Understanding:
• The origin of eukaryotic cells can be explained by the endosymbiotic theory
An endosymbiont is a cell which lives inside another cell with mutual benefit
Eukaryotic cells are believed to have evolved from early prokaryotes that were engulfed by phagocytosis
The engulfed prokaryotic cell remained undigested as it contributed new functionality to the engulfing cell (e.g. photosynthesis)
Over generations, the engulfed cell lost some of its independent utility and became a supplemental organelle
Overview of the Process of Endosymbiosis
Evidence for Endosymbiosis
Mitochondria and chloroplasts are both organelles suggested to have arisen via endosymbiosis
Evidence that supports the extracellular origins of these organelles can be seen by looking at certain key features:
- Membranes (double membrane bound)
- Antibiotics (susceptibility)
- Division (mode of replication)
- DNA (presence and structural composition)
- Ribosomes (size)
Mnmemonic: MAD DR (mad doctor)
Chloroplast and Mitochondrial Evidence
