N-terminus of polypeptide is related to

Options

A. 3.prime of mRNA
B. 3. prime of coding strand
C. 3. prime of template
D. 5. prime of mRNA

Answer

### Step-by-Step Solution:

1. **Understanding N-terminus**: The N-terminus of a polypeptide is also known as the amino terminus. It is characterized by the presence of a free amino group (NH2) at one end of the polypeptide chain.

2. **Identifying the Role of N-terminus**: The N-terminus represents the starting point of a polypeptide or protein. This is where the synthesis of the polypeptide begins during translation.

3. **Relating N-terminus to mRNA**: During protein synthesis, the mRNA is read in the 5' to 3' direction. The N-terminus of the polypeptide corresponds to the 5' end of the mRNA strand, as the first codon that is translated into an amino acid is found at this end.

4. **Analyzing the Options**:
- **Option A (3' of mRNA)**: Incorrect, as the N-terminus does not correspond to the 3' end.
- **Option B (3' of coding strand)**: Incorrect, as it refers to the coding strand, not the polypeptide.
- **Option C (3' of template)**: Incorrect, as the template strand is not directly related to the N-terminus.
- **Option D (5' of mRNA)**: Correct, as the N-terminus corresponds to the 5' end of the mRNA.

5. **Conclusion**: The correct answer is **Option D**, which states that the N-terminus of a polypeptide is related to the **5' end of mRNA**.