Factors affecting permeability

how does cold temperatures affect cell membrane structure?

• decrease in kinetic energy of the phospholipids, which decreases the movement of the membrane

• the membrane becomes less fluid and therefore more rigid, therefore decreasing its permeability

• Unsaturated fatty acids have kinks which keep the phosphides at a distance from each other

• cholesterol between the phospholipids keep the phospholipids apart to prevent them from becoming crystalline

What happens to the cell membrane when the temperature is 0C or below?

• Phospholipids have such a low K.E, so they have very restricted movement and are very close together

• this causes ice crystals to form on the outer layer of membranes and pierce the membrane which therefore increases permeability of the membrane

how does Hot temperatures affect cell membrane structure?

• There is an increase in kinetic energy of the phospholipids, which therefore increases the movement of the lipids

• phospholipids begin to drift, however interaction with cholesterol decreases drift and movement of phospholipids

• Proteins begin to drift, or deform causing pores in the membrane

• this causes membrane to become more fluid and therefore permeability increases

What happens to the cell membrane when it is really hot?

• The Phospholipid bilayer begins to melt and the membranes permeability increases

• Water inside of the cell then begins to expand which causes the pressure inside of the cell to increase and apply it on the membrane

• Channel proteins and carrier proteins begin to denature, which then creates gaps in the membrane which increases the permeability of the cell membrane

What factors other than temperature affect the permeability of membranes?

• Organic solvents which are added

How do solvents affect the permeability of membranes?

• They break the esther bonds between the heads and the fatty acids

• This dissolves the lipids in the membranes which therefore increases the permeability