A: Peptidyl transfer site is contributed by larger sub-unit of ribosome.
R: The enzyme peptidyl transferase is contributed by the both 23S and 16S ribosomal sub-units .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark
B. If both Assertion & Reason are true and the reason is not the correct explanation of the assertion , then mark
C. If Assertion is true statement but Reason is false, then mark.
D. If both Assertion and Reason are false statements, then mark.

Answer

To solve the assertion and reason question, we will analyze both statements provided in the question step by step.

### Step 1: Analyze the Assertion
The assertion states that "the peptidyl transfer site is contributed by the larger subunit of the ribosome."
- The larger subunit of the ribosome (in prokaryotes, this is the 50S subunit, and in eukaryotes, it is the 60S subunit) indeed contains the peptidyl transferase activity. This site is crucial for the formation of peptide bonds during protein synthesis.

**Conclusion for Step 1**: The assertion is true.

### Step 2: Analyze the Reason
The reason states that "the enzyme peptidyl transferase is contributed by both 23S and 16S ribosomal subunits."
- In prokaryotes, the 23S rRNA (which is part of the 50S subunit) is responsible for the peptidyl transferase activity. The 16S rRNA (which is part of the 30S subunit) does not have peptidyl transferase activity; it plays a role in the initiation and decoding of mRNA. Therefore, this statement is misleading because it implies that both subunits contribute to the peptidyl transferase activity, which is not correct.

**Conclusion for Step 2**: The reason is false.

### Step 3: Final Evaluation
- Since the assertion is true and the reason is false, we conclude that while both statements are not correct in relation to each other, the assertion stands true on its own.

### Final Answer
- Assertion (A) is true.
- Reason (R) is false.