Question

Statement I: The codon 'AUG' codes for methionine and phenylalanine.

Statement II : 'AAA' and 'AAG' both codons code for the amino acid lysine.

In the light of the above statements, choose the correct answer from the options given below.

• A. Statement I is incorrect but Statement II is true
• B. Both Statement I and Statement II are true
• C. Both Statement I and Statement II are false
• D. Statement I is correct but Statement II is false

Answer 1

The correct option is A Statement I is incorrect but Statement II is true

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.

Amino acids like tryptophan and methionine are coded by only one codon.

AUG codes for methionine only.

Hence, statement I is incorrect.

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

For example, lysine is coded by two different codons, AAA and AAG.

Hence, statement II is correct.