Problem 7

Background and context

The plasma membrane is a phospholipid bilayer that surrounds the plant and animal cells. It is embedded with several proteins, carbohydrates, glycolipids, and glycoproteins. The plasma membrane is selectively permeable in the sense that it allows the entry and exit of specific molecules in and out of the cell. 

The phospholipid bilayer is made up of two layers of lipids. Each lipid contains a hydrophobic tail and a hydrophilic head. The bilayer is formed as the hydrophobic tails face the inner side of the bilayer and form a hydrophobic region held by the intermolecular forces between tails. The membrane fluidity can be defined as the movement of the membrane because of the viscosity of phospholipid composition.