cell membrane

• major structural components of FMM: phospholipid layer, cholesterol, and proteins
• phospholipids are a 3 carbon molecule with, phospholipids are bound to 2 carbons and the 3rd is a phosphate group (charged)
• double bonds make unsaturated fatty acids difficult to pack together, increasing fluidity
• double bonds in fatty acids introduces a kink so it cant pack together as tightly, increasing fluidity
• interaction between cholesterol and hydrophobic tails tightens the packing of phospholipids in the bilayer, increasing membrane integrity
• integral proteins interact with the hydrophobic core are imbedded in the bilayer, these are mostly transmembrane
• the transmembrane proteins cross the membrane and produde into both aqueus environments
• peripheral proteins are associated with one face of the bilayer, and interact with integral membrane proteins or polar head group, but not hydrophobic core
• membrane proteins move laterally unless anchored
• receptors transmit signals by transducing them
• non-polar molecules (lipids) readily diffuse across the bilayer as they are hydrophobic
• polar molecules and ions have difficulty diffusing across the bilayer as they are hydrophilic
• highly hydrophilic molecules only pass through membrane with channel proteins
• simple diffusion is used for o2 and co2, lipids, lipid solouble molecules and water
• facilitated diffusion is for large polar molecules and ions, no energy is required
• channels are for ions
• carriers are for polar molecules like glucose
• channel proteins provider a hydrophilic passageway for passive diffusion
• carrier proteins bind the solute, that causes a conformational change, solute is released on other side
• the sodium potassium pump lets 3 sodium out for 2 potassiums in
• endocytosis imports large molecules in vesicles formed by membrane folding
• exocytosis happens when vesicles fuse with plasma membrane to release contents outside of cell
• phagocytosis is the invagination to produce vesicles for bacterial cells
• pinocytosis is for aqueus solutions
• receptor mediated endocytosis is the binding in recogntion with a receptor, and then the invagination to form a coated vesicle
• if RBC are in a hypotonic solution they are lysed
• if RBC are in an isotonic solution, they remain normal
• if a RBC is in a hypertonic solution, it is shrivelled due to net movement out of the cell
• phospholipids are amphipathic