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

Answer 1

The Correct Option is D

The question evaluates the knowledge of genetic codons and the amino acids they code for. Let's examine each statement individually:

1. Statement I: The codon 'AUG' codes for methionine and phenylalanine.
   • The genetic code is a set of rules used by living cells to translate information encoded within genetic material into proteins. Each codon, a sequence of three nucleotides, encodes a specific amino acid.
   • 'AUG' is an important codon because it serves two functions: it codes for the amino acid methionine and also acts as the start codon in the process of translation in protein synthesis.
   • However, 'AUG' only codes for methionine, not phenylalanine. Phenylalanine is encoded by the codons 'UUU' and 'UUC'.
   • Hence, Statement I is incorrect.
2. Statement II: 'AAA' and 'AAG' both codons code for the amino acid lysine.
   • Each amino acid is encoded by a specific set of codons. Lysine is one of the twenty standard amino acids used by cells to construct proteins.
   • Both 'AAA' and 'AAG' codons indeed code for the amino acid lysine.
   • Therefore, Statement II is true.

Based on the analysis of both statements:

• Statement I is incorrect because 'AUG' only codes for methionine, not phenylalanine.
• Statement II is true as both 'AAA' and 'AAG' codons do indeed code for lysine.

Therefore, the correct answer is: Statement I is incorrect but Statement II is true.