Question

Tyrosine is a precursor of which of the following?

• A. Melanin
• B. Epinephrine
• C. Norepinephrine
• D. All of the above

Answer 1

The correct option is D All of the above

• Tyrosine is an alcoholic group-containing amino acid. Tyrosine gives rise to a family of catecholamines that includes dopamine, norepinephrine, and epinephrine.
• Phenylalanine is another important amino acid. Hydroxylation of phenylalanine yields tyrosine. Phenylalanine, after its hydroxylation to yield tyrosine, is also the precursor of the hormones epinephrine and norepinephrine, secreted by the adrenal medulla, the neurotransmitter dopamine, and melanin, the black pigment of skin and hair.

So, the correct answer is option D.