2 Green

History

1855 - C. Naegeli and C. Cramer describe cell membrane as barrier essential to explain osmosis in plant cells

History (Continued)

1972 – The fluid mosaic model was created by S. J. Singer and Garth Nicolson, and stated that cell membranes can be considered as a two-dimensional liquid where all lipid and protein molecules diffuse freely

Structure

Structure (Continued)Primarily lipids and proteinsUnsaturated/Saturated changes

rigidityPolar, usually rejects ions,

hormones, ion channelsProteins stretch through,

integral proteinsCellular

communication/recognition

LocationIn an animal cell,

outermost layer

In a plant cell, just inside cell wall

Present in both

FunctionThe lipid bilayer provides rigidity, maintaining

the shape of the cell

Materials that can be dissolved in water pass through the membrane via osmosis

Other materials rely on ion channels to move through

InteractionsWorks with the cytoskeleton, structure

Ribosomes produce proteins that are then inserted into a lipid bilayer of their own by the endoplasmic reticulum and transported to the cell membrane by a vesicle, where both are absorbed into the cell membrane

Effi ciency and Effectiveness

Seperates the cytoplasm from the extracellular environment

Allows materials to be transported across it

If the cell membrane were not there, it wouldn’t make sense to call it a cell, more of a soup that flows around mixing with its surroundings and spreading out.

Sourceshttp://www.usoe.k12.ut.us/CURR/science/sciber

00/7th/cells/sciber/membrane.htm June 15, 2000

http://www.cellsalive.com/cells/cell_model.htm, 2006

http://en.wikipedia.org/wiki/Cell_membrane, 14 November 2009

http://www.whatislife.com/education/fact/history_table.html

, November 8, 2009