What is the purpose of active transport?

Active transport moves molecules across concentration gradients using energy in the form of ATP to maintain the correct concentrations of ions and molecules in cells. Cells use most of their energy for their metabolism to keep processes active. For example, the majority of a red blood cell’s energy is used to maintain internal potassium and sodium levels that are distinct from those of the external environment. Primary active transport directly uses a source of chemical energy (ATP) to transport molecules against their gradient. Secondary active transport uses the electrochemical gradient, created by active transport as its energy source to transport molecules against their gradient. Thus, it does not require a direct source of energy like ATP. Active transport is also crucial to accumulate the necessary amino acids for cell survival.