Diffusion Flashcards
what is the definition of diffusion?
the net movement of particles from an area of high concentration to low
what do carrier proteins do?
- move large molecules across membranes down their concentration gradient
- different molecules have different carrier proteins
what do channel proteins do?
- channel proteins form pores in the membrane for charged particles to diffuse through
- different channel proteins facilitate the diffusion of different charged proteins
which factors affect diffusion?
- concentration gradient
- thickness of the exchange surface
- surface area
how does the concentration gradient affect diffusion?
- the higher the concentration gradient the faster the rate of diffusion
- as diffusion occurs the difference in concentration decreases until equilibrium is reached
how does thickness affect diffusion?
the thinner the exchange surface the faster the rate of diffusion as the particles don’t have to travel so far
how does surface are affect diffusion?
the larger the surface area the faster the rate of diffusion
how can you increase the rate of diffusion?
add microvilli to increases the surface area so more particles can be exchanged in same amount of time
which factors affect facilitated diffusion?
- concentration gradient
- amount of channel or carrier proteins
how does the concentration gradient affect facilitated diffusion?
-the higher the concentration gradient the faster the rate of diffusion until equilibrium is reached
how do the number of channel proteins or carrier proteins affect facilitated diffusion?
-once all the proteins in the membrane are in use facilitated diffusion cant happen any faster even if the concentration gradient is increases
how do you increase the rate of facilitated diffusion?
-the higher the concentration gradient the faster the rate of diffusion until equilibrium is reached at which point the rate of diffusion levels off
how do carrier proteins work?
- a large molecule attaches to a carrier protein in the membrane
- then the protein changes shape
- the molecule is released on the opposite side of the membrane
what do microvilli do?
- projection formed by the cell surface membrane folding up on itself
- increase surface area 600x in human cells
what slows down diffusion?
- large particles diffuse slowly through the bilayer because of their size
- charged particles are water soluble so diffuse slowly as they cant pass through the hydrophobic bilayer
What is the concentration gradient?
The path from an area of high concentration to low which particles diffuse down
how is diffusion sped up?
-large or charged particles can diffuse through carrier proteins or channel proteins in the membrane which is called facilitated diffusion
what is facilitated diffusion?
- a passive process
- particles move down a concentration gradient
- involves charged
what is diffusion?
- molecules can diffuse both ways but the net movement will always be down the concentration gradient until equilibrium is reached
- passive process as it doesn’t require energy
- particles can diffuse across the cell membrane as long as they can freely move through the membrane which is called simple diffusion
what is the concentration gradient?
the path from an area of high concentration to low concentration which particles diffuse down
what is an example of simple diffusion?
- oxygen and cardoon dioxide can diffuse easily through cell membranes because they’re small and can pass through the gaps between the phospholipids
- they are non polar so are soluble in lipids and can pass through the hydrophobic bilayer
