Chapter 24. Chapter 24

Problem-Solving Video Assessment

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Chapter 24 Problem-Solving Video Assessment

1.

Put the following steps involved in the formation of heme from atmospheric N₂ in chronological order. Which step is the fourth step in the process?

The nitrogen atom in glycine becomes incorporated in porphobilinogen via the formation and subsequent condensation of two δ-aminolevulinate molecules.

NH₄⁺ from nitrogen fixation is incorporated into glutamate.

Serine is formed in a three-step pathway involving glutamate and 3-phosphoglycerate.

Cyclization and modification of porphobilinogen results in the formation of protoporphyrin IX.

One carbon unit is transferred from serine to tetrahydrofolate.

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

2.

Which of the following statements concerning the formation of heme from atmospheric N₂ is correct?

Tetrahydrofolate is used as a carrier of two carbon units.

The fixation of atmospheric nitrogen into ammonia is a spontaneous, energetically favorable reaction.

Some nitrogen is lost as ammonium during the conversion of porphobilinogen to tetrapyrrole.

The formation of glutamate from ammonia involves the formation of α-ketoglutarate as a reaction product.

The δ-aminolevulinate intermediate is formed from the condensation of serine and succinyl-CoA.

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

3.

A mutation in the α-ketoglutarate dehydrogenase gene will most strongly affect the formation of which N₂-to-heme intermediate?

ammonia

δ-aminolevulinate

glutamate

glycine

serine

_feedback_correct: Correct. _feedback_incorrect: Incorrect.

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Chapter 24. Chapter 24

Introduction

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