Deck 26: The Pentose Phosphate Pathway

Question 1

_________________ is the enzynme that catalyzes the hydrolysis of the ester linkage of the lactone, resulting in the ring opening.

Answer 1

lactonase

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) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
_________________ is the committed step of the pentose phosphate pathway.

Answer 2

glucose 6-phosphate dehydrogenase

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) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
The prosthetic group ____________ is tightly bound to the enzyme transketolase.

Answer 3

f

Question 4

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
____________ results in a C3 and a C7 carbohydrate from two C5 carbohydrate precursors.

Question 5

The currency of reducing power is:

A) NADPH.
B) NADH.
C) AMP.
D) ADP.
E) None of the above.

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) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
____________ is the key source of biosynthetic reducing equivalents.

Question 7

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
Two molecules of ____________ are formed in phase II of the pentose phosphate pathway.

Question 8

The enzyme transketolase transfers a _________________-carbon fragment from a ketose to an aldose.

Question 9

The oxidative phase of the pentose phosphate pathway produces _________________, which is required for lipid biosynthesis.

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) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
____________ is a substrate for the pentose phosphate pathway.

Question 11

_________________ is converted to xylulose 5-phosphate by the enzyme phosphopentose epimerase.

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) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
Ribulose 5-phosphate is the result of the ____________ phase.

Question 13

The manifestation of the disease is actually caused by a defect in _________________.

Question 14

NADPH is required by the liver and adipose for synthesis of _________________.

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) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
Excess carbons of the pentose phosphate pathway are shunted to what other metabolic pathway?

Question 16

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
This is due to a loss in activity in which enzyme in red blood cells?

Question 17

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
The second phase of the pentose phosphate pathway is the ____________ phase.

Question 18

Hemolytic anemia is caused by a deficiency of the enzyme _________________.

Question 19

Isomers with multiple asymmetric centers differing in only one asymmetric center is/are a(n) _________________.

Question 20

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) nonoxidative
b) oxidative
c) transketolase
d) glucose 6-phosphate
e) reducing equivalents
f) thiamine pyrophosphate
g) transaldolase
h) glutathione reductase
i) glycolysis
j) NADH
k) fructose 6-phosphate
l) NADPH/pentose phosphate pathway
m) glucose
____________ and transketolase are the enzymes that link glycolysis and the pentose phosphate pathway.

Question 21

NADPH is required for which of the following detoxification reactions or enzymes?

A) cytochrome P450 monooxygenase
B) reduction of glutathione(ox)
C) deamination of serine
D) A and B
E) All of the above.

Question 22

What is the common feature of the mechanism of the metabolic oxidations of 6-phosphogluconate and isocitrate?

Question 23

What is a primary difference between the oxidation of glucose to CO2 by glycolysis and the citric acid cycle versus the oxidation via the pentose phosphate pathway?

Question 24

Reduced glutathione maintains red blood cell structure by:

A) protecting against falciparum malaria.
B) maintaining hemoglobin structure.
C) preventing Heinz body formation.
D) A and C.
E) B and C.

Question 25

Which enzyme controls the pentose phosphate pathway?

Question 26

In the nonoxidative stage of the pentose phosphate pathway, intermediates of _____________ are produced.

A) the citric acid cycle
B) glycolysis
C) glycogen degradation
D) A and C
E) B and C

Question 27

The pentose phosphate pathway:

A) is stimulated by NADH.
B) is stimulated by NADPH.
C) operates primarily in nondividing cells.
D) is contained within the mitochondria of adipose cells.
E) None of the above.

Question 28

In mode two:

A) the needs for NADPH and ribose 5-phosphate are balanced,
B) much more NADPH than ribose 5-phosphate is required.
C) more ribose 5-phosphate than NADPH is required.
D) NADPH and CO2 are required.
E) excess NAD+is required. .

Question 29

What is the net reaction of the transketolase and transaldolase steps?

A)
$3 \mathrm { C } _ { 5 } \rightleftharpoons 2 \mathrm { C } _ { 6 } + \mathrm { C } _ { 3 }$
B)
$2 \mathrm { C } _ { 5 } \rightleftharpoons \mathrm { C } _ { 6 } + \mathrm { C } _ { 4 }$
C)
$3 \mathrm { C } _ { 5 } \rightleftharpoons \mathrm { C } _ { 6 } + 3 \mathrm { C } _ { 3 }$
D)
$2 \mathrm { C } _ { 5 } \rightleftharpoons 2 \mathrm { C } _ { 4 } + \mathrm { C } _ { 2 }$
E) None of the above.

Question 30

How can a deficiency of glucose 6-phosphate confer a physiological advantage?

Question 31

Which of the following reactions is not part of the pentose phosphate pathway?

A)
$\mathrm { C } _ { 5 } + \mathrm { C } _ { 5 } \stackrel { \text { Transketolase } } { ? } \mathrm { C } _ { 3 } + \mathrm { C } _ { 7 }$
B)
$\mathrm { C } _ { 4 } + \mathrm { C } _ { 5 } \stackrel { \text { Transketolase } } {? } \mathrm { C } _ { 3 } + \mathrm { C } _ { 6 }$
C)
$\mathrm { C } _ { 3 } + \mathrm { C } _ { 7 }\stackrel { \text { Transketolase } } {? } \mathrm { C } _ { 6 } + \mathrm { C } _ { 4 }$
D)
$\mathrm { C } _ { 5 } + \mathrm { C } _ { 6 } \stackrel { \text { Transketolase } } {? } \mathrm { C } _ { 2 } + \mathrm { C } _ { 9 }$

E) All of the above.

Question 32

How is this maintained?

Question 33

Which biosynthetic pathway requires NADH?

A) cholesterol
B) fatty acid
C) nucleotide
D) All of the above.
E) None of the above.

Question 34

What are the substrates and products of these reactions?

Question 35

Under what conditions might the pentose phosphate pathway produce large amounts of NADPH without significant net production of ribose 5-phosphate?

A) synthesis of fatty acids in the liver
B) when pyruvate is synthesized to generate ATP
C) when cells are rapidly dividing
D) A and C
E) B and C

Question 36

How is the pentose phosphate pathway regulated?

Question 37

______________ oxidizes the C3 hydroxyl to a ketone.

A) Lactonase
B) Glucose 6-phosphate dehydrogenase
C) Transaldolase
D) Transketolase
E) 6-phosphogluconate dehydrogenase

Question 38

Glucose 6-phosphate dehydrogenase is inhibited by low levels of:

A) NADPH.
B) NADP+.
C) ribose 5-phosphate.
D) A and C.
E) B and C.

Question 39

Which sugar(s) is/are converted into ribulose 5-phosphate by a single enzymatic step?

A) ribose 5-phosphate
B) xyulose 5-phosphate
C) erythrose 4-phosphate
D) A and B
E) C and C

Question 40

The purpose of the pentose phosphate pathway is to:

A) generate ATP.
B) generate NADPH.
C) synthesize five-carbon sugars.
D) A and B.
E) B and C.

Question 41

How does NADPH protect red blood cells from hemolysis?

Question 42

What are the reactions in the oxidative phase of the pentose phosphate pathway?