Opal

Options

A. UAA
B. UAG
C. GUG
D. UGA

Answer

**Step-by-Step Solution:**

1. **Understanding Codons**: Codons are sequences of three nucleotides that correspond to specific amino acids or signal the termination of protein synthesis.

2. **Identifying Stop Codons**: The question asks about the opal codon. We need to identify the stop codons among the given options: UAA, UAG, GUG, and UGA.

3. **Listing the Stop Codons**: The known stop codons in the genetic code are:
- UAA (also known as ochre)
- UAG (also known as amber)
- UGA (also known as opal)

4. **Analyzing the Options**:
- UAA is a stop codon (ochre).
- UAG is a stop codon (amber).
- GUG is not a stop codon; it codes for the amino acid valine.
- UGA is a stop codon (opal).

5. **Conclusion**: Among the options provided, UGA is identified as the opal codon.

**Final Answer**: The opal codon is UGA.

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