Biology – 3.3 Active transport | e-Consult

The purpose of active transport is to maintain the correct internal environment (homeostasis) within the cell. This includes maintaining specific ion concentrations, removing waste products, and accumulating essential nutrients. It ensures that the cell can function optimally by controlling the movement of substances across its membrane.

Active transport is dependent on the availability of ATP because the energy required to move molecules against their concentration gradient is directly supplied by ATP hydrolysis. ATP provides the energy for the conformational changes in the carrier proteins, enabling them to bind to and transport the molecule. Without ATP, the carrier proteins cannot change shape and the transport process will cease.

A common example of a substance transported by active transport is sodium ions (Na⁺) in animal cells. The sodium-potassium pump is a prime example of active transport. This pump maintains the electrochemical gradient across the cell membrane, which is essential for nerve impulse transmission and muscle contraction. The sodium-potassium pump actively pumps sodium ions out of the cell and potassium ions into the cell, requiring ATP. This gradient is crucial for the proper functioning of the nervous and muscular systems.