Which cell organelles have its own DNA ?

Question

Accepted Answer

Mitochondria and plastids are unique among cell organelles because they contain their own DNA, which is why Option 4 is the correct answer.

1. **Explanation for Option 4 (Correct Answer):**
   - **Mitochondria:** These organelles are known as the powerhouses of the cell because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. Mitochondria have their own circular DNA, which is separate from the nuclear DNA. This mitochondrial DNA is inherited maternally and is responsible for encoding some of the proteins and enzymes required for mitochondrial function.
   - **Plastids:** These are a group of organelles found in the cells of plants and algae. The most well-known type of plastid is the chloroplast, which is involved in photosynthesis. Like mitochondria, plastids also contain their own circular DNA. This DNA is crucial for the synthesis of proteins needed for the organelle's functions, such as photosynthesis in chloroplasts.

2. **Explanation for why other options are incorrect:**
   - **Option 1 (Lysosomes):** Lysosomes are membrane-bound organelles that contain enzymes for digesting macromolecules, old cell parts, and microorganisms. They do not have their own DNA. Instead, the enzymes and proteins required for lysosomal function are encoded by nuclear DNA and synthesized in the cytoplasm before being transported to the lysosome.
   - **Option 2 (Mitochondria):** While mitochondria do have their own DNA, this option alone does not account for plastids, which also have their own DNA. Therefore, Option 2 is incomplete.
   - **Option 3 (Plastids):** Similarly, while plastids have their own DNA, this option alone does not include mitochondria, making it incomplete as well.

In conclusion, both mitochondria and plastids possess their own DNA, which is why Option 4, "Both (2) and (3)," is the correct answer.