Please enable JavaScript.
Coggle requires JavaScript to display documents.
Diffusion (Facilitated Diffusion (It is from an area of high…
Diffusion
Facilitated Diffusion
-
Large and charged particles pass through transport proteins so that they can diffuse across the membrane to get in and out of the cell.
Facilitated diffusion requires transport proteins, unlike simple diffusion. However, it doesn't require ATP like active transport does.
Factors Affecting:
- The higher the concentration gradient the higher the rate of diffusion.
- The higher the number of transport proteins means the higher the rate of diffusion because there are more proteins for substances to diffuse through.
Simple Diffusion
No transport proteins are needed like in facilitated diffusion and active transport. No ATP is needed like in active transport.
The net movement of a substance from an area of high concentration to an area of low concentration, through a partially permeable membrane.
Molecules like oxygen and carbon dioxide and water which can all go through the phospholipid bilayer.
Diffusion General
The thinner the exchange surface the higher the rate of diffusion as the substance will have a much shorter distance to travel.
The larger the surface area of a cell the higher the rate of diffusion for that cell because there are more areas in which substances can diffuse through the cell-surface membrane.
The higher the concentration gradient the higher the rate of diffusion through a cell-surface membrane.
Transport proteins
Carrier
- Then, the protein changes shape.
- This releases the molecule on the opposite side of the membrane.
- Firstly, a molecules binds to a carrier protein in the cell-surface membrane.
Channel
- Molecules can diffuse through them if they are to big or are charged.
- Channel proteins are pores in the cell-surface membrane.