05. Simple diffusion

What is simple diffusion?

Diffusion of non polar molecules (e.g. oxygen and carbon dioxide) across the phospholipid bilayer

What molecules can diffuse by simple diffusion?

Lipid soluble, uncharged, non polar molecules e.g. oxygen

Describe the movement in simple diffusion?

Movement of molecules / ions from high concentration to low concentration until equally distributed

How does diffusion move in relation to the concentration gradient?

Moves down concentration gradient

What kind of process is simple diffusion?

A passive process -> no atp needed

What is the result at the end of simple diffusion?

Equilibrium will be reached unless molecule used by cell

What happens at EQM?

No net movement in a particular direction -> molecules + particles continue to cross membrane in both directions

What does equilibrium mean?

Concentration of molecules equal on either side of membrane

Draw the graph of diffusion

Yes

Describe the simple diffusion graph? Why is it like this?

It’s linear -> conc. of gradient increases = rate of diffusion increases

How does rate of uptake and concentration difference across membrane relate?

They are directly proportional

How does stopping respiration or killing the cell with toxin affect diffusion?

Will not stop diffusion as it does not need ATP

What factors have no affect on diffusion?

Rate of respiration or toxins e.g. respiratory inhibitors like cyanide