Question

What is the endosymbiont hypothesis? What kind of organism was engulfed to become the endosymbiont? What kind of organism did the engulfing?

Answer 1

The endosymbiotic hypothesis is for the origin of mitochondria and chloroplasts, two organelles contained within various eukaryotic cells. According to this hypothesis, these organelles originated as separate prokaryotic organisms that were taken inside a primordial eukaryotic cell.

Mitochondria Chloroplast are believed to be originated

Endosymbiont was Prokaryotes and the engulfing organism was primordial eukaryotes.

from Bacteria according to Endosymbiotic theory. Mitochondria and chloroplasts have similarities to bacteria cells. They have their own DNA, which is separate from the DNA found in the nucleus of the cell. And both organelles use their DNA to produce many proteins and enzymes required for their function. A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host. The two organelles also reproduce like bacteria, replicating their own DNA and directing their own division.