transport across membranes Flashcards
factors that affect the rate of transport across a membrane ?
- temperature (kinetic energy)
- surface area (larger area = more transport)
- volume or distance (bigger volume = bigger distance so it takes longer for particles to move across the membrane )
- concentration gradient
Fick’s law equation
rate of transport is directly proportional to size of surface area x distance in conc / transport distance or volume
what is the rate of diffusion if there is a shallow conc gradient, a large distance and the temp is 10 degrees ?
a slow rate of diffusion
what is the rate of diffusion if there is a steap conc gradient, small distance and the temp is 20 degrees ?
fast rate of diffusion
where does simple diffusion occur ?
through the phospholipid bilayer
what
is the definition of simple diffusion ?
the net movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached
this process does not require atp
hat kind of substances does simple diffusion only involve ?
small, lipid soluble substances
what happens to water soluble substances such as Na + in simple diffusion ?
the phospholipid bilayer acts as a barrier and bounces off Na+
what is used to transport water soluble molecules in facilitated diffusion ?
intrinsic proteins are used o transport molecules and allow their passage
what are the 2 types of facilitated diffusion ?
facilitated diffusion involving channel proteins
facilitated diffusion involving carrier proteins
hat do protein channels form ?
they form tubes filled with water which enable water soluble ions to pass through the membrane
at are channel proteins regarding the selectivity ?
channel proteins are specific
what do carrier proteins involve ?
a shape change
what do carrier proteins do ?
carrier proteins bind with a molecule which causes a change in the shape of a protein the shape change enables the molecule to be released to the other side of the membrane
