Cell
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This article is only a brief description of the subject, and is not intended to give a full explanation.
Check out the "see also" or "references" sections, or Wikipedia's article for more detail.
- This article is mainly about cell in Biology. As such, we are not talking about electrochemical cells, prison cells, terrorist cells, or the cell in a spreadsheet.
The cell is the smallest functional living unit. All organisms consist of at least one cell.
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[edit] Prokaryotes
<joke>Prokaryotes are organisms in favor of karyotes.</joke>
In reality, prokaryotes are cells which do not have a nucleus. They also tend to lack other organelles, and are smaller than eukaryotes. Bacteria are prokaryotes.
[edit] Eukaryotes
Endosymbiotic theory, originating at the beginning of the 20th century, but maturing under the study of biologist Lynn Margulis, is the theory that eukaryotic cells (cells differing from bacteria in their level of complexity and presence of organelles), evolved from prokaryotic cells via the process of endosymbiosis. To oversimplify, prokaryotic cells may have phagocytosed other prokaryotes, and benefited from the energy-producing properties of them. This relationship eventually became permanent, leading to structures now called chloroplasts and mitochondria. In other words, some of the organelles inside the cells in your body were once one-celled parasites that invaded other cells. Through the process of evolution, over millions of years, these parasitic cells lost the ability to live outside their host and became essential to the function and survival of the cell.
[edit] Evolution
The evolution of the cell is one of the more contested and intriguing aspects of evolutionary theory. Once cellular life has formed, natural selection and all the processes we see today are fairly self-evidence and more than capable of working up to complex life. However, getting to the stage where a cell is formed is a slightly more difficult, or at least more time consuming.
The high degree of complexity in the cell (even though it's just organised chemistry) is one of the many things cited as evidence of intelligent design. The movie Expelled used it as a key point in an extended CG sequence showing the inner workings of the cell in order to inspire incredulity in its audience.[1]
