Lecture 3-3: Principles and Molecules of Transmembrane Transport

Transmembrane Transport

Movement of substances across biological membranes.

Lipid Bilayer

A double layer of phospholipids that make up cell membranes, providing a barrier to the movement of certain molecules.

Concentration Gradient

A difference in concentration of a substance across a space, driving the movement of solutes.

Passive Transport

Movement of solutes across a membrane without the use of energy, following their concentration gradient.

Active Transport

The process of moving molecules against their concentration gradient, requiring energy input (usually from ATP).

Aquaporins

Specialized water channels that facilitate rapid transport of water across cell membranes.

Sodium-Potassium Pump

An ATP-powered pump that moves sodium out of and potassium into cells, maintaining electrochemical gradients.

Symporter

A type of transporter that moves two different solutes in the same direction across a membrane.

Antiporter

A transporter that moves two different solutes in opposite directions across a membrane.

Facilitated Diffusion

The process of spontaneous passive transport of molecules across a membrane via specific transmembrane integral proteins.

Gradient-Driven Pumps

Pumps that use the energy from the movement of one solute down its gradient to move another solute against its gradient.

Osmosis

The movement of water across a membrane from an area of low solute concentration to an area of high solute concentration.