cell membrane + transport BIO12

cell membrane function

composed of a phospholipid bilayer that separates the cell from the environment (an enclosure that is different)

word for when phospholipids have a polar and non polar end

amphipathic

charged/polar substances enter with a..

protein carrier

extremely small molecules that dont need protein carrier

O2,CO2,H2O, steroid hromones

membrane protein function

carrier, channel fpr transport, enzymes, receptore for hormones, cell-cell recognition

glycoprotein

uses cell to cell recognition- carbohydrate chain extend outside of cell (unique to everyone)

fluid mosaic model is used to describe

cell membranes: proteins move in in the cell membrane, but transmembrane proteins are stuck

cholesterol is found in membranes for..

increasing fluidity at low temp, preventing us from turning into cold block of butter

2 types of membrane proteins

peripheral and intergral

peripheral protein:

bound to surface of membrane, often bounded to intergral proteins 

reception of signals, function like enzymes

integral protein:

AKA transmembrane proteins: stuck in the bilayer, transports across membrane. may contain a hydrophillic channel for allowing polar/charged molecules through

what is selectively permeable

allows certain things to pass

membrane selection depends on

size, available carrier protein, polariyt/charge

4 types of celular transport

simple diffusion, osmosis, faciltated transport, active transport

concentration gradient

concentration that determines movement of molecules HIGH TO LOW

which require carriers

sugars, polar molecules, ions

what doesnt require carrier

non-polar (fats), small molecules (CO2, O2,

diffusion

movement of molecules in solution forom high to low concentratoin along concentration gradient (no ATP)

faciliated transport

carrier proteins assist diffusion accross membrane. diff types of protein carriers unique to molecule/ion (no ATP)

faciliated transport 4 steps

1temporary bind w carrier

2cause portein to change formation

3substances passes thru carrier and leaves canal

4carrier regains orginginal concentraion

faxtors that affect diffusion rates

[ ], temp, pressure, more carrier proteins (more doors!)

explain osmosis

water/solvent diffusion respomse to concentration gradient (no ATP)

mother nature likes same concentrations. solute dont move, solvent will to control [ ]

osmotic define

force applied by “osmosing”

isotonic

2 solutions with the same concentration

hypotonic

“weaker” less concentrated one compared to the other

hypertonic

“stronger” more concentrated one to the other

active transport

active- against concentration gradient to maintain needed concentration (low to high)

active transport

specific protein carriers, energy (ATP)

energy pump

protein carrier that pumps! ATP phosphorylates to provide energy for protein carrier (ex. let Na+ out, K+ in)

phosphorylation and DEphosphorylation

(ATP=ADP+P) conformational change in protein.

DE: return original conformation

big subtances enter/exit by:

vesicular transport: exocytosis, endocytosis need ATP

exo

in (drinking, etaing)

endo

out (secreting)