diffusion Flashcards
what is diffusion
diffusion is the net movement of particles from a region of high concentration to a lower concentration down the concertation gradient
net movement
overall movement
what does passive process mean
does not require ATP
why is the cell membrane classed as partially permeable
because some chemicals can diffuse easily and some cannot
factors: concentration gradient
greater the concentration gradient greater the diffusion
factor: particle and size
charged particles such as ions cannot pass
smaller molecules will diffuse faster then larger ones
factor: temperature
warmer= more kinetic energy and can diffuse faster
factor : sA
larger surface area to volume ratio means faster diffusion
factor: distance
greater the distance slower rate of diffusion
facilitated diffusion
because hydrophilic substances cant pass through
passes through via protein molecules
what is involved in facilitated diffusion
intrinsic proteins- carrier proteins and channel proteins
carrier proteins in facilitated diffusion
carrier proteins have a binding site for a specific chemical this causes the tertiary structure of the carrier protein to change. which brings the chemical across the membrane
protein channels in facilitated diffusion
a protein with a central piore lined with hydrophilic amino acids and contains water so hydrophilic substances can pass across the membrane
They maybe selective to certain substances and need a trigger to allow substances through
are protein channels selective>?
yes, only certain ones can pass through through a chemical trigger
does facilitated diffusion require atp
no
