocking ATP synthase blocks electron flow and oxygen consumption.

(d) False. The TCA cycle is an oxidative pathway, producing NADH. When electron flow from NADH to O is blocked, NADH accumulates, NAD+ is depleted, and the TCA cycle slows for lack of an electron acceptor (NAD+ ).

(e) False. Oxidation of fats produces NADH, FADH2, and acetyl-CoA, which is further oxidized via the TCA cycle. For the reasons noted above, blocking electron flow through the respiratory chain prevents ATP synthesis with energy from fatty acid oxidation.

26
Q

Match the following metabolic states or processes with the correct subcellular locations, in which they exist or occur:

Phosphorylation of ADP by ATP synthase
Elevated proton concentration that drive ATP synthesis
Breakdown of acetyl CoA to CO2
Synthesis of pyruvate

Cytosol
Mitochondria Matrix
Intermembrane space of mitochondria
Inner membrane of mitochondria

A

Phosphorylation of ADP by ATP synthase - inner membrane of mitochondria

Elevated proton concentration that drive ATP synthesis - intermembrane space of mitochondria

Breakdown of acetyl CoA to CO2 - mitochondrial matrix

Synthesis of pyruvate - cytosol

Biochem Pathways (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions