All types of cells have the process of active transport.
This is the action where molecules from one highly populated area move through the membrane to a location with a lot less molecules.
The goal is to try to keep a good balance. In order for the cell to detect the population it requires a recognition of the concentration gradient.
This is where fewer molecules meet at a place where there are large numbers of molecules.
Moving from low concentration to high concentration locations is called going “against the gradient.”
Molecules need energy to accomplish active transport and they get that energy from the cell.
When the molecules have movement that doesn’t require energy it is called “passive transport.”
The process of active transport moves molecules that the cell needs such as amino acids, glucose, or ions.
For active transport there is a primary and secondary type and the difference between the two is in the type of energy used.
Primary transport is referred to as “direct active transport” because it makes use of chemical energy for moving molecules.
A standard method of using energy in the cell is through chemical energy and takes the form of ATP.
An example of primary transport is the pumping of sodium out of the cell and pumping potassium into the cell. This is called the sodium-potassium pump.
Secondary transport is referred to as “co-transport” and the energy that it uses to move molecules out or into the cell is electrochemical energy.
This process involves moving one molecule from a high concentration area into a low concentration area.
The process of the movement itself creates energy that can be used. This gives the ability to move another molecule against the gradient, in the opposite direction.
Due to the various requirements, there are 3 different types of active transporters that are needed:
In active transport it’s the proteins that are the “heavy lifters,” and each protein is very specialized.
Since active transport typically happens in moving molecules across the cell membrane, there are thousands of proteins that exist in a cell’s lipid bilayer.
They are positioned to be able to cross the membrane so that one part of the protein is on the outside of the cell and one part is on the inside of the cell.
Then they can move ions and molecules in or out of the cell. Their specialization also means that they can only move specific molecules.
As an example, a protein that moves calcium won’t be able to move glucose. Each of the cells of your body is home to hundreds of the membrane proteins.
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