Which of the following pair have a double function?

Options

A. AUG, GUG
B. UAA, UGA
C. UGA, GUG
D. UAA, AUG

Answer

To solve the question "Which of the following pair have a double function?", we need to identify pairs of codons that serve more than one purpose in the genetic code. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Codons**: Codons are sequences of three nucleotides that correspond to specific amino acids or signals in the genetic code. Some codons can have dual functions.

2. **Identifying the Codons**:
- We have two pairs to analyze: AUG and GUG.
- AUG is known as the start codon and codes for the amino acid Methionine.
- GUG can also serve as a start codon under certain conditions and codes for Valine.

3. **Analyzing AUG**:
- AUG is the most common initiator codon, meaning it signals the start of protein synthesis and codes for Methionine.

4. **Analyzing GUG**:
- GUG typically codes for Valine, but in the absence of AUG, it can also act as an initiator codon.

5. **Conclusion**:
- Both AUG and GUG can function as initiator codons, which provides them with a dual function. Therefore, the correct answer is the pair AUG and GUG.

### Final Answer:
The correct pair that has a double function is **AUG and GUG**.

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