Membrane Notes: Ch. 4
KEY WORDS/QUESTIONS / NOTES
Cell Membrane Structure /
A: Integral/transmembrane protein: doorway for molecules to enter cell
B: Peripheral protein: cytoskeleton anchor
C: Phospholipid bilayer: cell boundary, regulates entry to cell
D: Phospholipid head: hydrophilic
E: Phospholipid tails: hydrophobic, can be saturated (membrane more solid b/c pack closer together) or unsaturated (membrane more fluid b/c don’t pack tightly)
F: cholesterol: prevents membrane from solidifying
G: sugars: helps as an ID tag for the cell
H: skip
I: skip
J: cytoskeleton fibers: cell structure
Fluid Mosaic Model / Fluid: all the stuff moves around with in the cell membrane
Mosaic: membrane made up of lots of different parts
Transport Across Membranes / A. Passive Transport
1. Diffusion:
a. particles can move either way across the membrane, just depends on concentration
b. size restrictions:
i. large will not pass (WNP)
ii. charged ions WNP
iii. small will
2. Osmosis: diffusion of water
3. Facilitated Diffusion: some molecules require proteins to help transport through the membrane (down their concentration gradient)
*Types of Facilitated Diffusion Proteins
1. Carrier Proteins: show book animation with carrier proteins
2. Tunnel Proteins: just open tunnels that allow passage
B. Active Tranport
1. Sodium Potassium Pump: image below keys on the fact that for neurons to work (mostly where you would find these pumps) we have to move sodium and potassium to a particular side of the membrane – not necessarily in conjunction with how particles would normally go based on concentration. So, use pumps to get them to the correct side. ATP required to force them through.
2. Bulk Tranport:
a. Endocytosis
Types:
i. Pinocytosis: Cell drinking (General)
ii. Phagocytosis: Cell eating large particles (general)
Receptor Mediated
iii. Endocytosis: More specific in terms of what is being brought in
*Food particles will fuse with lysosomes to digest food material. Food that is needed will difuse out of the particle, the rest/waste will be released via exocytosis
b. Exocytosis