Transport Flashcards
Where is K+ in high concentration?
intracellular
Where is Na+ in high concentration?
extracellular
how is chemical disequilibrium maintained?
active transport of solutes
membranes act as barriers to prevent solute diffusion
what molecule can freely move across compartments?
water
osmotic equilibrium
when water stops moving across membrane because there is no longer a WP gradient
osmolarity definition
number of particles (molecules) per unit volume (l)
osmolarity equation
moles x n (particle number when dissolved in water)
how do carrier proteins bind transport solutes across membrane?
bind solute on one side of membrane, deliver it to the other side of the membrane via a conformational change in the protein
channel proteins - passive transport
concentration grad. determines direction and rate of travel
no energy needed
simple diffusion/facilitated diffusion
GLUT transporter proteins
glucose transporter
GLUT2 - liver breaks down glycogen store to glucose
primary active transport e.g. sodium potassium pump
uphill movement
e. g. sodium potassium pump
1. 3 sodium bind to cytosilic binding sites
2. protein undergoes conformational change, sodium released outside cell
3. 2 potassium bind to extracellular binding site
4. protein returns to original conformation, potassium released inside cell
secondary active transport
uphill transport of target molecule, coupled to downhill transport of another molecule.
target molecule exploits energy of the molecule moving downhill
downhill gradient often created by ATPase
secondary AT - symporter
1 molecule moves down a conc. grad. (e.g. Na+)
another exploits the energy and moves up a conc. grad. (e.g. glucose)
molecules move in the same direction across the membrane
secondary AT - antiport
energy inherent in downhill transport of one molecule (e.g. Na+) drives the uphill transport of the other molecule (e.g. Ca2+)
the molecules are moving in opposite directions across the membrane
