Ch 13 Concepts of Transport Flashcards
The plasma membrane is
selectively permeable
Proteins in plasma membrane act as
ion channels
transporters
pumps
passive diffusion
movement with concentration gradient
active transport
movement against concentration gradient
Na+ is more concentrated in
extracellular
K+ is more concentrated in
intracellular
Ca+ is more concentrated
extracellular
Mg+ is more concentrated in
intracellular
Cl- is more concentrated in
extracellular
intracellular pH is
7.0
extracellular pH is
7.4
transport via simple diffusion and facilitated diffusion requires no
energy
transport via active transport requires
energy
protein transport requires a____________ change of the protein
conformational
If two substances are in solution together they will not interfere with diffusion of eachother. True or False
True
Net movement depends on (diffusion)
concentration gradient
particle size
permeability of compound in trying to pass barrier
simple/passive diffusion uses
no carrier protein interaction
can use pores or channels
facilitated diffusion uses
a carrier protein
binding occurs
Lipid diffusion through lipid bilayer
O, N, CO2, and alcohols highly lipid soluble
rate of diffusion dependent on degree of lipid solubility
Lipid insoluble compounds and water through protein channels
pore channels for small molecules
pore diameter and charge on amino acids determines selectivity of passge
Two types of gates used in channel protein
voltage gated channels=electrical
ligand-gated channels=chemical
potassium channels selectively filter for
K+
Sodium channels are lined with amino acids that are highly
negative
(voltage gating) sodium and potassium channels open when the inside of cell becomes
positively charged
(chemical gating) binding a molecule may
open or close the gate
Binding affinity in carrier proteins is measured by
Km
If transporters are saturated they are said to be
maxed out (Vmax)
Km
=solute concentration that will give 1/2Vmax
Osmosis
semipermeable membrane allows movement of H2O but not solutes
moves from high to low via aquaporins
goal is to equalize concentration of solutes
Hydrostatic pressure
prussure applied to stop flow of water from high to low
Isotonic
pressure same on inside and outside of cell
Hypotonic
movement of water into cell
increases cell volume
pressure greater in cytosol
Hypertonic
movement of water out of cell
cell will shrink
pressure greater outside of cell
