Membrane Transport

Front 1

membrane permeability
permeable to...

Back 1

permeable to: small, nonpolar, uncharged molecules, water

Front 2

plasma membrane
impermeable to...

Back 2

ions and charged or polar molecules

Front 3

concentration gradient

Back 3

the difference in the concentration, [x] of a chemical b/w one side of the plasma membrane &the other

O2 and Na ions, greater [] outside the cell

CO2 and K ions, greater [] inside cell

Front 4

electrical gradient

Back 4

inner surface of the membrane= more negatively charged

outer surface= more positively charged

AKA membrane potential

Front 5

electrochemical gradient

Back 5

concentration & electrical gradients together

Front 6

diffusion

Back 6

random mixing of particles in a solution as a result of the kinetic energy of those particles

both the solvent & solute can diffuse

movement from area of [high] to [low]

Front 7

rate of diffusion depends on (5 things)

Back 7

1) temperature (+,+)
2) size of particles (<,+)
3) steepness of gradient (+,+)
4) surface area (>,-)
5) diffusion distance/ thickness of membrane (the thicker the slower)

Front 8

osmosis

Back 8

net movement of a SOLVENT through a selectively permeable membrane

i.e. mvmnt of water (the solvent) from an area of [higher] to [lower] across the membrane

water moves via diffusion through lipid bilayer or aquaporins

Front 9

hydrostatic pressure

Back 9

pressure that the water column exerts (prevents water from diffusing through the membrane)

Front 10

osmotic pressure

Back 10

pressure a solution exerts when its particles are not permeable to the membrane; proportional to [solute] particles that cannot cross the membrane

Front 11

molarity

Back 11

concentration of a particular solute in a solution

Front 12

osmolarity

Back 12

ratio of solute to solvent

Front 13

hypertonic

Back 13

tonicity of the solution is higher than tonicity of the cell

higher [impermeable solute] outside of cell than inside

Front 14

hypotonic

Back 14

tonicity of the solution is lower than the tonicity of the cell

higher [impermeable solute] inside the cell than outside

Front 15

hemolysis

Back 15

when the cell swells due to being in a hypotonic solution, RBC undergoes this

Front 16

crenation

Back 16

when a RBC shrinks, looses too much water, due to being in a hypertonic solution

Front 17

types of passive transport

Back 17

1-diffusion
2-diffusion through ion channels
3-facilitated diffusion

Front 18

1) diffusion through the lipid bilayer

Back 18

nonpolar, hydrophobic molecules (respiratory gases, some lipids)

important for gas exchange, nutrient absorption, waste excretion

Front 19

types of ion channels

Back 19

1-leakage channels
2-voltage-gated channels
3-ligand-gated channels

Front 20

leakage channels

Back 20

gates alternate from open to closed

type of ion channel

Front 21

voltage-gated channels

Back 21

type of ion channel

open in response to a change in membrane potential (aka electrical gradient)

Front 22

ligand-gated channels

Back 22

type of ion channel

open & close in response to a chemical stimuli like hormones, neurotransmitters or other ions

Front 23

diffusion through ion channels

Back 23

most membrane channels are ion channels

allow passage of small, inorganic, hydrophilic ions

these channels are selective & specific

Front 24

facilitated diffusion

Back 24

1) solute binds to a specific transporter protein

2) transporter undergoes conformational change

3) solute moves across membrane and is released on other side (down its conc. gradient)

Front 25

solutes that move via facilitated diffusion

Back 25

glucose, urea, fructose, galactose, some vitamins

Front 26

primary active transport

Back 26

-most prevalent - Na/K pump
-requires 40% of cellular ATP
---energy from ATP changes shape of a transporter protein
-maintains low [Na+] and high [K+] in the cytosol
-operates continually
-maintains & regulates cell volume

Front 27

Na/K pump how much in how much out?

Back 27

3 Na+ ions are exported out
2 K+ ions are imported into cell

((all against gradient))

Front 28

secondary active transport

Back 28

*creates ion gradients

Energy stored in Na+ or H+ ion concentration gradient used to drive other substances AGAINST their own concentration gradients (usually Na influx) there are 2 types: symporters and antiporters

Front 29

symporters

Back 29

aka cotransporters

moves substrates in the SAME direction (Na/glucose, Na/K/Cl, Na/Cl)

Front 30

antiporters

Back 30

aka exchangers

moves substrates in OPPOSITE directions (Na/Ca exchanger, Na/H exchanger)

Front 31

vesicle

Back 31

small membranous sac formed by budding off from an existing membrane

Front 32

endocytosis

Back 32

bringing something into the cell

Front 33

exocytosis

Back 33

release something from cell

-vesicles form inside cell, fuse to cell membrane
-release their contents (digestive enzymes, hormones, neurotransmitters or waste products)

Front 34

phagocytosis

Back 34

cell eating by macrophages and WBCs
-type of endocytosis

Front 35

pinocytosis

Back 35

cell drinking
-type of endocytosis