Active Transport in Cells

Tuesday, August 1, 2017

Active Transport in Cells

In this video, I review three types of active transport, pumps, exocytosis, and endocytosis.
Cells use active transport in order to move objects into the cell.

*Membrane pumps 

A membrane pump moves substances against the concentration gradient or from a low concentration to a high concentration.
A good example is a sodium-potassium pump.

Three sodium ions attach to the carrier protein. 
ATP attaches a phosphate to the carrier protein and it changes its shape. This allows three sodium ions to leave the cell and two potassium ions to now attach to the protein.
The phosphate detaches from the protein and the potassium now travels into the cell.
The ratio is 3 sodium ions for every 2 potassium ions.

sodium potassium pump

The cell also uses two types of vesicle movement endocytosis and exocytosis which allows  Endocytosis allows the cell to move larger
objects into the cell by engulfing the object and moving the object into the cell.


There are three types of endocytosis.
*Phagocytosis is when a cell moves in solids.
*Pinocytosis is when a cell moves in liquids.
*Receptor-mediated endocytosis is a form of endocytosis in which receptor proteins on the cell surface are used to capture a specific target molecule. 

When the receptors bind to their molecule, endocytosis is triggered, and the receptors and their attached molecules are taken into the cell in a vesicle.

*Exocytosis occurs when  the cell expels an object out of the cell
Objects inside the cell are encased in a vesicle which is expelled.

Again each of these processes requires energy in the form of ATP.


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