Extrachromosomal DNA of bacteria is

Options

A. Mesosome
B. Microsome
C. Plasmid
D. Chromosome.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the extrachromosomal DNA found in bacteria. Extrachromosomal DNA refers to DNA that is not part of the chromosomal DNA.

2. **Identifying Options**: The options provided are:
- Option 1: Mesosome
- Option 2: Microsome
- Option 3: Plasmid
- Option 4: Chromosome

3. **Analyzing Each Option**:
- **Mesosome**: This is a structure in bacterial cells that is involved in cell division and respiration but does not contain extrachromosomal DNA.
- **Microsome**: This term generally refers to fragments of the endoplasmic reticulum in eukaryotic cells and is not relevant to bacterial DNA.
- **Plasmid**: Plasmids are small, circular pieces of DNA that exist independently of chromosomal DNA in bacteria. They often carry genes that provide beneficial traits, such as antibiotic resistance.
- **Chromosome**: This is the main DNA structure in bacteria that contains the essential genetic information. It is not considered extrachromosomal.

4. **Conclusion**: Based on the analysis, the correct answer is **Plasmid** (Option 3), as it is the only option that represents extrachromosomal DNA in bacteria.

5. **Final Answer**: The extrachromosomal DNA of bacteria is **Plasmid**.

---