Membrane Permeability

AQA AS-level BiologyTransport Across Cell MembranesLesson 8 of 22

The plasma membrane is selectively permeable.

This means it selectively prevents or allows the passage of different molecules across the membrane.

Lipid soluble molecules such as steroid hormones can dissolve in the bilayer and pass through the membrane.

Sign in free to see the rest of this lesson, the R.E.C.I.P.E. recall steps and the quiz

BrainCake is free. Make an account in seconds and pick up where this page stops.

phospholipid: A lipid in which one fatty acid is replaced by a phosphate group, giving a hydrophilic head and hydrophobic tails.
diffusion: The net passive movement of molecules or ions from a region of higher concentration to a region of lower concentration, down a concentration gradient.
facilitated diffusion: The passive movement of molecules or ions down their concentration gradient through protein channels or carrier proteins.
active transport: The movement of molecules or ions across a membrane from a region of lower to higher concentration, against the concentration gradient, using ATP and carrier proteins.