If there are 999 bases in RNA that codes for a protein with 333 amino acids, and the base at position 901 is deleted such that the length of the RNA becomes 998 bases, how many codons will be altered

Options

A. 1
B. 11
C. 33
D. 333

Answer

To solve the problem step by step, we can follow this approach:

### Step 1: Understand the relationship between bases, codons, and amino acids.
- Each codon consists of 3 bases.
- Given that there are 999 bases in the RNA, we can calculate the number of codons by dividing the total number of bases by 3.

**Calculation**:
Number of codons = Total bases / 3 = 999 / 3 = 333 codons.

### Step 2: Identify the impact of the deletion of a base.
- The question states that the base at position 901 is deleted, resulting in the RNA being 998 bases long.
- This deletion affects the codons starting from the 901st position onward.

### Step 3: Determine the number of altered codons.
- Since the deletion occurs at the 901st base, the codon that includes this base (codon 301) will be altered.
- Additionally, all subsequent codons will also be affected due to the shift in the reading frame caused by the deletion.

**Calculation**:
- The altered codons will be from codon 301 to the last codon.
- The total number of altered codons = Total codons after deletion - Codons before deletion.

**Calculation**:
- Codons before deletion = 300 (from 1 to 300).
- Codons after deletion = 333 - 300 = 33 codons altered.

### Step 4: Conclusion
- Therefore, the number of altered codons due to the deletion of the base at position 901 is 33.

### Final Answer:
The number of altered codons is **33**.

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