Why do organelles like mitochondria and chloroplasts have their own DNA?

Question

1. they are responsible for their own replication and division inside the cell.
2. all organelles have their own DNA, and these two demonstrate that properly.
3. DNA is used to code for proteins, which these organelles synthesize.
4. they used to be free-living prokaryotes that functioned as unicellular organisms.

Answer 1

The correct answer is:

4. they used to be free-living prokaryotes that functioned as unicellular organisms.

Mitochondria and chloroplasts are thought to have originated from ancestral prokaryotic cells through a process known as endosymbiosis. This theory suggests that these organelles were once independent bacteria that were engulfed by a larger host cell. Over time, they became integral parts of the eukaryotic cell and retained some of their own genetic material (DNA), which is why they have their own DNA today. This DNA allows them to produce some of their own proteins and replicate independently from the cell, although they also rely on the host cell for many functions.