Question 1

Which enzyme uses cellular NADPH to regenerate reduced glutathione?

Accepted Answer

Glutathione reductase is the enzyme that uses cellular NADPH to regenerate reduced glutathione.

Question 2

Which enzyme in the pentose phosphate pathway catalyzes the following reaction?

Accepted Answer

6-phosphogluconate dehydrogenase catalyzes the conversion of 6-phosphogluconate to ribulose-5-phosphate in the oxidative phase of the pentose phosphate pathway.

Question 3

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

Accepted Answer

Sedoheptulose-7-phosphate is a molecule found in the nonoxidative phase of the pentose phosphate pathway. Glucose-6-phosphate is found in the oxidative phase, and phosphoenolpyruvate is not involved in the pentose phosphate pathway. Additionally, the molecule listed as D is not a valid compound.

Question 4

If the ratio of NADP⁺to NADPH were high, the

Accepted Answer

A high ratio of NADP⁺ to NADPH indicates a need for more NADPH. This activates the oxidative phase of the pentose phosphate pathway, which generates NADPH. Therefore, choice B is the correct answer.

Question 5

What molecule activates the pentose phosphate pathway?

Accepted Answer

The answer of What molecule activates the pentose phosphate pathway?
...

Question 6

The pentose phosphate pathway occurs in the

Accepted Answer

The pentose phosphate pathway (also known as the phosphogluconate pathway or hexose monophosphate shunt) occurs in the cytoplasm of cells. It is an alternative pathway to glycolysis for the metabolism of glucose, producing pentoses (such as ribose) for nucleotide synthesis, reducing power in the form of NADPH, and intermediates for the synthesis of other important biomolecules.

Question 7

The products of the oxidative portion of the pentose phosphate pathway are carbon dioxide and

Accepted Answer

The oxidative phase of the pentose phosphate pathway generates 2 molecules of NADPH and 1 molecule of ribulose-5-phosphate, a pentose phosphate, along with carbon dioxide.

Question 8

Starting from the oxidative phase of the pentose phosphate pathway, how many ATP and high-energy reduced molecules, respectively, are made in going from one glucose molecule to glyceraldehyde-3-phosphate and fructose-6-phosphate?

Accepted Answer

In the oxidative phase of pentose phosphate pathway, no ATP or high-energy reduced molecules are produced. Therefore, the answer cannot be option C or D. In the non-oxidative phase, glyceraldehyde-3-phosphate and fructose-6-phosphate are produced from the intermediates of the pathway, but no net production of ATP or high-energy reduced molecules occurs. However, two high-energy reduced molecules (NADPH) are produced in the oxidative phase, which can be used in other metabolic pathways. Therefore, the answer is B.

Question 9

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

Accepted Answer

Fructose-6-phosphate is involved in the nonoxidative phase of the pentose phosphate pathway, while ATP and NADPH are products of this pathway. The option D appears to be an invalid or irrelevant molecule.

Question 10

Which of the following is NOT a role played by the pentose phosphate pathway?

Accepted Answer

The pentose phosphate pathway does not directly convert pyruvate into TCA cycle intermediates. It is primarily involved in generating NADPH for other metabolic pathways and producing 5-carbon ribose sugars for nucleotide synthesis. It can also convert sugars in the DNA backbone into glycolysis intermediates.

Question 11

The pentose phosphate pathway

Accepted Answer

The pentose phosphate pathway allows 5C sugars (pentoses) to converge with or diverge from the glycolysis pathway. It is a parallel pathway to glycolysis and does not directly produce ATP. While it does involve the oxidation of glucose, it does not couple the loss of CO2 with the formation of NADH like the TCA cycle. It also contains a variety of sugar molecules of different lengths, not just 5C.

Question 12

Which of the following metabolites is NOT a gluconeogenesis substrate in humans?

Accepted Answer

Acetate is not a gluconeogenesis substrate in humans. While pyruvate, lactate, and oxaloacetate can all be converted into glucose through gluconeogenesis, acetate cannot be directly used as a substrate for glucose synthesis.

Question 13

Which is the substrate or product of the reactions that comprise the oxidative branch of the pentose phosphate pathway?

Accepted Answer

The answer of Which is the substrate or product of...

Question 14

How would individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress?

Accepted Answer

Glucose-6-phosphate dehydrogenase is an important enzyme in the pentose phosphate pathway, which generates NADPH and ribose-5-phosphate. NADPH is an essential cofactor in the regeneration of reduced glutathione, an important antioxidant. Individuals with decreased levels of glucose-6-phosphate dehydrogenase would have reduced NADPH production, leading to decreased ability to regenerate reduced glutathione and respond to oxidative stress.

Question 15

The main function of the pentose phosphate pathway is to provide

Accepted Answer

The pentose phosphate pathway primarily functions to provide the cell with ribose for nucleotide synthesis and NADPH for reductive biosynthesis and antioxidant defense. While the pathway can also generate some ATP, this is not its primary function. Option A is not entirely accurate since the pentose phosphate pathway can also be inhibited, and option C is incorrect as excess amino acids are primarily metabolized through other pathways.

