Deck 19: Harvesting Electrons From the Cycle

Question 1

Carbons from carbohydrates enter the citric acid cycle in the form of _______________.

Answer 1

acetyl CoA

Question 2

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
The product of the complete oxidation of carbon in the citric acid cycle is ____________.

Answer 2

k

Question 3

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
The function of the citric acid cycle is to ____________ high-energy electrons.

Answer 3

d

Question 4

During the oxidation of isocitrate, the intermediate that is decarboxylated to form α-ketoglutarate is _______________.

Question 5

______________ reactions are the process of filling up a cycle with outside carbon compounds.

Question 6

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
____________: The name applied to metabolic reactions that replenish the citric acid cycle intermediates that are depleted because they were used for biosynthesis.

Question 7

In the citric acid cycle, the _______________ is produced by a substrate-level phosphorylation.

Question 8

The free energy at standard state for MDH in the direction of the citric acid cycle is _______________.

Question 9

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
The substance ____________ is a competitive inhibitor of succinate dehydrogenase.

Question 10

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
The intermediate between citrate and isocitrate is ____________.

Question 11

_______________ are organelles in plants and some bacteria where two-carbon acetyl units are converted into four-carbon units (succinate) for glucose synthesis, energy production, and biosynthesis.

Question 12

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
____________: A name suggested for associated multienzyme complexes in metabolism.

Question 13

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
Succinate dehydrogenase is located in the ____________.

Question 14

Organisms that can convert fat into sugar use the _______________ cycle .

Question 15

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
____________: The product found by the condensation of oxaloacetate and acetyl CoA.

Question 16

_______________ is a citric acid cycle enzyme that is also an example of an iron-sulfur protein.

Question 17

In general, the citric acid cycle is inhibited under _____________ (high, low) energy conditions.

Question 18

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
____________ is the primary control point of the citric acid cycle.

Question 19

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) cytosol
b) isocitrate dehydrogenase
c) anaplerotic
d) harvest
e) cis-aconitate
f) melonate
g) metabolon
h) oxaloacetate
i) inner membrane
j) citrate
k) carbon dioxide
l) glyoxylate cycle
m) malate dehydrogenase
____________: This citric acid cycle intermediate is at both the beginning and the end of the citric acid cycle.

Question 20

_______________ is the first citric acid cycle intermediate to be oxidized.

Question 21

The direct channeling of proteins from one enzyme to the next will happen in a(n):

A) protein complex.
B) metabolon.
C) linker coenzyme.
D) cell with sufficient available water.
E) electron acceptor.

Question 22

What molecule initiates the citric acid cycle by reacting with oxaloacetate?

A) pyruvate
B) acetyl CoA
C) oxaloacetate
D) All of the above.
E) None of the above.

Question 23

Succinate dehydrogenase deficiency or genetic mutation results in:

A) cancer through HIF-1.
B) decreased rate of gylcolysis.
C) depletion of succinate in mitochondria.
D) A and B.
E) A, B, and C.

Question 24

In which step of the citric acid cycle is FADH2 formed?

A) the conversion of succinate to malate
B) the conversion of succinate to oxaloacetate
C) the conversion of succinate to fumarate
D) the conversion of malate to oxaloacetate
E) None of the above.

Question 25

What reaction serves to link glycolysis and the citric acid cycle?

Question 26

Isomerization of citrate is catalyzed by:

A) citrate synthase.
B) aldolase.
C) ɑ-ketogutarate dehydrogenase.
D) Aconitase.
E) Citrate isomerase

Question 27

Which of these compounds is oxidized by a multienzyme complex that requires five different coenzymes?

A)
B)
C)
D)
E)

Question 28

Which of the following vitamins are precursors to coenzymes that are necessary for the formation of succinyl CoA from α-ketoglutarate?

A) thiamine, riboflavin, niacin, lipoic acid, and pantothenic acid
B) thiamine, riboflavin, niacin, lipoic acid, pantothenic acid, and biotin
C) thiamine, riboflavin, niacin, and biotin
D) thiamine, riboflavin, and lipoic acid
E) None of the above.

Question 29

List the five coenzymes that are required for the oxidative decarboxylation of α-ketoglutarate and give the essential nutrient (vitamin) that is required for each.

Question 30

The glyoxylate cycle enables plants to survive using only:

A) pyruvate.
B) acetate.
C) oxaloacetate.
D) All of the above.
E) None of the above.

Question 31

In muscle, the enzyme used to catalyze a substrate-level phosphorylation is:

A) nucleoside triphosphate transferase.
B) protein kinase C.
C) GTP kinase.
D) succinyl CoA synthetase.
E) ATP-GTP transferase.

Question 32

A mutation in the active site of succinyl CoA synthetase where His is converted to a lysine would result in which?

A) increased stable folding
B) the loss of a succinyl phosphate intermediate
C) the loss of a positive-charged amino acid necessary for catalysis
D) All of the above
E) None of the above

Question 33

What is/are the chemical change(s) involved in the conversion of citrate into isocitrate?

A) hydration followed by dehydration
B) oxidation
C) oxidation followed by reduction
D) dehydration followed by hydration
E) A and B

Question 34

In addition to pyruvate dehydrogenase, what other enzymes are key regulatory sites in the citric acid cycle?

A) isocitrate dehydrogenase
B) ɑ-ketoglutarate dehydrogenase
C) citrate synthase (in bacteria)
D) A and B
E) A, B, and C

Question 35

Why is the isomerization of citrate to isocitrate a necessary step of the citric acid cycle?

Question 36

Formation of citrate from acetyl CoA and oxaloacetate is a(n) _________ reaction.

A) oxidation
B) reduction
C) condensation
D) ligation
E) None of the above.

Question 37

In which reaction is ATP directly formed in the citric acid cycle?

A) conversion of succinyl CoA to succinate
B) decarboxylation of ɑ-ketoglutarate
C) conversion of isocitrate to ɑ-ketoglutarate
D) All of the above.
E) None of the above.

Question 38

Explain when GDP is used as a substrate with succinyl CoA synthetase, and when ADP is.

Question 39

Approximately how many ATP or GTP equivalents are produced during one turn of the citric acid cycle?

A) 10
B) 6
C) 9
D) 12
E) None of the above.

Question 40

Draw each reaction and the name of the enzyme for the production of CO2 from pyruvate.

Question 41

What is the energy source that drives the condensation of oxaloacetate and and acetyl CoA to produce citrate?

Question 42

Are the acetyl carbons that enter the citric acid cycle the exact same carbons that leave as CO2? Briefly explain.

Question 43

In what organisms and by what mechanism can carbon from fat be converted to sugar?

Question 44

How is succinate dehydrogenase unique when compared to the other enzymes in the citric acid cycle?

Question 45

How does the decarboxylation of ɑ-ketoglutatarate resemble that of pyruvate decarboxylation?

Question 46

How many ATP equivalents are produced from the total oxidation of 1 pyruvate to 3 CO2?

Question 47

Give an explanation about why the oxidation of isocitrate is so exergonic.

Question 48

In the α-ketoglutarate dehydrogenase enzyme complex, why is the observed electron transfer from FADH2 to NAD+ unusual?