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1.3 IB Bio

Membrane Structure

Fluid Mosaic Model N/A
Davson-Denielli Model -Cell membranes consist of a phospholipid bilayer coated in protein -Explained how a 10nm thick membrane could be an effective barrier against substances -Two dark bands with lighter band in between -Proteins dark in electron micrograph
Freeze etched electron micro graphs -Rapid freezing and fracturing of cells, occurs in weak regions (occurred through middle of membrane)
Structure of membrane proteins -Structure of membrane proteins; are varied and globular in shape (not likely to form a continuous layer) -Some proteins have hydrophobic sections, they are attracted to hydrocarbon tails in center of membrane
Fluorescent antibody tagging -Antibodies will attach to particular proteins -Antibodies are fluorescently labeled green or red -One cell labeled green and another red (fused together with electric discharge) -After time red and green were evenly distributed throughout larger cell
Phospholipids form bilayers -Hydrophobic fatty acid tails repel water and are attracted to each other -Hydrophilic phosphate heads attract water and orient to face water (extra and intracellular fluid)
Membrane protein diversity -Parts of proteins that face outside the membrane (into the cell or towards the extra cellular fluid) are polar -Parts of proteins that face the hydrocarbon are non-polar -Some proteins will be associated with polysaccharides (glycoproteins/antlers)
Hormone binding sites -Immobilized enzymes -Cell adhesion -Cell to cell communication -Channels for passive transport -Pumps for active transport
Cholesterol in animal cell membranes and mammalian membranes -Reduces membrane fluidity by reducing phospholipid movement at moderate temps but it also hinders solidification at low temps -Also helps prevent some ions such as sodium from crossing the membrane because it is hydrophobic
Created by: averyschwarz