Question 1

ALT (SGPT) and AST (SGOT) are serum transaminase enzymes that are easy to measure and greatly increase when there is damage to which organ?

Accepted Answer

Liver

Question 2

CK (creatine kinase) is a serum kinase enzyme that is easy to measure and greatly increases when there is damage to which tissue?

Accepted Answer

Heart

Question 3

Urea synthesis in mammals takes place mainly in which organ?

Accepted Answer

Liver

Question 4

Tetrahydrofolate acts as a methyl/one-carbon shuttle ______ between different substrates.

Accepted Answer

Between various biomolecules

Question 5

Most amino acid degradation pathways lead to:

Accepted Answer

Citric acid cycle intermediates

Question 6

Which of the following equations best represents the transamination reaction catalyzed by ALT (alanine aminotransferase)?

Accepted Answer

$\alpha$-ketoglutarate + alanine \rightarrow glutamate + pyruvate

Question 7

A patient presents with elevated serum CK levels after a myocardial infarction. Which process is most likely responsible for the increase?

Accepted Answer

Release of CK from damaged cardiac muscle

Question 8

Which intermediate is commonly produced during the catabolism of both glucogenic and ketogenic amino acids?

Accepted Answer

Pyruvate

Question 9

Which of the following best describes the role of tetrahydrofolate in amino acid metabolism?

Accepted Answer

It transfers single-carbon units in various oxidation states.

Question 10

A defect in the urea cycle would most likely result in which clinical finding?

Accepted Answer

Hyperammonemia

Question 11

Which of the following is a direct product of the transamination of aspartate?

Accepted Answer

Oxaloacetate

Question 12

Which enzyme is most likely to be measured in the diagnosis of acute liver injury?

Accepted Answer

ALT (alanine aminotransferase)

Question 13

Which of the following best explains why amino acid catabolism is linked to the citric acid cycle?

Accepted Answer

Amino acid carbon skeletons are converted to citric acid cycle intermediates.

Question 14

Which of the following reactions is catalyzed by AST (aspartate aminotransferase)?

Accepted Answer

Aspartate + $\alpha$-ketoglutarate \rightarrow oxaloacetate + glutamate

Question 15

Which of the following is NOT a fate of amino acid carbon skeletons after deamination?

Accepted Answer

Direct excretion in urine

Amino Acid Oxidation: Practice Questions and Key Concepts

Study Guide - Practice Questions