Lecture 14

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8 Nov 2010
10-11-07 10:40 PM
Lecture 14 Notes
What are requirements for life?
1. Supply of replicators- self reproducing molecules
2. Replicator copying must be subject to error
3. Supply of free energy for metabolism/ growth/ reproduction/ movement
4. Partial isolation from external environment
Why are membranes so important?
Separate cell interior from external environment
Enclose cells and organelles inside cells
Responsible for selective permeability
Biological membranes are selectively permeable- some thing’s are
allowed into the cell and some arent
held by weak hydrophobic forces- actually really strong though because
they are in such large numbers
Head- polar- carries a charge- wants to interact with water- therefore
Tail- non polar- uncharged- doesnt like water- hydrophobic
Amphipathic- carries both opposite characteristics
Lipids maintain phospholipid bilayer spontaneously
Lateral movement occurs at about 10 billion times per second
Two types of membrane proteins
Peripheral- on 1 side of the membrane only
Integral (transmembrane)
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