Question

Which one of the following is a restriction endonuclease?
A. Hind II
B. Protease
C. DNase I
D. RNase

Answer 1

Hint: It is a type II restriction enzyme found in Haemophilus influenzae. Type I, II, III and IV are the four classes of restriction endonucleases. The natural sources of restriction endonucleases are bacterial cells.

Complete step by step answer:
Hind II is a type II restriction enzyme. Restriction enzymes are traditionally classified into four types on the basis of subunit composition, cleavage position, sequence specificity and cofactor requirements. Bacterial infection is restricted by certain viruses and that is why they are called as restriction enzymes. Their function in the bacterial cell is to destroy foreign DNA they might enter the cell. They have the capacity to recognize the specific base sequences on the DNA and then cut each strand at a given place. Restriction endonuclease is also called a molecule scissors. The most user aspect of restriction enzymes is that each enzyme recognizes the same unique base sequence regardless of the source of the DNA.it means that these enzymes establish fixed landmarks along an otherwise very regular DNA molecule. This allows dividing a long DNA molecule into fragments that can be separated from each other by size with the technique of gel electrophoresis. One of the most popular restriction enzymes is called Eco RI from E. coli (bacterium).
The correct answer is option A. i.e., Hind II.

Note: Restriction enzyme also called restriction endonucleases is protein produced by bacteria that cleaves DNA at specific sites along the molecule. Restriction enzymes can be isolated from bacterial cells and used in the laboratory to manipulate fragments of DNA such as those containing genes for this reason, they are indispensable tools of recombinant DNA technology.