________ are self replicating, extra chromosomal segments of double stranded circular and naked DNA, present in a bacterial cell.

Options

A. Plasmids
B. Nucleoid
C. Mesosomes
D. Bacteriophages

Answer

To answer the question, we need to identify the term that describes self-replicating, extra-chromosomal segments of double-stranded circular and naked DNA found in bacterial cells. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a specific term that describes a type of DNA found in bacterial cells. This DNA is characterized as being self-replicating, extra-chromosomal, double-stranded, circular, and naked.

2. **Analyzing the Options**: The options provided are:
- A) Plasmid
- B) Nucleoid
- C) Mesosomes
- D) Bacteriophages

3. **Defining Each Option**:
- **Plasmid**: These are small, circular, double-stranded DNA molecules that are separate from chromosomal DNA and can replicate independently. They are often involved in genetic engineering as vectors.
- **Nucleoid**: This refers to the region within a prokaryotic cell where the chromosomal DNA is located. It is not a separate DNA segment.
- **Mesosomes**: These are infoldings of the plasma membrane in bacteria and are not related to DNA.
- **Bacteriophages**: These are viruses that infect bacteria, not segments of bacterial DNA.

4. **Identifying the Correct Answer**: Given the definitions, plasmids fit the description perfectly as they are self-replicating, extra-chromosomal, double-stranded, circular, and naked DNA present in bacterial cells.

5. **Final Answer**: Therefore, the correct answer to the question is **Plasmid**.