Question

Why do organelles like the mitochondria and chloroplasts have their own DNA?
1.They are responsible for their own replication and division in the cell.
2. All organelles have their own DNA, and these two demonstrate that property.
3. DNA is used to code for proteins, which they synthesize.
4. They used to be free-living prokaryotes that functioned as a unicellular organism

Answer 1

Organelles like mitochondria and chloroplasts have their own DNA primarily because **they used to be free-living prokaryotes that functioned as unicellular organisms**. This is supported by the endosymbiotic theory, which suggests that these organelles originated from ancient prokaryotic cells that were engulfed by ancestral eukaryotic cells. Over time, these prokaryotes became integral parts of the eukaryotic cell, yet they retained some of their genetic material, which is why they have their own DNA today.

So, the best answer to your question is:
**4. They used to be free-living prokaryotes that functioned as a unicellular organism.**