Membrane Transport Flashcards
The membrane transport proteins
- Transporters
- Channels
- transfer solutes across cell membranes
- transfer specific molecular species or a class of molecules
Membrane transport proteins
single-gene mutations
Cystinuria
(carriers or permeases)
– bind, conformational changes
Transporters
form continuous pores
Channels
“downhill” transfer
Passive transport
uncharged molecule
Concentration gradient
charged molecule
membrane potential
“uphill”, against their electrochemical gradients
Active transport
negative insided
Electrical potential
What resembles an enzyme-substrate reactions
Transport of solute in the lipid bilayer
inaccessible-occluded
Intermediate state
Main ways of active transport
- Coupled transport
- ATP-Driven pumps
- Light-or redox- driven pumps
energy stored in concentration gradients
Coupled transport
hydrolysis of ATP
ATP-driven pumps
energy from light
light- or redox-driven pumps
passive transport
Uniporters
transfer of one solute depends on the transport of a second
Coupled transporters
transfer in the same direction
Symporters
transfer in opposite direction
Antiporters
pseudosymmetric
inverted repeats
Three classes of ATP-driven pumps
- P-type pumps
- ABC transporters
- V-type pumps
phosphorylate themselves during pumping cycle
P-type pumps