Chapter 20, Problem 1TYK

Summary Introduction

To review:

The functions of restriction endonucleases.

Introduction:

The nucleases are the enzymes that cut the nucleic acid chains into smaller fragments. The restriction endonuclease is the type of nuclease enzymes found in bacteria. These enzymes have the capability to cleave the DNA (deoxyribonucleic acid) molecule at specific sites.

Explanation of Solution

Restriction endonuclease enzymes recognize a particular sequence within the genome. The specific sites recognized by these enzymes are called recognition sites. They cut the DNA at the site same as the recognition site or at any other site. The site where the DNA is cleaved is called the restriction site.

The DNA fragments produced after the cleavage by restriction enzymes are called restriction fragments. These enzymes are a part of defense mechanisms in bacteria. The DNA of viruses, which invade the bacteria, is cleaved by the restriction enzymes, and thus, the viral infection in bacteria is prevented.

The restriction endonucleases are used in the biotechnological applications. Biotechnology is the branch of biology that deals with manipulation of DNA sequences in organisms to obtain desired biological product. Restriction endonucleases are the tools used by biotechnologists to isolate specific DNA sequences from the organisms and introduce them into other organisms in the laboratory to obtain new combinations of DNA known as recombinant DNA molecules.

Conclusion

The restriction endonucleases cleave the DNA at specific sites. The fragments produced by restriction can be used for cloning purposes to obtain recombinant DNA molecules. This enzyme also provides a defense to the bacteria against viral infection.