Upon exposure to insecticides, insects that do not carry the resistance genes die, thus allowing the individuals with the resistance genes to survive and reproduce, creating more resistant insects. With every generation the number of resistant insects increase.
The cell membrane is comprised of a phospholipid bilayer that remains interspersed with protein molecules.
Each phospholipid molecule is comprised of:
A glycerol molecule linked with the help of ester bonds to,
one phosphate group,
two fatty acid (saturated or unsaturated) molecules.
Being hydrophilic in nature, the phosphate group faces outside the lipid bilayer forming hydrogen bonds with the water molecules.
Being hydrophobic in nature, the fatty acid molecules faces to the interior of the bilayer avoiding contact with water and forming hydrophobic interactions with each other.
The saturated fatty acid molecules have a straight hydrocarbon chain as they lack any double bonds. However, the unsaturated fatty acid molecules possess multiple double bonds that generate a kink or bent in their structure. The kink causes the molecules to occupy more space in the bilayer and also help these molecules to move laterally about their position, thereby generating fluidity in the membrane.
The lateral movement of the lipid molecules also causes the lateral movement in the interspersed protein molecules.
The interspersed protein molecules has various functions like, they act as channel proteins, carrier proteins, receptor proteins, etc.
