What is the function of the fluid mosaic model?

The fluid mosaic model is a model used to describe the cell membrane and the transport of molecules through it. It is a semi permeable membrane which means that it is selective in the molecules that it allows to pass through. If molecules are over a certain size, they require the use of a carrier protein, which acts as a channel to allow the larger particles to pass through into and out of the cell. There is both passive and active transport within the fluid mosaic model. Passive transport does not require energy, and is simply the diffusion of small molecules such as oxygen. Active transport requires the use of carrier proteins and ATP (adenosine triphosphate). ATP is the energy driver of the cell.An example of active transport is the sodium potassium pump in which per ATP molecule that the pump uses, three sodium ions are exported and two potassium ions are imported leading to an overall net positive export.an important feature of the sodium potassium pump is that it pumps the two molecules against their concentration gradient (Hence ATP is required).The fluid mosaic model is composed of lipids which are hydrophobic, meaning that they are repelled by water. The hydrophobic heads face outwards whereas the hydrophilic phosphate tails face inwards. There are also carbohydrates and cholesterol within the membrane which respectively add to the energy stores of the cell and maintain the fluidity of the membrane.