How did endosymbiosis happen?

Question

Daniel Arnold · Accepted Answer

Mitochondria and Chloroplast were swollen.

Before endosymbiosis, cells contained mitochondria and chloroplasts; mitochondrial DNA was proposed as evidence for this. Over time, the symbiotic relationship between the host and the swollen cells developed into a strong one in which the host provides security and the swollen cells receive energy from the mitochondria and chloroplasts.

Penelope Adams · Answer

Eukaryotic cells engulfed prokaryotic cells.

The endosymbiotic theory is how scientists think mitochondria and chloroplasts evolved in eukaryotic organisms. Before mitochondria and chloroplasts were organelles in a cell, they were prokaryotes that were absorbed by eukaryotic cells.

The mitochondrion was originally a prokaryotic cell that could undergo aerobic respiration. After being absorbed by a eukaryotic cell, it developed a symbiotic relationship with its host cell.

The chloroplast was originally a prokaryotic cell that could undergo photosynthesis (eg. cyanobacteria). Like the mitochondria, the photosynthesizing bacteria became dependent on the host cell after being engulfed.

Clara Atchley · Answer

undefined Endosymbiosis is believed to have occurred when a eukaryotic cell engulfed a prokaryotic cell, forming a symbiotic relationship. Over time, the engulfed cell evolved into an organelle, such as mitochondria or chloroplasts, within the host cell. This process is thought to have happened through a series of steps, including the establishment of a mutualistic relationship between the two cells, the transfer of genetic material from the engulfed cell to the host cell's nucleus, and the evolution of mechanisms to maintain the symbiosis.