Term
| What are the 3 factors that govern solute transport across a membrane? |
|
Definition
1. Eletrochemical gradient (driving force)
2. Permeability of the membrane to the solute
3. The solutes pathway (passive, active, coupled, enzymatic reaction) |
|
|
Term
| What are the differences between active and passive transport? |
|
Definition
Passive - Movement down an electrochemical gradient, no energy input required
Active - movement up an electrochemical gradient, energy input required |
|
|
Term
| What is simple diffusion? |
|
Definition
| Membrane soluble solutes diffuse through the bilayer |
|
|
Term
|
Definition
| Diffusion through a transmembrane channel that is always open |
|
|
Term
| What is channel transport? |
|
Definition
| Diffusion through a transmembrane channel that is NOT always open, it is gated and opens under certain circumstances |
|
|
Term
| What is carrier mediated transport? |
|
Definition
Transport across a membrane by a transmembrane carrier that goes through multiple conformational changes that allow it to move solutes into a cell
Note: Differs from channel in that channels allow thousand solutes per cycle where carriers only allow one to several solutes per cycle to be transporter |
|
|
Term
| What are the 4 types of simple diffusion? |
|
Definition
1. Simple diffusion
2. Pore diffusion
3. Channel diffusion
4. Carrier mediated diffusion |
|
|
Term
| What is primary active transport? |
|
Definition
| Transport up an electrogradient by coupling the movement to a favorable, exergonic energy source such as ATP hydrolysis |
|
|
Term
| What is secondary active transport? What are the two types? |
|
Definition
Movement up an electrochemical gradient where the energy source for movement comes from coupling the uphill movement of one solute to the downhill transport of another such that the net free energy change is exergonic.
The two types are cotransport and counter-transporters. Cotransporters move both solutes in the same direction, whereas counter transporters move in opposite direction. |
|
|
Term
| Explain how transporters can be used to regulate cell size in response to changes in osmolarity |
|
Definition
| When a cell shrinks or swells, it activates ion transporters to move ions into or out of the cell. This alters the osmolality of the cell, causing water to enter the cell (in the case of shrinkage) or exit the cell (in the case of swelling) to regulate the cell back to its normal size. |
|
|
