2.2.3. Membrane I Flashcards
What is bulk flow?
The movement of a solutionfrom one compartment to another due to a pressure gradient
What is simple diffusion?
The movement of a solute through a membrane due to an electrochemical gradient. No transport assistance is involved.
In simple diffusion, how do we know what direction the solute will move?
Whatever gradient exists will push the solute from High to Low (electric: High potential to low potential, concentration: high concentration to low)
What is facilitated diffusion?
The same process as general diffusion, but transport proteins of some kind are needed to help the solute move across the membrane.
What is are some key differences between simple diffusion and simple facilitated diffusion?
(There are three)
1) Specificity: The solute has to fit into the transport protein
2) Competition: Different solutes may fit into the same protein, so they may compete for that space
3) Saturability: Once all protein carriers are engaged, the max rate of diffusion is achieved. Simple diffusion has no max diffusion rate
Does facilitated diffusion require energy?
(Is it an active or passive process?
Facilitated diffusion is still a passive process. No energy, in terms of ATP, are used to enable its action
What is Primary Active Transport?
A transport protein pumps a solute against its energy gradient.
How is primary active transport different than facilitated diffusion?
1) PAT requires energy
2) PAT pumps solutes against their gradient, facilitated diffusion allows for their movement down their gradient
What is Secondary Active Transport?
A combination of facilitated diffusion and active transport.
One solute moves down its gradient using a transport protein, and this same protein uses the energy released from that process to pump another solute against its gradient.
What are the relative concentrations of the following solutes inside and outside of the typical cell?
K+
Na+
Cl-
Organic Anions (A-)
K: Low outside the cell, high in
Na: High outside the cell, low in
Cl: High outside the cell, low in
A: Almost none outside the cell, a LOT in the cell
How permeable is the typical cell to:
K
Na
Cl
Organic Anions (A)
K: High permeability
Na: Low permeability
Cl: Very high permeability
A: Impermeable
How does water and water solubles solutes move into the cell if its bilipid layer is impermeable to water?
There are channels or pores in the cell that are filled with water, allowing for solute and water movement into and out of the cell
Is an actual cell (in general) permeable, impermeable, or semipermeable to ions?
Semipermeable
What are ion leakage channels, and what important role do they play in cells like neurons?
Ion leakage channels are pores in the cell membrane that exhibit selective permeability, allowing ONLY specific ions to pass.
These channels are responsible for the setting the resting potential of neurons
Are leakage channels gated?
No, they are always open