Final answer:
Mitochondria and chloroplasts originated from aerobic and photosynthetic prokaryotes through endosymbiosis, providing significant advantages to the host eukaryotic cells and contributing to the evolution of complex life.
Step-by-step explanation:
Mitochondria and Chloroplasts Evolution through Endosymbiosis
The endosymbiotic theory, first proposed by Lynn Margulis, explains the origin of organelles within eukaryotic cells, specifically the mitochondria and chloroplasts. Mitochondria likely evolved from aerobic prokaryotes that were engulfed by primitive eukaryotic cells.
This endosymbiotic relationship benefited both cells, as the prokaryotes supplied energy from waste breakdown to the host cell. Similarly, chloroplasts originated from photosynthetic cyanobacteria that were also internalized by eukaryotic cells, enabling the host cell to obtain food produced via photosynthesis from the engulfed bacteria.
Evidence for this includes the presence of prokaryote-like DNA within mitochondria and chloroplasts, their size and structure resemblance to bacteria, their double membrane characteristic, and their autonomous replication within eukaryotic cells.
Mitochondria are believed to have been incorporated into ancestral eukaryotic cells before chloroplasts, a sequencing evidenced by the primary role of mitochondria in generating energy necessary for a host of cellular processes, which likely gave early eukaryotes a significant evolutionary advantage. This precedence is crucial in the transition from prokaryotic to eukaryotic life.