Question

Which of the following statements about plasmids is incorrect?

• A. Plasmids have the ability to replicate within the bacterial cell.
• B. Their replication is controlled by chromosomal DNA.
• C. They are autonomously replicating circular extra-chromosomal DNA.
• D. They often carry antibiotic resistant genes.

Hint:

Plasmids are "autonomous," which is the scientific word for "self-governing" or "independent" regarding replication.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Plasmids are small, circular, double-stranded DNA molecules that are distinct from a cell's chromosomal DNA.
Step 2: Detailed Explanation:
Let's evaluate the statements:
(A) Plasmids can replicate within bacterial cells. This is correct.
(B) Plasmids are autonomously replicating, meaning their replication is not controlled by the chromosomal DNA. They have their own origin of replication (ori). This statement is incorrect.
(C) They are defined as circular, extra-chromosomal, and autonomously replicating. This is correct.
(D) Many plasmids carry genes that provide a selective advantage, such as antibiotic resistance (e.g., the ampicillin resistance gene in pBR322). This is correct.
Step 3: Final Answer:
Statement (B) is the false statement regarding plasmids.