Transport membrane Flashcards
most abundant lipid in the plasma membrane
phospholipids
what are amphipathic molecules
contain both hydrophilic and hydrophobic regions
what part of the phospholipid is hydrophilic
head
protein bound to the surface of the membrane
peripheral
protein that penetrates the hydrophobic core
integral protein
integral proteins that span the membrane
transmembrane protein
receptors for HIV
CD4 and CCR5
facilitate the passage of water
aquaporin
bind to molecules and change shape to shuttle them across the membrane
carrier proteins
movement of molecules (solute) from an area of higher concentration to an area of lower concentration without any energy investment
diffusion
diffusion of water
osmosis
ability of a surrounding solution to cause a cell to gain or lose water
tonicity
solute concentration outside = inside, no net movement of water
isotonic
solute concentration outside > inside, cell loses water, cell becomes shriveled
hypertonic solution
solute concentration outside < inside, cell gains water, cell may swell or burst
hypotonic solution
control of solute concentration and water balance
osmoregulation
provide corridors to allow specific molecules to cross the membrane
channel proteins
moves substances against their concentration gradient
active transport
optimum concentration of Na and K outside and inside the cell
outside: high Na, low K
inside: low Na, high K
sodium potassium pump action
release 3 sodium ions outside, takes in 2 potassium ions
membrane potential
voltage difference across a membrane
transport protein that generates voltage across the membrane
electrogenic pump
electrogenic pump in plants, fungi and bacteria
proton pump
occurs when active transport of a solute indirectly drives transport of other substances
cotransport
coupled transport protein for same direction
symport
coupled transport protein for opposite direction
antiport
movement of macromolecules into and out of the cell
bulk transport
phagocytosis vs pinocytosis
phagocytosis - cellular eating
pinocytosis - cellular drinking
binding of ligands to receptor triggers vesicle formation
receptor-mediated endocytosis
any molecules that binds specifically to a receptor site of another molecule
ligand