diffusion Flashcards
defenition of diffusion
passive movement of a molecule down a concentration gradient (high to low)
passive defenition
not requiring energy provided by the cell
what happens when molecules reach equilibrium
no net movement
what are the main things that affects rate of diffusion
concentration gradient
length of diffusion path
surface area of membrane
what is the diffusion equation
rate of diffusion =
length of diffusion path
2 less important things which effect rate of diffusion
size of molecule - small is faster
temperature - inc temp, inc kinetic energy
what is rate of uptake in direct and proportionate level with
oxygen concentration
defenition of facilitated diffusion
passive transfer of molecules down a concentration gradient across a membrane by chanel or carrier protein molecules in the membrane
what does facilitated diffusion use
chanel or carrier protein molcules in the membrane
why cant glucose pass through cell membrane
they are insoluble in phospholipid bilayer
what type of process is facilitated diffusion
passive
so happens down a concentration gradient
what limits the rate of facilitated diffusion
number and availability of transport protein molecules
2 types of transport proteins
channel proteins
carrier proteins
what makes channel proteins special
molecules with pores lined with polar groups
are channel proteins hydrophobic / hydrophilic
hydrophilic - can pass through
what do channel proteins do
open and close according to the needs of the cell
simply what does carrier proteins allow
diffusion of larger polar molecules such as amino acids
how do carrier proteins work
mol attatches to its binding site on the carrier protein
carrier proteins changes shape and releases mol on other side of membrane before changing to original shape
difference in channel proteins and carrier proteins
carrier doesn’t have pores
carrier can transport against conc radient
carrier can change shape
carrier is a slower transport
explain graph line of facilitated diffusion uptake and amino acid concentration
directly proportional up to a speicifc pooint and then levels off because all of the carriers are occupied
