Bio Vocab: Membranes

Passive transport

movement of particles down the concentration gradient without using energy

Simple diffusion

small nonpolar particles pass directly through the phospholipid bilayer

Facilitated diffusion

particles pass through protein channels or carriers

Aquaporins

channel proteins that allow rapid movement of water across membranes

Osmosis

passive movement of water toward higher solute concentration

Concentration gradient

the difference in concentration of a substance between two areas

Semipermeable

allowing some substances to pass through while blocking others

Active transport

movement of particles against the concentration gradient using ATP

Endocytosis

membrane folds inward to bring material into the cell in vesicles

Phagocytosis

endocytosis of large solid particles

Pinocytosis

endocytosis of dissolved substances and liquids

Exocytosis

vesicles fuse with the membrane to release material out of the cell

Secretion

release of useful substances by exocytosis

Excretion

removal of metabolic waste products

Bilayer

two layers of phospholipids

Amphipathic

having both hydrophilic and hydrophobic parts

Hydrophilic

attracted to water

Hydrophobic

repelled by water

Cholesterol

lipid that stabilizes membrane fluidity

Integral protein

embedded in the hydrophobic core of the membrane

Monotopic protein

protein attached to one side of the membrane

Polytopic protein

protein that crosses the membrane multiple times

Peripheral protein

attached to the membrane surface

Glycocalyx

sugary coating on glycoproteins and glycolipids

Glycolipid

lipid with a carbohydrate chain for cell recognition

Glycoprotein

protein with a carbohydrate chain for recognition