First off the cell “The structural, functional and biological unit of all organisms”. Robert Hooke made the first definitive observations of the cell in the 17th century. Cells exist as either Prokaryotic cells that lack a true nucleus( membrane enclosed) or Eukaryotic cells that have a membrane enclosed nucleus encapsulating their DNA
Prokaryotic cells are mainly bacteria and are unicellular and have existed almost 3.5 billion years ago, they very small and differ alot from eukaryotic cells. Eukaryotes are more complex cells possessing membranes (Organelles) and only came into existence .5 billion years ago, they are made up of fungi, animals and plants and some unicellular organisms. A link containing the various parts and organelles the cell as follows…
The Emdosymbiotic Theroy…hmmm what is that!?
Basically this theory first postulated Lynn Margulis in 1967.
Endocytosis=(cyto=cell) is cell eating, that is engulfed by another then digested
Symbiosis=A relationship of mutual benefit or dependence.
Endosymbiosis= cells that are engulfed, but NOT digested….
The hypothesis she proposed:
- mitochondria are results of endocytosis of aerobic bacteria
- chloroplasts are results of endocytosis of photosynthetic bacteria
- both engulfed by large ANAEROBIC bacteria
- this became a mutually beneficial relationship between the two (symbiotic)
The aerobic bacteria would supply the anaerobic bacteria with oxygen and the anaerobic bacteria would ingested food and protect the symbiote. This hypothesis is supported fossils and that chloroplasts and mitochondria posses their own DNA and characteristics of prokaryotic cells.
Link to cell structures >>>(1) http://biology.unm.edu/ccouncil/Biology_124/Summaries/Cell.html
(2)and a little quiz…http://www.biologycorner.com/quiz/qz_cell.html
References : http://www.ncbi.nlm.nih.gov/About/primer/genetics_cell.html