Term | Definition |
Amphipathic | contain hydrophobic and hydrophilic regions |
Phospholipids | Make up plasma membrane, allows for selective permeability, amphipathic, want to escape from water, head (hydrophilic) and tail (hydrophobic), can move and flip |
Fluid Mosaic | membrane is mostly phospholipids with a "mosaic" of proteins in it |
Lateral Movement | Drifting of phospholipids and proteins within the same layer, happens about 100,000,000 times per second |
Flip-flop movement | Phospholipids and proteins move from one bilayer to the other, RARE, about once per month |
Movement and Temperature | less movement = colder temperature = less fluidity |
Proteins | determine most of the membrane's specific functions |
Peripheral proteins | bound to the surface of the membrane |
Integral proteins | penetrate the hydrophobic core of the membrane, has to be hydrophobic if it is in the hydrophobic membrane core |
Transmembrane proteins | span the entire membrane |
Alpha helix | crosses over the entire membrane |
Functions of membrane proteins | transport, enzymatic activity, signal transduction, cell to cell recognition, intercellular joining, attatchment to cytoskeleton and ECM |
Carbohydrates | allow cell to cell recognition |
Glycolipids (Sugar fats) | sugar is COVALENTLY bonded to lipids |
Glycoproteins (sugar proteins) | sugar is COVALENTLY bonded to proteins |
Cholesterol | inserted between tails of phospholipids, can alter membrane fluidity, serves as buffer for temperature, prevents solidification |
Selective permeability | hydrophobic (nonpolar) molecules pass through hydrophobic bilayer easily, hydrophilic cannot cross easily so they are aided by transport proteins |
Transport proteins | allow passage of hydrophilic substances, all are transmembrane proteins |
Channel protein | provide a hydrophilic channel through the protein which can be gated |
Aquaporins | passage of water through channel proteins |
Ion channels | passage of ions through channel proteins |
Gated channels | open or close in response to a stimulus through channel proteins |
Carrier proteins | binds to a specific molecule and carries the protein from top of the membrane to the bottom and let it go |
Membrane (solute) transport | molecules in solution move randomly causing mixing, 2 types: passive and active |
Concentration | amount of solute in a solvent |
Concentration Gradient | more solute in one part of the solvent than another |
Active transport | energy needed for this transport (specifically ATP) to move solutes against their concentration gradients, raises active potential, requires transport proteins |
Passive transport | no energy needed due to diffusion |
Simple diffusion | transports solutes through membrane which eventually eliminates concentration gradient |
Facilitated Diffusion | transports solutes through transport proteins |
Osmosis | diffusion of water across a membrane, water moves from high to low concentration but solutes move from low to high concentration |
Tonicity | ability of a solution to cause a cell to gain or lose water due to osmosis |
Isotonic solution | equal solutes inside and outside the cells so no change in volume |
Hypertonic Solution | higher solute in solution so water flows out of the cell and the volume of the cell decreases |
Hypotonic solution | higher solute in the cell so water flows into the cell and the volume of the cell increases |
Osmoregulate | when organisms regulate water balance |
Plasmolysis | when a cell membrane pulls away from a cell wall due to hypertonic solutions |
Flaccid cell | happens in an isotonic solution with a cell with a cell wall, no water movement causes cell to become flaccid |
Cotransport | active transport of a solute drives transport of another solution |
Uniport | moves only 1 way (in or out) |
Symport | moves 2 only 1 way (in or out) |
Antiport | one moves in and one moves out |
Bulk transport | requires ATP to move larges molecules in bulk across the membrane via vesicles |
Exocytosis | transports substances OUT of the cell |
Endocytosis | transports substances INTO the cell |