3.6 Active Transport

Active transport

Mechanisms that require the use of the cell’s energy, usually in the form of ATP, to move substances against their concentration gradient.

Electrochemical gradient

The combined effects of concentration gradients and electrical gradients that affect ion movement across membranes.

Primary active transport

Transport mechanisms that use ATP to move ions across a membrane, creating a charge difference across that membrane.

Sodium-potassium pump

An important primary active transport system that expends energy to move potassium ions into the cell and sodium ions out of the cell.

Secondary active transport

Movement of materials using the energy of the electrochemical gradient established by primary active transport.

Endocytosis

A type of active transport that moves large particles or fluids into a cell by forming a pocket in the plasma membrane.

Phagocytosis

The process by which large particles, such as cells, are taken in by a cell, often involving engulfment.

Pinocytosis

A form of endocytosis that involves the engulfing of extracellular fluid and solutes; often referred to as 'cell drinking'.

Receptor-mediated endocytosis

A targeted form of endocytosis that involves specific binding proteins on the plasma membrane for the uptake of substances.

Exocytosis

The process of expelling material from the cell into the extracellular fluid by fusion of a vesicle with the plasma membrane.