Active transport in cells

In order to stay alive, cells need to move objects into and out of the cell. There are two types of cellular movement. Passive transport which does not require energy, and active transport which requires energy.

Think of passive transport as riding a bike down a hill and active transport riding the bike up the hill. Which requires more energy? Yes, the active transport.

Let’s see why active transport requires energy. Sometimes the cell needs to move objects from low concentration to high concentration or up the concentration gradient. Other times a cell may need to move large objects through the membrane. In these instances, active transportation is used and active transportation requires energy.

active transport

This energy is supplied by the energy molecule ATP adenosine triphosphate.

atp

There are at least three types of active transport, membrane pumps, endocytosis, and exocytosis.

A membrane pump such as a sodium potassium pump move substances up the concentration gradient or from  low concentration to a high concentration. The sodium potassium pump moves three sodium ions for every two potassium ions into the cell. The cell uses ATP as energy and the channel changes its shape and allows the sodium and potassium to move into and out of the cell.

active transport

The cell also uses two types of vesicle movement called endocytosis and exocytosis which allows large objects into and out of the cell. Endocytosis allows the cell to move larger objects into the cell by engulfing the object and moving the object into the cell. During exocytosis the cell expels an object out of the cell. For example, a neuron uses exocytosis to expel the neurotransmitters that are enclosed in a vesicle. There you go, active transport where energy is used to move objects into and out of a cell.