chapter 3a overview of the cell, and structure of the plasma membrane
TRANSCRIPT
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The cell is the basic structural and functional unit of life
Amoebas are single-cellular
Humans, dogs, trees are multi-cellular
First to observe cells – Robert Hooke in 1600s (1665) (he observed cork)
Anton van Leeuwenhoek observes single cell organisms in pond water 1674
1855 Rudolph Virchow proposed all cells come from existing cells
These discoveries were very important, before ‘cell theory’ which includes all these discoveries, people accepted the theory of spontaneous generation
1. A cell is the basic structural and functional unit of life.
2. The activity of an organism depends on the individual and collective activities of its cells
3. Principle of complementarity, (its function depends on its form)
4. Continuity of life has a cellular basis
All cells are composed chiefly of carbon, hydrogen, nitrogen, oxygen, and trace amounts of several other elements
All cells have the same basic parts and some common functions
Human cells have 3 Main PartsHuman cells have 3 Main Parts
1. Plasma membrane Outer boundary of the cell
2. Cytoplasm Intracellular fluid packed with organelles
3. Nucleus Controls cellular activities
Thin, Double layer (bilayer) of lipids with imbedded, dispersed proteins
Bilayer consists of phospholipids, cholesterol, and glycolipids
Phospholipids have hydrophobic and hydrophilic bipoles
Each phospholipid molecule has a polar ‘head’ that is charged and is hydrophilic
Each phospholipid molecule has a nonpolar ‘tail’ made of 2 fatty acid chains and is hydrophobic
Hydro = water Philic = loving Phobia = hating Polar heads are attracted to water
so they lie on the inner and outer surfaces of the membrane
Nonpolar tails avoid water and line up in the center of the membrane
Plasma membranes also have proteins, glycolipids, glycoproteins, and cholesterol
20% of all membrane lipid is cholesterol
Cells recognize one another by markers made out of glycoproteins called Glycocalyx
Small extensions of the plasma membrane that project from a free, or exposed cell surface
Increases surface area
Most often found on the surface of cells that function in absorption like intestinal and kidney cells
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