Question

which prokaryotes are most closely related to mitochondria? the first eukaryotes acquired mitochondria by endosymbiosis. in studying which living prokaryotes might be most closely related to the ancestor of mitochondria, researchers isolated and cloned nucleotide sequences from the gene that codes for the small-subunit rrna molecule for six organisms:

Answer 1

Mitochondria are strongly related to alpha-proteobacteria, as suggested by the endosymbiotic theory. They have their own DNA, ribosomes similar to prokaryotes, and a symbiotic origin, confirming their prokaryotic ancestry.

Step-by-step explanation:

Mitochondria are believed to be descendants of prokaryotes based on the endosymbiotic theory. These organelles have their own DNA, replicate through a process similar to bacterial binary fission, and share structural similarities with the ribosomes and DNA of alpha-proteobacteria. Evidence indicates that mitochondria were once free-living prokaryotes that entered into a symbiotic relationship with ancient eukaryotic cells, providing essential ATP to their host in exchange for protection. Over time, this association became permanent, transferring many mitochondrial genes to the host eukaryotic nucleus, making mitochondria an indispensable part of the eukaryotic cell structure.

Evidence of Endosymbiosis

The presence of circular chromosomes, ribosomes resembling those of prokaryotes, and the movement of genes from mitochondria to the nuclear genome suggest a strong link to alpha-proteobacteria, the group most closely related to the ancestral mitochondria. While research continues to reveal the intricate history of eukaryotic and prokaryotic evolution, the endosymbiotic theory, widely accepted by biologists today, illustrates a critical evolutionary step towards complex eukaryotic life.