SBA — Single Best Answer · Review
Question 514
Endocrinology → General
Classification
Question
SSBAQuestion Header
Which pairing correctly identifies the amino-acid precursor of the hormone?
Question Stem
Select the single best answer.
Options
A
Melatonin — tyrosine
B
Adrenaline — tryptophan
C
Thyroxine — tryptophan
D
Melatonin — tryptophan
E
Dopamine — tryptophan
Explanation
Melatonin is derived from tryptophan. Thyroid hormones and the catecholamines adrenaline, noradrenaline and dopamine are derived from tyrosine.
Option Validity
A) Melatonin is derived from tryptophan rather than tyrosine.
B) Adrenaline is derived from tyrosine rather than tryptophan.
C) Thyroid hormones are derived from tyrosine rather than tryptophan.
E) Dopamine is derived from tyrosine rather than tryptophan.
Further Reading
Saxena, MRCOG-1 Basic Sciences, Endocrinology: Chemical Structure of Hormones.