1 2 Membrane Transport: Passive and Active Flashcards
___, like ___ and ___ are highly lipid soluble and easily pass though the PM
gasses like oxygen and carbon dioxide
lipid bilayer is made of
phospholipids with hydrophlic heads and hydrophobic fatty acid tails (the lipid part is in the middle)
e.g. of intrinsic membrane proteins
ion channels, water channels, transporters, hormone receptors, cell surface antigens
intrinsic membrane proteins have _____ amino acid regions which are tucked within the alpha helix
hydrophlic
these are tucked inside since they are running through a hydrophobic region (the membrane)
movement in the bilayer (2 examples)
axial rotation
lateral diffusion
e.g. extrinsic/peripheral proteins
proteins of the cytoskeleton
extrinsic protein features
do not span the membrane
attachment occurs via ionic interactions to membrane phospholipids or intrinsic proteins
carbohydrates are on the ___ surface of the membrane
extracellular
role of monosaccharides on the PM
cell recognition/determining receptor specificity
passive transport: definition, examples
substance is transported down its electrochemical gradient and no energy is required
simple diffusion, facilitated diffusion
active transport: definition, examples
substance is transported against its electrochemical gradient and requires energy (ATP)
primary active transport, secondary active transport
all transport except for ____ needs a carrier molecule
simple diffusion
3 characteristics of carrier mediated transport
saturation
stereospecificity
competition
saturation
limited number of binding sites on carrier proteins (transport maximum or Tm)
which type of diffusion does not care about stereospecificity
simple diffusion
competition
structurally similar solutes compete for the same site
is simple diffusion saturable?
no
Km =
solute concentration which gives half the maximal transport rate
simple diffusion
non-carrier mediated transport down an electrochemical gradient
FLUX, J
the rate of net diffusion of solute molecules
the amount of solute moving across a unit area of membrane per unit of time
flux depends on 5 things
concentration gradient across the membrane thickness of the membrane lipid solubility of the solute diffusion coefficient permeability of a solute
oil water partition coefficient (K)
oil / water
the higher it is, the greater the lipid solubility
diffusion coefficient (D)
the larger the molecule and more viscous the medium, the lower the D
permeability
P = KD / membrane thickness