LIFE SCIENCE

Detailed explanation-1: -Restriction enzymes are also called “molecular scissors” as they cleave DNA at or near specific recognition sequences known as restriction sites. These enzymes make one incision on each of the two strands of DNA and are also called restriction endonucleases.

Detailed explanation-2: -Sticky ends are helpful in cloning because they hold two pieces of DNA together so they can be linked by DNA ligase.

Detailed explanation-3: -The first step in the development of recombinant DNA technology was the characterization of restriction endonucleases-enzymes that cleave DNA at specific sequences. These enzymes were identified in bacteria, where they apparently provide a defense against the entry of foreign DNA (e.g., from a virus) into the cell.

Detailed explanation-4: -The discovery of enzymes that could cut and paste DNA made genetic engineering possible. Restriction enzymes, found naturally in bacteria, can be used to cut DNA fragments at specific sequences, while another enzyme, DNA ligase, can attach or rejoin DNA fragments with complementary ends.