Is it true mitochondria and chloroplasts originated in bacteria?

Answer 1

It is thought that chloroplasts and mitochondria were prokaryotic organisms and they were engulfed by a eukaryotic organism and instead of being digested by the cell a symbiotic relationship was formed. this is called endosymbiosis. the first scientist to pioneer this kind of thinking was Mereschkowsky back in 1905.

Taking chloroplast as the example, most of the genes from the chloroplast genome have been intergrated into the nulcear genome. Those that are left are conserved in both the chloroplast genome and the cyanobacteria genome. (the cyanobacteria is the prokaryotic organisms that is thought to have been engulfed, thus creating the ancestor to the modern chloroplast). For example, the gene for bacterial cell division is also found in the chloroplast genome. Comparing both the modern chloroplast genome and the modern cyanobacteria genome it is possilbe to see just how many genes that where originally chloroplast based have jumped ship and gone to the nuclear genome.

Both animals and plants contain mitochondria but only plants contain chloroplasts. This suggests that the endosymbiotic relationship between the eukaryotic cell and the mitcohondria happen before the animal and plant lines diverged.

Answer 2

Yes, it is believed that mitochondria and chloroplasts originated from bacteria through a process called endosymbiosis. This theory proposes that ancient eukaryotic cells engulfed free-living bacteria, which eventually formed a symbiotic relationship, leading to the development of these organelles within the cell.

Answer 3

As a theory, they originated as prokaryotic organisms and through endosymbiotic relationships, eventually formed with more complex eukaryotes as energy processors and creators

Answer 4

They are the same size as bacteria, they contain DNA, They are not derived from the endomembrane system as other organelles are,