Cell Membrane & Transport Fluid mosaic model - Lipids, proteins & carbohydrates Membrane...
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Transcript of Cell Membrane & Transport Fluid mosaic model - Lipids, proteins & carbohydrates Membrane...
Cell Cell Membrane & Membrane &
TransportTransport
Fluid mosaic model - Lipids, proteins & carbohydrates
Membrane trafficking - Passive Transport
- Active Transport
- Bulk Transport
Plasma Membrane - Plasma Membrane - Phospholipid BilayerPhospholipid Bilayer
Composition: - lipids, proteins & carbohydrates
Phospholipids, cholesterol & glycolipids - head: contains a polar phosphate group (hydrophilic) - tails: 2 nonpolar hydrocarbon fatty acid (hydrophobic)
Functions: - protection - controls traffic - selective permeable - anchoring/fusion
Fluid-Mosaic Model of Plasma MembraneFluid-Mosaic Model of Plasma Membrane
http://telstar.ote.cmu.edu/biology/downloads/membranes/index.html
Functions of Membrane Functions of Membrane ProteinsProteins
Membrane
Trafficking
Passive Passive TransportTransport
Simple diffusion: mov’t of molecules from a region
of high[ ] low
Concentration gradient: difference in [ ] b/t two regions - substances always move in the direction of the [ ] gradient
Membrane permeability of lipid bilayer- nonpolar vs polar molecules
O2 & CO2 can cross a lipid bilayer without help from membrane proteins – what properties allow this to
occur?
Diffusion PropertiesDiffusion Properties
Characteristics: not carrier-mediated, [ ] gradient & passive
Definitions: solution, solvent & solutes
Factors that influence rate of diffusion:
– temperature
– state of solvent
– size of molecules
– diffusion gradient
– membrane structure
So what So what is is solubilitsolubility?y?
OsmosisOsmosis
Diffusion of H2O across a selectively permeable membrane from a region of solute [ ] to a solute [ ] establish equilibrium
Osmotic pressure: pressure applied to the cell membrane from flow of H2O during osmosis -- # of particles in solution
Tonicity: the ability of a solution to cause a cell to gain or lose water
- isotonic, hypotonic & hypertonic
Facilitated Diffusion: Passive Facilitated Diffusion: Passive Transport Aided by ProteinsTransport Aided by Proteins
Carrier proteins
Primary active transport: movement of solutes against [ ] gradient biological membrane
- energy dependent
Na+/K+-ATPase pump:– resting membrane potential– osmotic balance– drives other pumps
Electrogenic pump
Active Active TransportTransport
+ + + + + + + + + + + + + +
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ATP
http://highered.mcgraw-hill.com/olc/dl/120068/bio03.swf