Which of the following mutations prove(s) that codon is a triplet and it is read in a contiguous manner?

Options

A. Frame - shift insertion mutation
B. Frame- shift deletion mutation
C. Substitution mutation
D. Both (1) and (2)

Answer

To solve the question regarding which mutations prove that codons are triplets and read in a contiguous manner, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Codons**: Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids. This triplet nature is essential for the genetic code.

2. **Identifying Types of Mutations**: There are two main types of mutations that can affect the reading frame of the genetic code:
- **Frameshift Mutation**: This occurs when nucleotides are inserted or deleted from the sequence, causing a shift in the reading frame. This can happen with:
- One deletion
- Two deletions
- One insertion
- Two insertions

3. **Example of Frameshift Mutation**: Consider the phrase "Ram has red cap". If we delete a letter (e.g., 'r' from 'red'), the phrase changes to "Ram has ed cap", which alters the meaning and shifts the reading frame. This illustrates how codons are read in a contiguous manner.

4. **Conclusion on Codon Nature**: Since frameshift mutations change the entire sequence of amino acids downstream from the mutation point, they demonstrate that codons are read in triplets and that the reading is continuous.

5. **Selecting the Correct Answer**: Based on the explanation, the mutations that lead to frameshift changes (either through deletions or insertions) are the ones that prove the triplet nature of codons. Therefore, the correct answer to the question is option number 4, which includes both types of mutations.