Mutation altering nucleotide sequence within a gene are

Options

A. Frame shif mutations
B. Base pair substitution
C. Both A and B
D. None of the above

Answer

To solve the question "Mutation altering nucleotide sequence within a gene are," we need to analyze the options provided and understand the types of mutations.

### Step-by-Step Solution:

1. **Understanding Mutations**:
- Mutations are changes in the nucleotide sequence of DNA. They can occur in various forms, and understanding these forms is crucial to answering the question.

2. **Analyzing Option A - Frameshift Mutation**:
- A frameshift mutation occurs when nucleotides are added or deleted from the DNA sequence. This shifts the reading frame of the genetic code, leading to changes in the amino acids produced.
- For example, if we have a sequence of nucleotides that codes for amino acids, adding or removing a nucleotide will change the grouping of the remaining nucleotides into codons, thus altering the resulting protein.

3. **Analyzing Option B - Base Pair Substitution**:
- A base pair substitution involves replacing one nucleotide with another. This can lead to three possible outcomes:
- No change in the amino acid (silent mutation),
- A different amino acid being produced (missense mutation),
- A premature stop codon (nonsense mutation).
- However, this type of mutation does not alter the overall nucleotide sequence length, just the identity of specific nucleotides.

4. **Evaluating the Options**:
- **Option A (Frameshift mutation)**: This type of mutation alters the nucleotide sequence significantly by changing the reading frame.
- **Option B (Base pair substitution)**: This type does alter the nucleotide sequence but in a less drastic way than frameshift mutations.
- **Option C (Both A and B)**: Since both types of mutations can alter the nucleotide sequence, this option seems plausible.
- **Option D (None of the above)**: This option can be dismissed since we have identified mutations that alter nucleotide sequences.

5. **Conclusion**:
- The correct answer is **Option C (Both A and B)**, as both frameshift mutations and base pair substitutions can alter the nucleotide sequence within a gene.

### Final Answer:
**Option C: Both A and B**

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