Pick out the expression regarding pBR 322 and Eco RI :

Options

A. Former is polymer of amino acids , where as the latter is a polymer of with catalytic activity
B. Both are redesigned plasmids
C. Former is a linear DNA where as latter is syntesized on 70s ribosomers
D. Both are organic molecules with ester bonds .

Answer

To solve the question regarding the expressions related to pBR322 and Eco RI, we need to analyze the provided statements one by one and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding pBR322**:
- pBR322 is a plasmid, which is a small, circular piece of DNA found in bacteria. It is not a polymer of amino acids; rather, it is made up of nucleic acids (DNA).

2. **Understanding Eco RI**:
- Eco RI is a restriction enzyme that cuts DNA at specific sequences. It is not a plasmid but an enzyme that facilitates the manipulation of DNA.

3. **Evaluating the Statements**:
- **Statement 1**: "PBR322 is a polymer of amino acids."
- This is incorrect because pBR322 is a plasmid (DNA), not a protein (which is made of amino acids).

- **Statement 2**: "Both are redesigned plasmids."
- This is incorrect because only pBR322 is a plasmid; Eco RI is not a plasmid.

- **Statement 3**: "PBR322 is a linear DNA."
- This is incorrect because pBR322 is circular DNA, not linear.

- **Statement 4**: "Both are organic molecules with ester bonds."
- This statement is correct. Both pBR322 (as a nucleic acid) and Eco RI (as a protein) are organic molecules, and they contain ester bonds (the bonds in nucleic acids and the bonds in proteins).

4. **Conclusion**:
- The correct expression regarding pBR322 and Eco RI is the fourth statement: "Both are organic molecules with ester bonds."

### Final Answer:
The correct expression regarding pBR322 and Eco RI is: **"Both are organic molecules with ester bonds."**