Question

The following diagram shown restriction sites in E. coli cloning vector pBR322. Find the role of ‘X’ and ‘Y’gens :

• A. The gene ‘X’ is responsible for resistance to antibiotics and ‘Y’ for protein involved in the replication of Plasmid.
• B. The gene ‘X’ is responsible for controlling the copy number of the linked DNA and ‘Y’ for protein involved in the replication of Plasmid.
• C. The gene ‘X’ is for protein involved in replication of Plasmid and ‘Y’ for resistance to antibiotics
• D. Gene ’X’ is responsible for recognitions sites and ‘Y’ is responsible for antibiotic resistance

Answer 1

The Correct Option is B

Step 1: Understanding the function of the 'X' and 'Y' genes:

The E. coli plasmid pBR322 features two key genes, 'X' and 'Y', essential for plasmid replication and stability. These genes regulate plasmid copy number and maintenance within bacterial cells.

Step 2: Role of gene 'X' (ori):

Gene 'X' in the diagram signifies the origin of replication, or ori. This sequence initiates DNA replication and controls the copy number of associated DNA, ensuring efficient plasmid replication.

Step 3: Role of gene 'Y' (rop):

Gene 'Y' corresponds to rop, which encodes a protein instrumental in plasmid replication. The rop protein stabilizes plasmid replication by managing the number of plasmid copies and aiding plasmid maintenance during cell division.

Step 4: Conclusion:

In summary, the diagram shows:

• 'X' is ori: The origin of replication, controlling linked DNA copy number.
• 'Y' is rop: A gene encoding a protein involved in plasmid replication.

Incorrect Options: Options (1), (3), and (4) are inaccurate as their assigned roles for 'X' and 'Y' do not match the functions of the origin of replication (ori) and the rop gene.

Answer: The correct answer is Option 1.