Diffusion

HideShow resource information
  • Created by: zoolouise
  • Created on: 19-04-16 19:36
What is the definition of diffusion?
Diffusion is the overall net movement of molecules or ions from a region where they're in high concentration to a region of lower concentration until they are equally distributed.
1 of 20
What is the definition of the concentration gradient?
The path from an area of higher concentration to an area of lower concentration, particles diffuse down a concentrationg radient.
2 of 20
What is diffusion an example of and where does the energy come from?
It's an example of passive transport and the energy comes from the natural, inbuilt motion of particles rather than from an external source.
3 of 20
What do you need to understand in diffusion?
Particles are constantly in motion due to kinetic energy, the motion is random with no set pattern. Particles are constantly bouncing off one another as well as off other objects.
4 of 20
How does concentration gradient affect the rate of diffusion?
The greater the difference in concentration of molecules in two areas, the greater the rate of diffusion
5 of 20
How does the surface area of the membrane affect the rate of diffusion?
The larger the area, the quicker the rate of diffusion
6 of 20
How does the thickness of the membrane affect the rate of diffusion?
The thinner the membrane, the quicker the rate of diffusion
7 of 20
How does the distance of travel affect the rate of diffusion?
The shorter the distance between two areas, the greater the rate
8 of 20
How is diffusion in cells also affected?
The nature of plasma membrane - its composition and number of pores. The size and nature of the diffusing molecule - small molecules diffuse faster than big ones. Fat-soluble molecules diffuse faster water-soluble, polar molecules faster non-polar
9 of 20
Why is there faciliated diffusion?
Larger molecules would diffuse slow as they're so big, charged would diffuse slowly as they're water soluble.
10 of 20
What does faciliated diffusion do?
It speeds things up by allowing large or charged particles to diffuse through carrier proteins or channel proteins in the cell membrane instead. Moves particles down a concentration gradient.
11 of 20
Where does faciliated diffusion occur?
At specific points on the plasma membrane, where there's protein molecules called transport molecules.
12 of 20
What do channel proteins do?
Form pores in membrane lined w/polar groups for charged molecules to diffuse. Water-soluble substances can pass through as they're hydrophillic.
13 of 20
What do carrier proteins do?
They form and allow the diffusion of larger molecules such as sugar and amino acids.
14 of 20
How does a carrier protein carry out its function?
A particular molecule attaches to it in the membrane at the binding site, carrier protein changes shape, releases the molecule on the opposite side of the membrane.
15 of 20
What is each transport protein?
It's selective, opening only in the presence of a specific molecule.
16 of 20
What are some factors affecting faciliated diffusion?
The concentration gradient - higher concentration gradient, faster rate of diffusion. Number of channel/carrier proteins - once they're all used, faciliated diffusion can't happen any more even with increase in concentration gradient
17 of 20
What happens as equilibrium is reached?
The faciliated diffusion will level off.
18 of 20
What is Flick's Law?
It states that diffusion is proprtional to: Rate of diffusion = (surface area x difference in concentration) / length of diffusion pathway
19 of 20
How does an increase in temperature affect the rate of diffusion?
It increases the rate as there's an increase in molecular energy and therefore movement
20 of 20

Other cards in this set

Card 2

Front

What is the definition of the concentration gradient?

Back

The path from an area of higher concentration to an area of lower concentration, particles diffuse down a concentrationg radient.

Card 3

Front

What is diffusion an example of and where does the energy come from?

Back

Preview of the front of card 3

Card 4

Front

What do you need to understand in diffusion?

Back

Preview of the front of card 4

Card 5

Front

How does concentration gradient affect the rate of diffusion?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cellular processes resources »