Question 1

Which enzyme is responsible for the initial hydrolysis of triacylglycerols into fatty acids and glycerol during lipid catabolism?

Accepted Answer

Lipases

Question 2

During β-oxidation of fatty acids, which coenzyme is reduced in the first oxidation step catalyzed by acyl-CoA dehydrogenase?

Accepted Answer

FAD

Question 3

Which of the following best describes the main function of the urea cycle in protein metabolism?

Accepted Answer

Conversion of toxic ammonia to urea for excretion

Question 4

In the process of transamination, which molecule acts as the amino group acceptor?

Accepted Answer

$$\alpha-$$ketoglutarate

Question 5

Which of the following reactions is catalyzed by peptidyl transferase during protein synthesis?

Accepted Answer

Formation of a peptide bond between amino acids

Question 6

Which step in fatty acid synthesis involves the reduction of a carbonyl group to a hydroxyl group?

Accepted Answer

Step 4: $$\beta-$$ketoacyl-ACP reductase

Question 7

A patient with a deficiency in ornithine transcarbamylase (OTC) would most likely accumulate which metabolite?

Accepted Answer

Carbamoyl phosphate

Question 8

Which of the following best describes the role of aminoacyl-tRNA synthetase in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA.

Question 9

During the elongation phase of translation, which site on the ribosome does the incoming aminoacyl-tRNA bind to?

Accepted Answer

A site

Question 10

Which of the following is a product of oxidative deamination of an amino acid?

Accepted Answer

Ammonia ($$NH_3)$$

Question 11

Which enzyme catalyzes the hydration step in the β-oxidation of fatty acids?

Accepted Answer

Enoyl-CoA hydratase

Question 12

In the urea cycle, which amino acid is directly cleaved by arginase to release urea?

Accepted Answer

Arginine

Question 13

Which of the following statements about endopeptidases is correct?

Accepted Answer

They cleave internal peptide bonds within proteins.

Question 14

Which of the following best describes the process of alpha-decarboxylation of amino acids?

Accepted Answer

$$\mathrm{R-CH(NH_2$)-COOH \rightarrow R-CH_2$-NH_2$ + CO_2$}$$

Question 15

Which of the following is NOT a step in the translation process during protein biosynthesis?

Accepted Answer

Replication

Question 16

A defect in the enzyme carbamoyl phosphate synthetase I (CPS I) would most directly result in which clinical consequence?

Accepted Answer

Hyperammonemia due to impaired urea synthesis

Question 17

Which of the following best explains why fatty acid synthesis and β-oxidation do not occur simultaneously in the same cellular compartment?

Accepted Answer

They are regulated reciprocally to prevent futile cycling.

Question 18

Which of the following is a key regulatory step in fatty acid synthesis?

Accepted Answer

Carboxylation of acetyl-CoA to malonyl-CoA

Question 19

Which of the following best describes the fate of glycerol released during triacylglycerol catabolism in the liver?

Accepted Answer

It is converted to dihydroxyacetone phosphate (DHAP) and enters glycolysis or gluconeogenesis.

Question 20

Which of the following statements about the role of tRNA in translation is correct?

Accepted Answer

tRNA delivers specific amino acids to the ribosome according to the codon sequence on mRNA.

Lipid and Protein Metabolism: Catabolism, Biosynthesis, and the Urea Cycle

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