EXSS 256 Exam 1 | Comprehensive Exam Prep | Practice Questions, Answers & Detailed Rationales
membrane permeability. plasma membranes are selectively permeable. the lipid bilayer is always permeable
to small, nonpolar, uncharged molecules. The membrane is impermeable to ions or
charged molecules. transmembrane proteins act as channels or transporters to
increase membrane permeability. macromolecules are only able to pass through by
vesicular transport.
concentration gradient the difference in the concentration of a chemical between one side of the membrane
and the other.
O2 and Na ions have a greater concentration outside the cell.
CO2 and K ions have a greater concentration inside the cell.
electrical gradient difference in concentration of ions between one side of the plasma membrane and
the other. sets up membrane potential.
electrochemical gradients electrical and concentration gradients together.
passive transport simple diffusion, facilitated diffusion, and osmosis
active transport primary active transport, secondary active transport, and vesicular transport.
simple diffusion random mixing of particles in a solution as a result of the kinetic energy of those
particles. both the solvent and solute can diffuse. movement from high to low
concentrations.
what increases the rate of diffusion? steeper gradient, higher temperature, smaller particle, greater surface area, and
smaller diffusion distance.
diffusion through the lipid bilayer nonpolar, hydrophobic molecules. important for gas exchange, nutrient absorption,
and waste excretion.
leakage channel gates alternate from open to closed (Na and K)
voltage-gated channels open in response to a change in membrane potential (Na and K)
ligand-gated channels open and close in response to a chemical stimuli like hormones, neurotransmitters,
or other ions.
facilitated diffusion solute binds to a specific transporter protein and the transporter undergoes
conformational change. the solute then moves across the membrane and is
released on the other side only down its concentration gradient.
glucose, urea, fructose, galactose, and vitamins.
osmosis the net movement of a solvent through a selectively permeable membrane from an
area of high concentration to an area of low concentration.
, EXSS 256 Exam 1 | Comprehensive Exam Prep | Practice Questions, Answers & Detailed Rationales
hydrostatic pressure pressure that the water column exerts
osmotic pressure pressure a solution exerts when its particles are not permeable to the membrane;
proportional to the concentration of solute particles that cannot cross the
membrane.
tonicity how the osmolarity of a solution affects the cell volume
hypertonic tonicity of the solution is higher than the tonicity of the cell
hypotonic tonicity of the solution is lower than the tonicity of the cell
isotonic tonicity of the solution is the same as the tonicity of the cell.
primary active transport energy derived from ATP changes the shape of a transporter protein which pumps a
substance across a plasma membrane against its concentration gradient. most
prevalent is Na/K pump. requires 40% cellular ATP, operates continually, low Na and
high K in cytosol.
secondary active transport energy stored in Na or H ion concentration gradient used to drive other substances
against their own concentration gradients. creates ion gradients. symporters move
substrates in the same direction and antiporters move substrates in opposite
directions.
vesicle small membranous sac formed by budding off from an existing membrane.
endocytosis bringing something into the cell. phagocytosis is a cell eating and pinocytosis is a
cell drinking.
exocytosis release something from the cell.
metabolism the sum of all chemical reactions in the body.
catabolism breakdown; exergonic
anabolism building; endergonic
oxidation removal of electrons from an atom or molecule
membrane permeability. plasma membranes are selectively permeable. the lipid bilayer is always permeable
to small, nonpolar, uncharged molecules. The membrane is impermeable to ions or
charged molecules. transmembrane proteins act as channels or transporters to
increase membrane permeability. macromolecules are only able to pass through by
vesicular transport.
concentration gradient the difference in the concentration of a chemical between one side of the membrane
and the other.
O2 and Na ions have a greater concentration outside the cell.
CO2 and K ions have a greater concentration inside the cell.
electrical gradient difference in concentration of ions between one side of the plasma membrane and
the other. sets up membrane potential.
electrochemical gradients electrical and concentration gradients together.
passive transport simple diffusion, facilitated diffusion, and osmosis
active transport primary active transport, secondary active transport, and vesicular transport.
simple diffusion random mixing of particles in a solution as a result of the kinetic energy of those
particles. both the solvent and solute can diffuse. movement from high to low
concentrations.
what increases the rate of diffusion? steeper gradient, higher temperature, smaller particle, greater surface area, and
smaller diffusion distance.
diffusion through the lipid bilayer nonpolar, hydrophobic molecules. important for gas exchange, nutrient absorption,
and waste excretion.
leakage channel gates alternate from open to closed (Na and K)
voltage-gated channels open in response to a change in membrane potential (Na and K)
ligand-gated channels open and close in response to a chemical stimuli like hormones, neurotransmitters,
or other ions.
facilitated diffusion solute binds to a specific transporter protein and the transporter undergoes
conformational change. the solute then moves across the membrane and is
released on the other side only down its concentration gradient.
glucose, urea, fructose, galactose, and vitamins.
osmosis the net movement of a solvent through a selectively permeable membrane from an
area of high concentration to an area of low concentration.
, EXSS 256 Exam 1 | Comprehensive Exam Prep | Practice Questions, Answers & Detailed Rationales
hydrostatic pressure pressure that the water column exerts
osmotic pressure pressure a solution exerts when its particles are not permeable to the membrane;
proportional to the concentration of solute particles that cannot cross the
membrane.
tonicity how the osmolarity of a solution affects the cell volume
hypertonic tonicity of the solution is higher than the tonicity of the cell
hypotonic tonicity of the solution is lower than the tonicity of the cell
isotonic tonicity of the solution is the same as the tonicity of the cell.
primary active transport energy derived from ATP changes the shape of a transporter protein which pumps a
substance across a plasma membrane against its concentration gradient. most
prevalent is Na/K pump. requires 40% cellular ATP, operates continually, low Na and
high K in cytosol.
secondary active transport energy stored in Na or H ion concentration gradient used to drive other substances
against their own concentration gradients. creates ion gradients. symporters move
substrates in the same direction and antiporters move substrates in opposite
directions.
vesicle small membranous sac formed by budding off from an existing membrane.
endocytosis bringing something into the cell. phagocytosis is a cell eating and pinocytosis is a
cell drinking.
exocytosis release something from the cell.
metabolism the sum of all chemical reactions in the body.
catabolism breakdown; exergonic
anabolism building; endergonic
oxidation removal of electrons from an atom or molecule
