What are the energy sources for active transport?

The primary energy sources for active transport are adenosine triphosphate (ATP) and electrochemical gradients.

Active transport is a process that moves ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy. This energy is primarily provided by adenosine triphosphate (ATP), a complex organic chemical that provides energy to drive many processes in living cells. ATP is often called the "energy currency" of the cell because it can store and release energy as needed by the cell.

In active transport, ATP provides the energy to move ions or molecules against their concentration gradient, from an area of lower concentration to an area of higher concentration. This is achieved by the hydrolysis of ATP, which releases energy. The energy is used to change the shape of a transport protein, allowing the molecule or ion to be moved across the membrane.

Another source of energy for active transport is electrochemical gradients. These are gradients of both chemical concentration and electric potential. In cells, these gradients are created by the action of primary active transporters, which use ATP to pump ions out of the cell. The resulting gradient can then be used as an energy source for secondary active transport. This is known as secondary active transport or co-transport.

For example, the sodium-potassium pump, a type of primary active transporter, uses ATP to pump sodium ions out of the cell and potassium ions into the cell. This creates a gradient of sodium ions, which can then be used as an energy source to drive the transport of other molecules, such as glucose, into the cell. This is an example of secondary active transport.

In summary, ATP and electrochemical gradients are the main energy sources for active transport, driving the movement of ions and molecules against their concentration gradients.