What are examples of active transport in human cells?

Active transport in human cells includes the sodium-potassium pump, glucose transport, and the transport of amino acids.

The sodium-potassium pump is a crucial example of active transport in human cells. This pump is a protein that spans the cell membrane and uses ATP (adenosine triphosphate) to move three sodium ions out of the cell and two potassium ions into the cell. This process is against the concentration gradient, meaning it moves ions from an area of lower concentration to an area of higher concentration. This pump is essential for maintaining the cell's resting potential, enabling nerve impulse transmission, and providing the energy for co-transport of other molecules.

Glucose transport is another example of active transport. Glucose is a vital source of energy for cells. However, because the concentration of glucose is often higher inside the cell than outside, it cannot simply diffuse across the cell membrane. Instead, cells use a process called secondary active transport. In this process, glucose is transported along with sodium ions via a protein carrier. The energy for this process comes indirectly from ATP, used by the sodium-potassium pump to maintain the sodium gradient.

The transport of amino acids into cells is also an example of active transport. Amino acids are the building blocks of proteins and are essential for cell growth and repair. Like glucose, amino acids often need to be transported against a concentration gradient. This is achieved through a process similar to glucose transport, where amino acids are co-transported with sodium ions into the cell.

In summary, active transport is a vital process that allows cells to maintain their internal environment and obtain necessary nutrients. It involves the use of energy, usually in the form of ATP, to move substances against their concentration gradient. Examples in human cells include the sodium-potassium pump, glucose transport, and the transport of amino acids.