Question

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

DNA is used to code for proteins, which these organelles synthesize.

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

They are responsible for their own replication and division inside the cell.

All organelles have their own DNA, and these two demonstrate that property.

Answer 1

The best explanation for why organelles like mitochondria and chloroplasts have their own DNA is:

**They used to be free-living prokaryotes that functioned as unicellular organisms.**

This theory is part of the endosymbiotic theory, which posits that mitochondria and chloroplasts originated from free-living prokaryotic organisms that were engulfed by ancestral eukaryotic cells. Over time, these prokaryotes developed a symbiotic relationship with their hosts, eventually becoming integral components of the eukaryotic cells. Their own DNA is a remnant of their prokaryotic ancestry and is involved in coding for some of the proteins needed for their specific functions. Thus, the presence of their own DNA supports the understanding of their evolutionary history.