A mutational event which changes the codon UGG to UAG is known as

Options

A. gross mutation
B. mis-sense mutation
C. nonsense mutation
D. frame shift utation

Answer

To determine the type of mutational event that changes the codon UGG to UAG, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Codons**:
- The original codon is UGG, which codes for the amino acid tryptophan.
- The mutated codon is UAG, which is one of the stop codons.

2. **Understand Mutation Types**:
- **Gross Mutation**: This involves larger changes in the genome, affecting larger segments of DNA.
- **Missense Mutation**: This is a point mutation where a single nucleotide change results in a codon that codes for a different amino acid.
- **Nonsense Mutation**: This is a point mutation that converts a codon into a stop codon, leading to premature termination of protein synthesis.
- **Frameshift Mutation**: This occurs due to the insertion or deletion of nucleotides, which shifts the reading frame of the codons.

3. **Analyze the Change**:
- The change from UGG (tryptophan) to UAG (stop codon) results in the termination of protein synthesis. This indicates that the mutation has created a stop codon.

4. **Conclusion**:
- Since the mutation changes a codon that originally coded for an amino acid into a stop codon, it is classified as a **nonsense mutation**.

### Final Answer:
The mutational event which changes the codon UGG to UAG is known as a **nonsense mutation**.

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