First restriction endonuclease enzyme was-

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UP TGT Biology 2011 Official Paper

Answer 1

Concept-

Restriction enzymes belong to a larger class of enzymes called nucleases.
Restriction enzymes are used to break DNA molecules.
Restriction enzymes are of three types- Exonuclease, endonuclease, and restriction endonuclease.
- Exonuclease- They cut off nucleotides from 5' or 3' ends of DNA molecule.
- Endonuclease- They break DNA duplex at any point except the end.
- Restriction endonuclease- They cleave DNA duplex at specific points.

Explanation-

Restriction endonuclease was found by Arber.
They act as "molecular scissors".
They recognize the base sequence at palindrome sites in the DNA duplex and cut its strands.
Hind II, whose functioning depended on a specific DNA nucleotide sequence was isolated.
It was found that Hind II always cut DNA molecules at a particular point by recognizing a specific sequence of six base pairs.
This specific base sequence is known as the recognition sequence for Hind II.

The first restriction endonuclease-Hind II.

Additional Information

Name	Recognition sequence	Source
EcoRI		Escherichia coli-containing drug resistance plasmid RI.
Bam I		Bacillus amyloliquefaciens
Hae III		Haemophilus aegyptius
Hind III		Haemophilus influenzae