Membrane Transport Flashcards
Passive processes of transport
osmosis, facilitated diffusion, diffusion, bulk filtration
Functions of the Plasma Membrane
Physical Barrier, Gateway for exchange, Communication, Site of Attachment
other cells, extracellular and intracellular proteins
What part of the plasma membrane aids in communication?
receptors
Simple Diffusion
the random motion of molecules in solution (results in the spread of molecules from areas if high concentration to areas of low concentration
What does Jnet mean in Fick’s Law of Diffusion
Net Flux
What does the Fick’s Law of Diffusion mean in words
Flux equals the negative of the product of solute diffusion coefficient (Ds) and solute concentration gradient (dCs/dx)
What factors increase the rate of diffusion?
temp, area, membrane permeability, and lipid solubility
What decreases the rate of diffusion?
membrane thickness and molecular size
Why is the equation for Fick’s Law of Diffusion negative?
up= outside the cell
down= inside the cell
negative from going up to down
fluxing in
A decrease in the concentration gradient will.. increase or decrease flux?
decrease
What are the major things that are going to affect the rate of diffusion?
membrane permeability and concentration gradient
In Einstein’s Solution of Fick’s eq, what is D
diffusional coefficient
In Einstein’s Solution of Fick’s eq, what is d
distance
Osmosis in respect to solutes
low solute concentration to high solute concentration
bulk filtration
the concentrated movement of large groups of molecules, often including water (often in response to pressure)
What are the active processes of transport?
protein-based transporters and pumps
Channels
usually for ions; passive, classical “facilitated diffusion”
Carriers
Doorman mechanism; uniport, symport, antiport; may be active or passive
Pumps
typically for ions; active: require direct energy usage (ATP)
Ion Channels
membrane proteins that act as a passive conduit for ions through the membrane
When open ion channels permit __________ ________ of ions
passive diffusion
Channelopathies
Diseases or disorders associated with ion channel dysfunction
Are channels or transporter faster?
channels (transporters are not designed for speed) (just like ur mom)
Alternating access model
carrier proteins cycle between multiple conformations in which a solute binding site is accessible on one side of the membrane or the other
With carrier proteins, is there ever a open channel all the way through the membrane?
no.
What is secondary active transport?
utilizes energy stored in a pre-existing concentration gradient
What happens in the Na/K pump
3 Na out, 2 K in
