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Lecture 6

BIOL 1201 Lecture 6: Membrane

Biological Sciences
Course Code
BIOL 1201
E William Wischusen

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I. Membrane
1. Cells
1.a. Minimum organization of living matter
1.a.i. Thin outer covering surrounding the cell
1.a.ii. Plasma
1.a.iii. Fluid mosaic model
Phospholipid bilayer with proteins in or on bilayer
Polar head (hydrophilic)
Always moving laterally; 107 times per second
Non -polar tails (hydrophobic)
Mix two cells together, the membrane will fuse together
Cell coat
Glycolipids and glycoproteins
Sugars attached
Cell recognition
1.b. Why do cells have membranes?
1.a.i. Structure
You need something to keep everything inside the cell
1.a.ii. Function
More than a barrier
Maintain concentration of molecules and ions
Create free energy gradients
Orient molecules into functional complexes
1.a.iii. Membrane permeability
Size and shape of molecules
Solubility in lipids
Net electric charge
Other chemical properties
Water is always freely permeable
1.b. Diffusion
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