Question

Which of the following hormones are amino acid derivatives?
A. Epinephrine
B. Serotonin
C. GABA
D. Thyroxine
E. Vasopressin
Choose the correct answer from the options given below:

• A. A and C only
• B. A, B and D only
• C. B and D only
• D. C and E only

Hint:

Tyrosine is the precursor for both catecholamines (epinephrine, norepinephrine, dopamine) and thyroid hormones (thyroxine, triiodothyronine). Tryptophan is the precursor for serotonin and melatonin.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Hormones are chemically classified into three major groups: peptide/protein hormones, steroid hormones, and amino acid derivatives (typically derived from tyrosine or tryptophan).

Step 2: Detailed Explanation:
Let us analyze each of the listed compounds:
- Epinephrine (A): A catecholamine hormone produced by the adrenal medulla, synthesized from the amino acid tyrosine.
- Serotonin (B): A monoamine neurotransmitter and hormone synthesized from the essential amino acid tryptophan.
- GABA (C): Gamma-aminobutyric acid is an inhibitory neurotransmitter synthesized from glutamate. It is not traditionally classified as an endocrine hormone.
- Thyroxine (D): A thyroid hormone (\(T_4\)) synthesized by iodinating tyrosine residues on thyroglobulin in thyroid follicular cells.
- Vasopressin (E): Also known as antidiuretic hormone (ADH), this is a peptide hormone composed of nine amino acids, synthesized in the hypothalamus.
Therefore, Epinephrine, Serotonin, and Thyroxine are classic amino acid-derived hormones.

Step 3: Final Answer:
The hormones that are amino acid derivatives are Epinephrine, Serotonin, and Thyroxine (A, B and D only).