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

Options

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

Answer

To determine which mutations prove that codons are triplets and are read in a contiguous manner, we will analyze the types of mutations provided in the options.

### Step-by-Step Solution:

1. **Understanding Codons**:
- Codons are sequences of three nucleotides that correspond to specific amino acids in protein synthesis. This triplet nature is crucial for the correct translation of genetic information.

2. **Identifying Mutation Types**:
- The question presents three types of mutations: frame shift insertion, frame shift deletion, and substitution mutation. We need to evaluate how each affects the reading of codons.

3. **Frame Shift Insertion Mutation**:
- In a frame shift insertion mutation, an extra nucleotide is inserted into the sequence. For example, if a 'G' is inserted between two codons, the reading frame shifts, and all subsequent codons are altered.
- This change demonstrates that codons are read in triplets because the insertion affects the grouping of nucleotides into codons, leading to a completely different sequence of amino acids.

4. **Frame Shift Deletion Mutation**:
- In a frame shift deletion mutation, a nucleotide is removed from the sequence. For instance, if a 'U' is deleted, the remaining nucleotides shift, altering the reading frame.
- Similar to insertion, this mutation shows that codons are read in triplets because the deletion changes the grouping of the remaining nucleotides, resulting in a different sequence of amino acids.

5. **Substitution Mutation**:
- A substitution mutation involves replacing one nucleotide with another. For example, changing 'AUG' to 'AUG' or 'AUU' does not affect the overall number of codons or their triplet nature.
- This type of mutation does not provide evidence for codons being triplets or read contiguously, as the overall reading frame remains intact.

6. **Conclusion**:
- Both frame shift insertion and frame shift deletion mutations demonstrate that codons are triplets and are read in a contiguous manner. Therefore, the correct answer is that both mutations (1 and 2) prove the triplet nature of codons.

### Final Answer:
Both frame shift insertion and frame shift deletion mutations prove that codons are triplets and are read in a contiguous manner.

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