TRANSPORT ACROSS MEMBRANE Flashcards
Cell surface membrane
Membrane is semi selectively permeable
Fluid-mosaic model
Mosaic = protein molecules are unevenly distributed
Model= based on experiments
Fluid = bilayer is cinstantly movimt around relative to one another
Function of phospholipids
Allow lipid soluble substances to enter and leave cell
Prevent water soluble substances eneter and leave cell
Make membrane flexible & self-sealing
Function of cholestrol
Decreases permeabilityand increases the stability of membrane
More cholesterol = less fluidity of membrane
Channel protein function
Allows specific charged ions or small molecules to move across membrane by facilitated diffusion
Only transport complementary molecules
Carrier proteins function
Allows transport of ions/ polar molecules and large molecules
Receptor proteins
Specofic receptors for complementary molecules
Glycoprotein function
Glycoprotein are composed of carbohydrate and protein
Act as antigen
Simple diffusion
Net movement of molecules from an areabof higher conventration to a lower concentration across a partially permeable membrane
Factor affecting rate of diffusion
Temperature
Surface area
Concentration gradient
Diffusion distance
Osmosis
Net movement of water molecules from higher water potential to a lower water potentiak through a selectively permeable membrane
Active transport
Against voncentration gradient
From low concentration to a high concentration
Using carrier proteins
Requieres ATP
