Question

Two RNAs shown below were used separately as templates in an in vitro translation system, which can generate proteins in all possible reading frames. \[ RNA_1: 5' - (AG)_n - 3' \quad \text{and} \quad RNA_2: 5' - (AAG)_n - 3' \] The RNA_1 translated product contained Arg and Glu. The RNA_2 translated product contained Arg, Glu, and Lys. Which one of the following codons directs the incorporation of Arg?

• A. AAG
• B. AGA
• C. GAA
• D. GAG

Hint:

The codons for Arginine are AGA and AGG, while AAG codes for Lysine.

Answer 1

The Correct Option is B

Step 1: Understanding the Codon and Amino Acid Relationship.
The codon for Arginine (Arg) is either AGA or AGG in the standard genetic code. We know that the RNA sequence \( RNA_1 \) produces a protein with Arg and Glu, while \( RNA_2 \) produces Arg, Glu, and Lys.
Step 2: Analyzing the Codons.
- (A) AAG: This codon codes for Lysine, not Arginine.
- (B) AGA: This codon codes for Arginine, which matches the requirement for incorporating Arg in the translation product of \( RNA_2 \).
- (C) GAA: This codon codes for Glutamic acid (Glu), not Arginine.
- (D) GAG: This codon also codes for Glutamic acid (Glu), not Arginine.
Step 3: Conclusion.
The correct answer is (B) AGA, which codes for Arginine.