Question 16

Which enzyme class catalyzes the following pentose phosphate pathway reaction?

Accepted Answer

The answer of Which enzyme class catalyzes the following pentose...

Question 17

The pentose phosphate pathway

Accepted Answer

The pentose phosphate pathway is linked at its start and at its end to the glycolysis pathway, but it does not converge glycolysis intermediates with TCA cycle intermediates. Seduheptulose-7-phosphate is not directly produced by the pentose phosphate pathway. The pathway occurs in the cytoplasm, not the mitochondrial matrix.

Question 18

What enzyme class in the nonoxidative phase of the pentose phosphate pathway allows for the reaction of ribose-5-phosphate and xylulose-5-phosphate to produce glyceraldehyde-3-phosphate and seduheptulose-7-phosphate?

Accepted Answer

Transferases are enzymes that catalyze the transfer of a functional group, such as a phosphate group, from one molecule to another. In this case, the transferase enzyme allows for the transfer of a phosphate group from ribose-5-phosphate to xylulose-5-phosphate, producing glyceraldehyde-3-phosphate and seduheptulose-7-phosphate. The other enzyme classes listed (isomerase, hydrolase, and oxidoreductase) do not fit the reaction described in the question.

Question 19

Which enzyme class catalyzes the following pentose phosphate pathway reaction (note that there may be some missing reactants and products)?

Accepted Answer

The answer of Which enzyme class catalyzes the following pentose...

Question 20

Which enzyme in the pentose phosphate pathway is regulated to control flux through the pathway?

Accepted Answer

Glucose-6-phosphate dehydrogenase is the regulatory enzyme in the pentose phosphate pathway. It is the rate-limiting enzyme and is allosterically activated by NADP+ and inhibited by NADPH.

Quiz 14: Carbohydrate Metabolism

Which enzyme uses cellular NADPH to regenerate reduced glutathione?

Which enzyme in the pentose phosphate pathway catalyzes the following reaction?

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

If the ratio of NADP⁺to NADPH were high, the

What molecule activates the pentose phosphate pathway?

The pentose phosphate pathway occurs in the

The products of the oxidative portion of the pentose phosphate pathway are carbon dioxide and

Starting from the oxidative phase of the pentose phosphate pathway, how many ATP and high-energy reduced molecules, respectively, are made in going from one glucose molecule to glyceraldehyde-3-phosphate and fructose-6-phosphate?

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

Which of the following is NOT a role played by the pentose phosphate pathway?

The pentose phosphate pathway

Which of the following metabolites is NOT a gluconeogenesis substrate in humans?

Which is the substrate or product of the reactions that comprise the oxidative branch of the pentose phosphate pathway?

How would individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress?

The main function of the pentose phosphate pathway is to provide

Which enzyme class catalyzes the following pentose phosphate pathway reaction?

The pentose phosphate pathway

What enzyme class in the nonoxidative phase of the pentose phosphate pathway allows for the reaction of ribose-5-phosphate and xylulose-5-phosphate to produce glyceraldehyde-3-phosphate and seduheptulose-7-phosphate?

Which enzyme class catalyzes the following pentose phosphate pathway reaction (note that there may be some missing reactants and products) ?

Which enzyme in the pentose phosphate pathway is regulated to control flux through the pathway?

Quiz 14: Carbohydrate Metabolism

Which enzyme uses cellular NADPH to regenerate reduced glutathione?

Which enzyme in the pentose phosphate pathway catalyzes the following reaction?

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

If the ratio of NADP+ to NADPH were high, the

What molecule activates the pentose phosphate pathway?

The pentose phosphate pathway occurs in the

The products of the oxidative portion of the pentose phosphate pathway are carbon dioxide and

Starting from the oxidative phase of the pentose phosphate pathway, how many ATP and high-energy reduced molecules, respectively, are made in going from one glucose molecule to glyceraldehyde-3-phosphate and fructose-6-phosphate?

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

Which of the following is NOT a role played by the pentose phosphate pathway?

The pentose phosphate pathway

Which of the following metabolites is NOT a gluconeogenesis substrate in humans?

Which is the substrate or product of the reactions that comprise the oxidative branch of the pentose phosphate pathway?

How would individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress?

The main function of the pentose phosphate pathway is to provide

Which enzyme class catalyzes the following pentose phosphate pathway reaction?

The pentose phosphate pathway

What enzyme class in the nonoxidative phase of the pentose phosphate pathway allows for the reaction of ribose-5-phosphate and xylulose-5-phosphate to produce glyceraldehyde-3-phosphate and seduheptulose-7-phosphate?

Which enzyme class catalyzes the following pentose phosphate pathway reaction (note that there may be some missing reactants and products) ?

Which enzyme in the pentose phosphate pathway is regulated to control flux through the pathway?

If the ratio of NADP⁺to NADPH were high, the