Question

Describe the structure of the plasma membrane of a cell. Incorporate the job of phospholipids and proteins. What is implied by the expression "Fluid Mosaic Model"

Answer 1

The plasma membrane is the structure that covers and protects the cell.The plasma membrane is composed of lipids,proteins and carbohydrates thet are well arranged to provide it integrity and strength.The structur of the plasma membrane is called the fluid mosaic model.

According to this model proposed in 1972,

the plasma membrane is a mosaic which consists primarily of the  phospholipids, cholesterol, and proteins.The major component of the plasma membrane is the phospholipids.They are arranged in a bilayer that forms the main part of the membrane.The hydrophilic part of the phospholipids are faced outwards while the hydrophobic ends are faced inwards protecting them from the water.This arrangement of the phospholipids forms a good barrier, because water and other polar or charged substances cannot easily cross the hydrophobic core of the membrane.

The second major component is the proteins.They are of 2 types,the peripheral proteins and the integral proteins.

The integral proteins are embedded inside the membrane and have the hydrophilic end exposed outside and the hydrophobic end to the inside.Meanwhile the peripheral proteins are loosely arranged.These proteins act as the ion channels and the transporters that transport substanaces acreoss the membrane

The carbohydrates are seen in the outside and they forms the receptors that are esssential in the cell recognition