Biologia - program rozszerzony
|Endosymbiotic theory||Theory proposing that eukaryotic cells formed from a symbiotic relationship among prokaryotic cells|
How do prokaryotic and eukaryotic cells differ?
|Genetic information||DNA is circular, usually free-floating in cytoplasm||DNA is linear, found in nucleus|
|Organelles||No nucleus or membrane-bound organelles||Has nucleus and membrane-bound organelles (ie: mitochondria, chloroplasts, Golgi body, ER)|
|Size||Small (1-5 micrometers)||Larger (10-100 micrometers)|
|Organisms||Bacteria/archaea||Animals, plants, fungi, protists|
|Cell structure||Always unicellular||Can be unicellular or multicellular|
What is the endosymbiotic theory?
One theory that may explain how eukaryotes became so complex is the endosymbiotic theory.
This theory proposes that organelles like mitochondria and chloroplasts were once free-living prokaryotic cells that began to live within a larger host cell. Over a long time, the prokaryotes and their hosts evolved together until one could not function without the other.
Często spotykane błędy i nieporozumienia
- Eukaryotes can be unicellular. Many people think that eukaryotes are all multicellular, but this is not the case. While prokaryotes are always unicellular organisms, eukaryotes can be either unicellular or multicellular. For example, most protists are single-celled eukaryotes!
- Even though prokaryotes do not have a nucleus, they DO contain genetic information. Prokaryotes generally have single circular chromosomes where they store their genetic information.