3.3 Passive Processes Flashcards
collisions cause molecules to move down or with their concentration gradient
Diffusion
the difference in the concentration of a particular substance between two different areas
Concentration gradient
nonpolar and lipid soluble substances diffuse directly through the lipid bilayer
ex. oxygen, carbon dioxide, fat-soluble vitamins
Simple diffusion
transport specific polar molecules too large for channels; binding of substrate causes shape change in carrier then passage across membrane
ex. sugars, amino acids
Carrier-mediated facilitated diffusions
aqueous channels formed by transmembrane proteins
ex. ions, water
Channel-mediated facilitated diffusions
channels that are always open
Leakage channels
channels that are controlled by chemical or electrical signals
Gated channels
the diffusion of a solvent; such as water, through a selectively permeable membrane; occurs whenever the water concentration differs on the two sides of a membrane
Osmosis
water-specific channels single water molecules move freely through
Aquaporins
back pressure exerted by water against the membrane
Hydrostatic pressure
the tendency of water to move into the cell by osmosis
Osmotic pressure
ability of solution to alter cell’s water volume
Tonicity
solution with the same non-penetrating solute concentration as cytosol
Isotonic
solution with higher non-penetrating solute concentration than cytosol; crenate
Hypertonic
solution with lower non-penetration solute concentration than cytosol
Hypotonic
