Temperature
Changes in temperature affect both phospholipids and membrane proteins, altering how effectively the membrane controls movement of substances.
| Condition | Effect on the membrane | Effect on permeability |
|---|---|---|
| Increasing temperature | Phospholipids gain energy, move more and become less tightly packed. | Substances can pass through the membrane more readily. |
| High temperature | The phospholipid bilayer becomes increasingly disrupted and membrane proteins can lose their normal conformation. | Membrane permeability rises further as control of movement is reduced. |
| Additional high-temperature effect | Expansion of water within cells can increase pressure on membranes and contribute to deformation of channel and carrier proteins. | The membrane becomes less effective at regulating what enters and leaves. |
| Below 0°C, after thawing | Transport proteins may be deformed and ice crystals can physically damage membranes. | Membrane permeability can be high even at the low-temperature end of the trend. |
Solvent concentration
Organic solvents such as alcohol or acetone can interfere with the lipid components of a membrane. As solvent concentration increases, this disruption can become greater, allowing more cellular contents to leak out.
Higher temperature
Increased phospholipid movement and damage to membrane components generally increase permeability.
Higher solvent concentration
Increasing disruption of the membrane lipids can lead to greater leakage from the cells.