Question

How many of the following amino acids are coded by only one codon?
Tryptophan, arginine, methionine, valine, leucine.

Answer 1

The sequence of nucleotides in DNA that determines the sequence of amino acids in a polypeptide via an mRNA intermediate is known as genetic code.

The genetic code is a triplet code. Three consecutive nucleotides in mRNA constitute a codon which codes for a particular amino acid.

Mostly the amino acids are coded by more than one codon.

For example, leucine is an amino acid which is coded by six different codons (UUA, UUG, CUU, CUC, CUA, CUG).

Arginine is also coded by six different codons (CGU, CGC, CGA, CGG, AGA, AGG).

Valine is coded by four different codons (GUC, GUU, GUG, GUA).

Amino acids like tryptophan and methionine are coded by only one codon.
UGG codes for tryptophan.
AUG codes for methionine.