“…For every living organism is, or at some time has been, a cell.” E.B. Wilson, 1925
Why Study Cell Biology?
Cells are Us
A person contains about 100 trillion cells. That’s 100,000,000,000,000 or 1 x 1014 cells.
There are about 1,000 different cell types in humans
Cells are tiny, measuring on average about 0.002 cm (20 um) across. That’s about 1250 cells per inch.
nerve cell
Red and white blood cells
How big are cells?• Bacteria e.g. Eschericia coli (aka E.coli)
• Size=1 µm by 3 µm (one millionth of meter!)
The Cell Theory (1838-1839)**
All organisms are composed of one or more cells.
Cells are the smallest living things.
Cells arise only by division of previously existing cells.
Schleiden
Schwann
http://www.youtube.com/watch?v=gEwzDydciWc&feature=related
The Nucleus Think of the nucleus as the cell’s control center.
Two meters of human DNA fits into a nucleus that’s 0.000005 meters across.
• http://www.youtube.com/watch?v=KxTYyNEbVU4&feature=related
http://www.youtube.com/watch?v=7pR7TNzJ_pA&feature=related
http://www.youtube.com/watch?v=_k78AWnDaqA