Frameshift insertion or deletion mutations proves that

Options

A. A codon is triplet
B. A codon is read in a contiguous manner
C. The genetic code is present on mRNA
D. Both (A) and (B)

Answer

To solve the question regarding frameshift insertion or deletion mutations, we need to understand what these mutations are and what they imply about the genetic code.

### Step-by-Step Solution:

1. **Understanding Frameshift Mutations**:
- Frameshift mutations occur when nucleotides are inserted or deleted from the DNA sequence. This alters the reading frame of the genetic code.
- The genetic code is read in triplets, known as codons, where each codon corresponds to a specific amino acid.

2. **Codon Structure**:
- A codon consists of three nucleotides. For example, the codon AUG corresponds to the amino acid Methionine.
- If one or two nucleotides are added or removed (insertion or deletion), the entire sequence of codons downstream of the mutation is shifted, leading to a completely different translation of the mRNA.

3. **Implications of Frameshift Mutations**:
- **Proves that a codon is triplet**: Since the reading frame is disrupted by the addition or removal of nucleotides, it confirms that codons are indeed made up of three nucleotides. If they were not, a deletion or insertion of one or two nucleotides would not cause such a significant shift in the reading frame.
- **Proves that a codon is read in a contiguous manner**: The fact that the reading frame shifts shows that codons are read one after the other without any gaps. If there were gaps or if they were not read continuously, the effects of insertion or deletion would not be as drastic.

4. **Conclusion**:
- Therefore, frameshift insertion or deletion mutations demonstrate that:
- A codon is triplet.
- A codon is read in a contiguous manner.
- The correct answer to the question is **both A and B**.

### Final Answer:
Both A and B.

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