fators affecting permeability

What are the 2 factors that affect permeability

Temperature and solvents

What is a solvent

A iquid that had the ability to dissolve substances

What are examples of organic or non-polar solvents

Ethanol and Methanol

What happens when cells are placed in a solvent

The phospholipids dissolve, so the membrane becomes more fluid/permeable

What does increasing the conc of true solvent do to the permeability

It increases the permeabilty

How do you get drunk

The permeability of the cell membrane of a neuron increases, more sodium and potassium ions pass through the channel proteins and this slows the nervous system down

What happens to cells at high temperatures (40+)

They have lots of kinetic energy, so there is more movement so increase permeability. Too much movement makes the bilayer break down and channel proteins break down, allowing other molecules to diffuse in/out

What happens to cells at normal temperatures (0-40)

As temp increases, so does kinetic energy, so the bilayer is more fluid/permeable

What happens to cells at low temperatures (below 0)

They have no kinetic energy, so the permeability is 0

If a frozen cell is thawed, what happens

Water expands when frozen, pressurising the membrane

When frozen, water forms ice crystals that pierce the membrane

When it unfreezes, it leaves holes which increases permeability