Which of the following is an ambiguous codon?

Options

A. AUG
B. GUG
C. UGA
D. GAG

Answer

To determine which of the following is an ambiguous codon, we need to understand the concept of codons in the genetic code.

### Step-by-Step Solution:

1. **Understanding Codons**: Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids or stop signals during protein synthesis. Each codon is made up of three bases (nucleotides).

2. **Properties of Codons**: The genetic code has several important properties:
- Codons are triplet sequences.
- Each codon specifies only one amino acid (non-ambiguity).
- There are start and stop codons.
- The genetic code is universal across different organisms.

3. **Ambiguous Codons**: An ambiguous codon is one that can specify more than one amino acid depending on its context or position. This is contrary to the non-ambiguous nature of most codons, where each codon corresponds to only one specific amino acid.

4. **Identifying Ambiguous Codons**: In the context of the question, we need to identify which codon can code for more than one amino acid. The example given in the transcript is GAG, which typically codes for glutamic acid but can also code for methionine when in the initiator position.

5. **Conclusion**: Based on the information provided, the ambiguous codon among the options is GAG, as it can represent different amino acids depending on its position in the mRNA sequence.

### Final Answer:
The ambiguous codon is **GAG**.

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