| A | B |
|---|
| selectively permeable | a membrane that allows some substances to cross more easily than others |
| amphipathic molecules | molecules that have both hydrophobic regions and hydrophilic regions |
| peripheral proteins | proteins not embedded in the lipid bilayer |
| integral proteins | membrane proteins that penetrate the hydrophobic core of the lipid bilayer, often completely spanning the membrane |
| Cell-cell recognition | the ability of a cell to distinguish one type of neighboring cell from another |
| diffusion | the tendency of molecules of any substance to spread out in the available space |
| passive transport | the diffusion of a substance across a biological membrane in which no energy from the cell is required to make it happen |
| hypertonic | the solution with the higher concentration of solutes |
| hypotonic | the solution with the lower concentration of solutes |
| isotonic | solutions with equal solute concentrations |
| osmosis | the diffusion of water across a selectively permeable membrane |
| plasmolysis | as the plant cell loses water, its volume shrinks and the plasma membrane pulls away from the wall |
| facilitated diffusion | the passive movement of molecules down its concentration gradient via a transport protein |
| aquaporins | water channel proteins |
| gated channels | channel proteins that open or close depending on the presence or absence of a physical or chemical stimulus |
| active transport | movement of substance through a membrane that requires the cell to expend its own metabolic energy |
| electrogenic pumps | special transport proteins that generate the voltage gradients across a membrane |
| endocytosis | when a cell brings in macromolecules and particulate matter by forming new vesicles from the plasma membrane |
| phagocytosis | "cellular eating" |
| pinocytosis | "cellular drinking" |
| hypercholesterolemia | an inherited disease in which the LDL receptors are defective, leading to an accumulation of LDL and cholesterol in the blood |
