Chapter 30. Problem 30.2

Problem-Solving Video Assessment

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Problem 30.2: A Versatile Building Block

1.

Imagine that eight aspartate molecules are deaminated and enter gluconeogenesis. What is the net gain in glucose molecules?

0.5 molecule

2 molecules

4 molecules

8 molecules

16 molecules

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

2.

Which statement describes how the NADH cofactor is used during the conversion of aspartate into glucose?

It accepts an amino group from aspartate before transferring it to α-ketoglutarate.

It donates electrons to 1,3-bisphosphoglycerate to form glyceraldehyde 3-phosphate.

It accepts electrons from malate thereby forming oxaloaceatate.

It donates electrons to phosphoenolpyruvate to form 2-phosphoglycerate.

It accepts electrons from glyceraldehyde 3-phosphate in the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase.

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

3.

Put the following steps involved in the formation of oxaloacetate from aspartate via the urea cycle in chronological order. Which step is the third step in the process?

Malate is formed via the action of fumerase enzyme, followed by oxidation to form oxaloacetate.

Argininosuccinate is formed from aspartate and the citrulline intermediate.

Bicarbonate ion and ammonia formed from the breakdown of amino acids condense to form carbamoyl phosphate.

Urea forms following the hydration of arginine and is removed from cells as a waste product.

Fumarate and arginine are formed as products of argininosuccinase activity.

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

4.

Imagine a urea cycle in which the argininosuccinate synthetase enzyme is non-functional. Which intermediate during the conversion from aspartate to oxaloacetate would accumulate to the highest level?

citrulline

carbamoyl phosphate

fumarate

argininosuccinate

malate

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

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Chapter 30. Problem 30.2

Introduction

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