Cellsclassification depends on whether the cells have a nucleus or not.The two classes are namely the eukaryotic cell (cells that have anucleus, for example, fungi) and prokaryotic cells (cells that lack anucleus, for example, Bacteria). Records of fossils show thateukaryotes evolved from prokaryotes. This evolution occurred about 2billion years ago. Eukaryotes are said to have come about when twosmall prokaryotes invaded one larger prokaryote and became part ofone large cell with additional features, and that could performadditional functions. The two ways in which the invasion occurred areendosymbiosis and membrane in-folding.
Inendosymbiosis, two separate prokaryotic cells merge to form a largereukaryotic cell by directly invading the prokaryotic cell as aparasite or as an indigestible food. In membrane in-folding, theouter membrane of the host prokaryotic cell folded inwards tosurround the attacking prokaryotic cells, transporting then insidethe cell.
Endosymbiosisresults in the formation of larger cells that work more effectively.Research has shown that eukaryotic cells are a thousand times largerthan prokaryotic cells. As a result of endosymbiosis, eukaryoticcells have different organelles, each performing a distinct function.For example, chloroplast in green plants aids in photosynthesis andthe Golgi apparatus transport proteins for secretion out of the cell.
Theprocess of endosymbiosis results in one organism acquiringcharacteristics of the cells that form it. This process is theprimary unit of the acquisition of traits from one living thing toanother. For example, I look more like my mum than my dad. I acquiredmore features from my mum such as the facial formation of my mouthand cheeks. I am also asthmatic like my mother and my grandmother.However, I do have features acquired from my dad’s genes such assome of my fingers and toes resemble his.
Volpe,E. P., & Rosenbaum, P. A. (2000). Understandingevolution.Boston: McGraw-Hill.