Question

Two amino acids of the standard 20 contain sulfur atoms. They are:   

A) cysteine and serine.  

B) cysteine and threonine.  

C) methionine and cysteine  

D) methionine and serine  

E) threonine and serine.

Answer 1

The correct answer is C) methionine and cysteine.

Methionine is an essential amino acid and is one of the first amino acids incorporated into proteins during translation. It contains a sulfur atom in its side chain.

Cysteine is a non-essential amino acid that contains a thiol (-SH) group in its side chain, which can form disulfide bonds with other cysteine residues to stabilize protein structure.