30290652
Description
Mind Map by Flo Sumpter, updated more than 1 year ago
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Created by Flo Sumpter
about 3 years ago
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B1 cells - Diffusion
- DEFINTION - diffusion is the spreading out of
particles from an area of higher concentration to an
area of lower concentration
- diffusion is simple - it's just the gradual movement of particles from places
where there are lots of them to places where there are fewer of them - natural
tendency for stuff spreading out.
- Diffusion happens in both solutions and gases - that's
because the particles in these substances are free to
move about randomly
- the simplest type is when different gasses diffuse through each other.
- the bigger the concentration gradient (the
difference in concentration) the faster the
diffusion rate
- A higher temperature will also give a
faster diffusion rate because the
particles have more energy, so move
around faster.
- Cell membranes are kind of clever
- they are clever because they hold the cell together BUT they
let stuff in and out as well
- Dissolved substances can move in and out of cells
by diffusion
- only very small molecules can diffuse through cell
membranes though - things like oxygen, glucose,
amino acids and water
- Big molecules like starch and proteins can't fit through the
membrane
- just like with diffusion in air, particles flow through the cell
membrane from where there's a higher concentration to
where there's a lower concentration.
- they're only moving about randomly of course, so they go both ways -
but ig there are a lot more particles on one side of the membrane,
there's a net (overall) movement from that side
- the larger the surface area of the membrane, the faster the diffusion rate, because
more particles can pass through at once.
- they are clever because they hold the cell together BUT they
let stuff in and out as well
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