2. Diffusion - simple Flashcards
Define diffusion.
The net movement of particles from an area or higher concentration to an area of lower concentration.
Molecules diffuse both ways, but the net movement will be to the area of lower concentration - continue until equilibrium.
What is a concentration gradient?
Is the path from an area of higher concentration to an area of lower concentration.
Particles diffuse down a concentration gradient.
What kind of process is diffusion?
Passive.
No energy needed for it to occur.
Particles diffuse across cell membrane as long as they can move freely through membrane.
What is simple diffusion?
When molecules diffuse directly through cell membrane.
EXAMPLE.
How can oxygen and carbon dioxide diffuse easily through cell membrane?
They’re small - pass through spaces between phospholipids.
Non-polar - soluble in lipids, they can dissolve in hydrophobic bilayer.
What 3 things affect the rate of diffusion?
Concentration gradient.
Thickness of exchange surface.
Surface area.
How does the concentration gradient affect rate of diffusion?
Higher it is, faster the rate of diffusion.
As diffusion takes place, the difference in concentration between the 2 sides of the membrane decreases until equilibrium - diffusion slows down over time.
How does the thickness of the exchange surface affect rate of reaction?
Thinner exchange surface the faster the rate of diffusion.
How does the surface area affect rate of reaction?
Larger surface ares the faster rate of diffusion.
EXAMPLE.
Give an example of a specialised cells can increase surface area?
Microvilli.
In human cells microvilli can increase surface are by about 600 times.
