Diffusion Flashcards
How do molecules diffuse in a net movement
Both ways but the net movement will be to the area of lower concentration and this continues till the particles are evenly distributed
What is the concentration gradient and how do particles move
The path of of an area of higher concentration to an area of lower concentration
The particles diffuse down the concentration gradient
Is energy required for diffusion
Diffusion is a passive process so no energy is required
How can particles diffuse across the cell membrane
They have to move freely through the membrane
What is simple diffusion
When molecules diffuse directly through the cell membrane
What type of molecules can do simple diffusion and hive two examples
Small molecules
Polar molecules
Oxygen and carbon dioxide
Why does it take longer for charged particles to diffuse slowly
They’re water soluble and the centre of the bi layer is hydrophobic
What is facilitated diffusion
Charged or large particles diffuse through carrier and channel proteins a in the membrane
How does facilitated diffusion move down the concentration gradient
From a high to low concentration
What does carrier proteins move
Larger molecules
Can one carrier proteins facilitate all different ions or molecules
No different carrier proteins facilitate the diffusion of different molecules
How do carrier proteins work
First large molecules attach to a carrier protien in the membrane
Then a the protien changes shape
This releases molecules on the opposite side of the membrane
What do channel proteins form
Pores in the membrane for the charged particles to diffuse
Can one channel protien facilitate the diffusion of different molecules
Different channel proteins facilitate the diffusion of differently charged particles
What moves mostly in channel proteins
Aquaporins - water molecules move through
Ions
What does simple diffusion rate of diffusion depend on
Concentration gradient - higher it is the faster the rate of diffusion
The thickness of exchange surfaces - the thinner the exchange surface the faster the rate of diffusion
The surface area -the larger the surface area the faster the rate of diffusion
How does microvilli increase surface area for faster diffusion
Larger surface area means that more particles can be exchanged in the same amount of time
What factors does facilitated diffusion depend
The concentration gradient - higher the concentration gradient faster the rate of facilitated diffusion
The number of channel or carrier proteins -greater the number of these proteins the faster the rate of diffusion
Why does diffusion rate not increase even if the concentration increases
Because if all the proteins are in use facilitated diffusion then the rate doesn’t increase
What are aquaporins
Special channel proteins that allow facilitated diffusion of water through cell membranes
What does having more aqauporins do for the kidneys
Allow cells to reabsorb a lot of water that would otherwise be excreted by the body
What does having more channel proteins do in facilitated diffusion
Increases the rate of diffusion
