BIO 185 Lecture Notes - Lecture 2: Fluid Mosaic Model, Lipid Bilayer, Membrane Protein
Document Summary
Phospholipids = 2 fatty acids + hydrophilic/polar head (glycerol + polar phosphate group. Cell membrane is phospholipid bilayer- membrane is gatekeeper of cell. Hydrophilic heads in contact with surrounding solution and cell cytoplasm, hydrophobic tails facing inwards. Cholesterol is another hydrophobic component of eukaryotic cell membranes. Has hydroxyl group, tiny polar head group, and rigid hydrophobic tail. Can fill gaps between phospholipids and thus stabilizes the bilayer. Without cholesterol, membranes would be too fluid and too permeable to some molecules. Also prevents fatty acid tails from coming together and crystallizing when it"s cold. Thus, it adds fluidity too which is important for endo/exocytosis. Double bonds in cholesterol cause bends that also add fluidity. Proteins are essential and embedded in membranes. The more metabolic and transport functions a membrane has, the more proteins it has. Fluid mosaic model - phospholipid bilayer, proteins with hydrophilic and hydrophobic regions, glycoproteins (sugars covalently bonded to protein), integral and peripheral proteins, carbohydrates.
