Question

Which one of the following codons has dual function?

• A. AUG
• B. AUC
• C. ACU
• D. ACA

Hint:

AUG = Start codon + Methionine. UAA, UAG, UGA are stop codons. Remember the unique dual role of AUG.

Answer 1

The Correct Option is A

Step 1: Codons are sequences of three nucleotides in mRNA that specify amino acids.
Step 2: AUG is unique because it acts as a **start codon**—it signals the beginning of translation.
Step 3: In addition, AUG also codes for the amino acid **methionine**.
Step 4: No other codon has both roles—initiation and amino acid coding.
\[ \Rightarrow \text{Thus, the correct answer is } \boxed{\text{(A) AUG}}. \]