Cell
This is an old revision of this page, as edited by Philip J. Rayment (talk | contribs) at 09:55, December 31, 2007. It may differ significantly from current revision.
The cell is the smallest unit of life capable of independently reproducing itself. It is a small, watery, compartment filled with chemical-based machinery and a complete copy of the organism's genome.
There are two main types of cells: prokaryotic[1] cells, which lack a nucleus, and eukaryotic[1] cells, with a nucleus separated from cytoplasm by a nuclear membrane.
A bacterium is a simple cell without a nucleus to protect its genetic information.
A virus requires structures in a cell's cytoplasm to assemble copies of itself.
There is no consensus on the exact number of cells in a human body, though the number ranges from 10 to 100 trillion cells.[2]