Passive Transport
Transport across the membrane does not require energy. From high to low concentration.
Active Transport
Transport across the membrane that requires energy. From low to high concentration. Requires ATP to counteract diffusion.
Driving Force
Difference in energy across a membrane. Force pushes from higher to lower energy
Chemical, Electrical, and Eectrochemical
What are the 3 driving forces?
Membrane Potential
A difference in electrical potential or voltage across the plasma membrane
Equilibrium Potential
The membrane potential at which the electrical driving force on the ion is equal and opposite to the chemical driving force
Simple Diffusion
Movement of molecules as a result of random thermal motion. Molecules freely cross membrane and net movement is down electrochemical gradient.
Facilitated Diffusion
Molecules bind to specific protein "carriers" or transporters in the membrane that transport them down their electrochemical gradient.
Transporters
Carriers
Diffusion through Ion Channels
Molecules flow through pores in specific protein channels in the membrane down their electrochemical gradient.
Primary Active Transport
Uses ATP directly to provide energy to move molecules against their electrochemical gradient
Secondary Active Transport
One molecule moves passively down its electrochemical gradient to provide energy for another molecule to move up its electrochemical gradient
Cotransport
Cotransported molecules move in the same direction
Countertransport
Countertransported molecules move in opposite directions
Osmosis
Movement of water across a membrane from an area of low concentration solute to an area of high concentration solute, diluting it, until there is equal concentration of solute on both sides of the membrane. Always passive transport.
Osmolarity
Total solute particle concentration of a solution