DEFINITIONS
•Phospholipid= A molecule with hydrophilic phosphate &
hydrophobic lipid regions
•Phospholipid bilayer(=doppio strato)= A double layer of
phospholipids that makes up a plasma membrane
•Integral Protein= A protein embedded in the lipid bilayer of a
membrane. e.g. protein channels, or pumps.
•Peripheral Protein= A protein attached to the surface of a
membrane
•Cholesterol= A steroid present in the plasma membranes of
animal cells. It affects membrane fluidity.
•Selectively Permeable= Some substances pass through the
membrane but not others.
•Diffusion= The passive movement of molecules from an area of
high concentration to an area of lower concentration.
•Osmosis= The passive movement of water through a selectively
permeable membrane
•Concentration Gradient= A difference in the concentration of a
substance across a space
•Facilitated Diffusion= Passive transport of ions or polar
molecules across a membrane by protein channels
•Active Transport= Movement of a substance through a cell
membrane against the concentration gradient; requires energy.
•Sodium-Potassium Pump= A protein that uses ATP to transport
ions against the concentration gradient by active transport.
