Faactors affecting membrane structure and permeability

Temperature: below zero degrees Celsius

• permeability increases

• proteins in membrane unfold and become deformed

• molecules have little energy - membrane becomes rigid

• ice crystals form and puncture membrane so when it melts increases permeability due to damage of cells

Temperature: between 0-45 degrees

• partially permeable

• at temp increases, components of membrane gain kinetic energy

• move around more so membrane becomes more fluid

• more fluid = more permeable

Temperature: above 45 degrees

• permeability increases rapidly

• carrier and channel proteins become denatured

• water inside cell expands and puts pressure on the cell membrane and create gaps within bilayer

Ethanol

• ethanol is a non-polar solvent

• dissolves lipids

• membrane will become permeable

• as ethanol concentration increases so does permeability

• can completely disintegrate membrane + kill cell