What would happen if in a gene encoding a polypeptide of 50 amino acids, `25^(th)` codon (UAU) is mutated to UA A?

Options

A. A polypeptide of 49 amino acids will be formed
B. A polypeptide of 25 amino acids will be formed
C. A polypeptide of 24 amino acids will be formed
D. Two polypeptides of 24 and 25 amino acids will be formed

Explanation

### Step-by-Step Solution:

1. **Understanding the Codon Mutation**: The original codon at the 25th position is UAU, which codes for the amino acid Tyrosine. The mutated codon is UAA, which is a stop codon.

2. **Identifying the Role of Stop Codons**: Stop codons (UAA, UAG, UGA) do not code for any amino acid. Instead, they signal the termination of the translation process during protein synthesis.

3. **Analyzing the Impact of the Mutation**:
- Up to the 24th amino acid, the polypeptide chain will be synthesized normally.
- When the ribosome encounters the mutated UAA codon at the 25th position, it will recognize this as a stop signal.

4. **Resulting Polypeptide Length**: Because of the premature stop signal, the translation will terminate at the 24th amino acid. Therefore, the resulting polypeptide will consist of only 24 amino acids instead of the intended 50.

5. **Conclusion**: The mutation from UAU to UAA results in a truncated polypeptide chain of 24 amino acids, which may lead to loss of function or altered function of the protein, depending on its role in the organism.