Plasma membrane is a semipermeable membrane surrounding the cytoplasm, and is mainly made up of proteins, lipids (phospholipids and cholesterol) and carbohydrate groups.
In humans, proteins are about 50% composition of the plasma membrane, lipids (of all types) are 40%, and the remaining 10% are carbohydrates.
Phospholipids are a type of lipid having 2 fatty acid chains attached to a head, containing a phosphate group and glycerol.
The phospholipid bilayer (2 layers of phospholipids) have different types of proteins embedded in it.
The proteins are of various types – transmembrane proteins, integral proteins, glycoprotein.
Cholesterol is a type of 4 ringed lipid molecule present in the core of the biological membrane, next to the phospholipids.
Carbohydrates of a plasma membrane are linked to protein or lipid molecules, forming glycoproteins and glycolipids, respectively. These are present on the outer surface of the membrane.
Final Answer –
The plasma membrane is primarily composed of lipids, proteins and carbohydrates.