Extra chromosomal DNA occurs in

Options

A. Mitochondria
B. Ribosomes
C. Nucleus
D. Chromosomes

Answer

**Step-by-Step Solution:**

1. **Understanding Extra Chromosomal DNA**:
- Extra chromosomal DNA refers to genetic material that is not located within the nucleus of a cell. It is often found in the cytoplasm or within certain organelles.

2. **Identifying the Options**:
- The options provided are mitochondria, ribosomes, nucleus, and chromosomes. We need to determine which of these contains extra chromosomal DNA.

3. **Analyzing Each Option**:
- **Mitochondria**: These are organelles known as the powerhouse of the cell. They contain their own DNA, which is separate from the nuclear DNA. This DNA is circular and resembles bacterial DNA, indicating that mitochondria evolved from ancestral prokaryotic cells.
- **Ribosomes**: These are not organelles that contain DNA. Instead, they are the sites of protein synthesis and do not have their own genetic material.
- **Nucleus**: The nucleus contains the cell's chromosomal DNA, which is the primary genetic material, and does not qualify as extra chromosomal DNA.
- **Chromosomes**: These are structures within the nucleus that contain the cell's genetic information. They are not considered extra chromosomal DNA.

4. **Conclusion**:
- The only option that contains extra chromosomal DNA is **mitochondria**. Therefore, the correct answer is mitochondria.

**Final Answer**: Extra chromosomal DNA occurs in **mitochondria**.

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