Mitochondria were acquired by host cells through a process called endosymbiosis. This process involves a prokaryotic cell, likely an ancestral bacterium, being engulfed by an ancestral eukaryotic cell. The key points about this acquisition include:
-
Endosymbiotic Theory: This theory suggests that mitochondria originated from free-living aerobic bacteria that were taken up by ancestral eukaryotic cells. Over time, these bacteria and the host cells formed a symbiotic relationship.
-
Mutualism and Dependency: Once inside the host cell, the engulfed bacteria began to provide energy (in the form of ATP) to the host cell, while the host cell provided protection and nutrients to the bacteria. Eventually, the bacteria became dependent on the host cell, leading to the evolution of mitochondria as organelles.
-
Double Membrane: Mitochondria have a double membrane structure, which supports the idea of their origin from a prokaryotic ancestor, as they still retain some of their own DNA and replicate independently of the cell.
-
Genetic Evidence: Mitochondrial DNA is distinct from nuclear DNA and is more similar to the DNA of certain prokaryotes, particularly alpha-proteobacteria, which is consistent with the endosymbiotic theory.
In summary, the acquisition of mitochondria by host cells is accurately described by the endosymbiotic theory, highlighting the evolutionary relationship between prokaryotic ancestors and eukaryotic cells.
1 answer