B3.1 Membrane Transport

Molecules moving across a cell membrane from a region of higher concentration to a region of lower concentration without the use of energy

The movement of particles from a region of high concentration to a low one, creates an equilibrium

The concentration gradient, the surface area, the length of diffusion path

They bind to receptors and move towards the cytoplasm or nucleus of a cell

It is the diffusion of water because the cell membrane is impermeable to solutes.

Isotonic = equilibrium Hypotonic = water moves into the cell Hypertonic = water moves out of the cell

Water often moves into the cell, turgor pressure is exerted against the cell wall

Large and polar molecules cant get across the membrane, so they use a transmembrane protein as a vessel Channel proteins and carrier proteins

It requires ATP, integral protein pumps use ATP to move ions or large molecules uses across the cell membrane

A adenosine and triphosphate and attached, when one phosphate is removes it releases energy

Uniporter = one molecule can pass through Symporter = Two molecules pass through in the same direction Antiporter = Two molecules pass through in the different directions