Q: Which of the following reactions is catalyzed by phenylalanine hydroxylase (PAH)?

$\text{Phenylalanine} + O_2 \rightarrow \text{Tyrosine}$

Question 1

Which of the following amino acids is classified as exclusively ketogenic?

Accepted Answer

Leucine

Question 2

A patient with phenylketonuria (PKU) is unable to convert phenylalanine to which amino acid due to a deficiency in phenylalanine hydroxylase?

Accepted Answer

Tyrosine

Question 3

Which intermediate is formed from the catabolism of both glucogenic and ketogenic amino acids?

Accepted Answer

Acetoacetate

Question 4

Rapidly dividing leukemic cells are unable to synthesize sufficient asparagine. Which enzyme is used therapeutically to exploit this metabolic vulnerability?

Accepted Answer

Asparaginase

Question 5

Which vitamin is required as a coenzyme for the conversion of homocysteine to methionine?

Accepted Answer

Vitamin B\_{12}

Question 6

Which of the following amino acids can be synthesized from 3-phosphoglycerate?

Accepted Answer

Serine

Question 7

A deficiency in branched-chain α-keto acid dehydrogenase (BCKD) leads to which metabolic disorder?

Accepted Answer

Maple syrup urine disease (MSUD)

Question 8

Which amino acid is both glucogenic and ketogenic?

Accepted Answer

Isoleucine

Question 9

Which of the following reactions is catalyzed by phenylalanine hydroxylase (PAH)?

Accepted Answer

$	ext{Phenylalanine} + O_2 ightarrow 	ext{Tyrosine}$

Question 10

Which amino acid is synthesized by amidation of aspartate?

Accepted Answer

Asparagine

Question 11

A patient presents with megaloblastic anemia. Which deficiency is most likely responsible, considering its role in one-carbon metabolism and DNA synthesis?

Accepted Answer

Folic acid (THF)

Question 12

Which amino acid is a precursor for the synthesis of cysteine in humans?

Accepted Answer

Methionine

Question 13

Which metabolic intermediate is produced from the catabolism of asparagine and aspartate?

Accepted Answer

Oxaloacetate

Question 14

Which of the following is a consequence of elevated homocysteine (Hey) levels in plasma?

Accepted Answer

Increased risk of occlusive vascular diseases

Question 15

Which coenzyme is required for the branched-chain α-keto acid dehydrogenase (BCKD) complex?

Accepted Answer

Thiamine pyrophosphate

Question 16

Which amino acid is synthesized from phenylalanine and becomes essential in patients with PKU?

Accepted Answer

Tyrosine

Question 17

Which of the following amino acids is NOT essential in the human diet?

Accepted Answer

Glutamine

Question 18

Which metabolic disorder is characterized by a musty odor of urine and intellectual disability if untreated?

Accepted Answer

Phenylketonuria (PKU)

Question 19

Which amino acid is synthesized by the transfer of a formyl group from tetrahydrofolate (THF) to glycine?

Accepted Answer

Serine

Question 20

Which of the following amino acids is catabolized to succinyl CoA via propionyl CoA?

Accepted Answer

Valine

Amino Acids: Degradation and Synthesis – Biochemical Pathways and Clinical Relevance

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