LIFE SCIENCE

Detailed explanation-1: -Introduction. 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: -SmaI is an example of a restriction enzyme that cuts straight through the DNA strands, creating DNA fragments with a flat or blunt end. Other restriction enzymes, like EcoRI, cut through the DNA strands at nucleotides that are not exactly opposite each other.

Detailed explanation-3: -Restriction enzymes are proteins produced by bacteria to prevent or restrict invasion by foreign DNA. They act as DNA scissors, cutting the foreign DNA into pieces so that it cannot function.

Detailed explanation-4: -Restriction endonuclease was isolated for the first time by W. Aber in 1962 in bacteria. Restriction endonucleases cut the DNA duplex at specific points therefore they are also called as molecular scissors or biological scissors. Three types of restriction endemicleases are Type 1.