BIOL 2160 chapter 4

cell membrane transport

this is the fluid mosaic model, a bilayer of phospholipids with proteinds interted into and attached to it

cell membrane structure

in the membrane these make very little water cross the membrane

phospholipids

____ or _____ molecules can freely cross the cell membrane, _______ or _____ molecules need carrier proteins to move acorss the membrane

small or nonpolar, large or polar

______ is transport across the membrane that requires energy, things moving from low to high concentration

active transport

____ transport is trasnport across the membrane that does not require energy, things moving from high to low concentration

passive 

______ _________ is the difference in charge between the inside and the outisde of the cell

membrane potential

the main ions that determine membrane potential for a cell are ____ and ___

Na+ and K+

there is more K+ ___ than ___ the cell. there is more Na+ ____ than ____ the cell always

inside than outside, outside than inside

ion concentrations do not even out because they have a _____ they can only cross the membrane with the help of membrane proteins 

charge

_____ is the difference in energy across a membrane, its force pushes from higher to lower energy

driving force

________ driving force is the concentration gradient, _____ affects charged ions, _____ is determined by the combination of the other two

chemical, electrical, electrochemical

the chemical force always wants to move ____ out of the cell, it always wants to move ____ into the cell

K+, Na+

the chemical force of these ions never changes because the ______ of these ions across the membrane never changes

concentration

electrical driving force depends on the ________

membrane potential

for electrical driving force Na+ and K+ will both be _____ to negatively charged areas and __________ postively charged areas

attracted, repelled by

membrane potential at rest for most cells is _____

-70 mv

_________ ________ is the membrane potential for each ion where the electrical force is larger than the chemical force, and the ion is now controlled by the electrical force

eqillibrium potential

usually the ion of Na+ and K+ are controlled by the _____ force because…

chemical force because the gradient is so large

most of the time Na+ will go into the cell when equillibrium potential is at +55mv, it will leave when…

mv goes above +55mv (more postive)

K+ will usually leave the cell at -94mv equillibrium potential but it will go in the cell when…

mv goes below -94 (more negative)

the membrane portential at any time will always be approaching the equilibrium potential of the …

most permeable ion

_____ ____ is small nonpolar molecules moving directly though the membrane from high to low conc

simple diffusion

simple diffusion is the result of …

thermal motion

________ _____ involves a ptoein in the membrane that changes shape and moves something across the membrane from high to low (passive trasnport)

facilitated diffusion

what invloves transporting an ion across the membrane through a protein with a hole (pore) in it that the ion passses through

diffusion through ion channels

what type of diffusion do Na+ and K+ use to move through the membrane

they diffuse through ion channels through the membrane

the rate of simple diffusion is determined by: _____, ______ and _____

driving force, membrane surface area, and membrane permeability

as membrane surface increases the rate of simple diffusion _____

increases

membrane permeability is affected by: _____, _____, _____ and ______

lipid solubility, size and shape of the molecule, temperature, membrane thickness

primary active transport uses ____ directly to provide neergy for molecules to move against their gradient

ATP

secondary active trasnport uses the energy from… 

one molecule moving passively down its gradient to provide energy for another molecule to move up its gradient 

two types of secondary active trasnport: ____ moves in the same direction, and ____ is when molcules move in opposite directions

cotransport, countertransport

what is the most important primary active trasport mechanism in the body

Na+ and K= ATPase (pump)

the purpose of the ATPase pump is to move Na+ ____ and K+ ____, this is why chemicla driving force _____, as soon as the ions move across they are trasnported back to where they came from

out, in, stays the same

what is the movement of water across a membrane from an area of low concentration SOLUTE to high concentration solute, diluting it until there is an equal concetration of solute on both sides of the membrane

osmosis

osmosis is always _____ transport, why?

passive, high concentration water → low concentration water

____ is the total solute particle concentration of a solution

osmolarity

is the intracellular and extracellular solution have the same solute concentration they are _____

isotonic

if the intracellular solution is 8M it is ____ to 3M outside the cell

hypertonic

if the intracellular solution is 3M it is ______ to 8M extracellular solution

hypotonic

when water moves into the cell, it will ______, when water moves out of the cell it will ______

swell, shrink

_____ is large molecules entering the cell where the membrane surrounds a particle, encloses it in a vesicle and brings it into the cell

endocytosis

____ is cell eating any non specific solid particle

phagocytosis

_____ is cell drinking any nonspecific fluid

pinocytosis

____________ endocytosis involves a specific molecule, usually a neurotrasnmitter or hormone that binds a specific receptor and gets taken into the cell

receptor mediated

______ is the reverse of endocytosis, large molecules are packaged in vesicles whcih fuse with the membrane and release these molecules to the outisde of the cell

exocytosis