Question

Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product is produced.

Answer 1

Hint: The nucleic acid present in the cell is called DNA. It is the genetic material of an organism. The enzyme which cleaves the DNA into fragments at a particular restriction site is called a restriction enzyme. Restriction enzymes are also called endonuclease or restrictase.

Complete answer: The term DNA stands for deoxyribonucleic acid. The structure of DNA is coiled helical in shape which consists of two polynucleotide chains. DNA carries the genetic instruction for the functioning, development, reproduction, and growth of all known organisms and also many viruses. Therefore, DNA is considered the genetic material of an organism. The whole DNA molecule is cleaved or broken into small fragments at a particular site called a restriction site. The enzyme that is used for the purpose of cleavage is called a restriction enzyme. Types of restriction enzymes are type I, type II, type III, type IV, and type V. Artificial restriction enzymes are also available. Restriction site is the particular site on DNA molecules that contains specific sequences of nucleotides. These nucleotides are recognized by the restriction enzymes. Restriction enzymes make two incisions to cut the DNA molecule on each strand of the sugar-phosphate backbone. Recognition sequences are further classified depending on the number of bases in its recognition site which is usually between 4 and 8 bases. Here in the given diagram restriction enzyme, BamH1 is used to cleave DNA at the GGATCC restriction site. After cleaving the DNA at the G nitrogen base of the restriction site, sticky ends of DNA substrate are formed.

Note: Restriction site is also called a restriction recognition site. Restriction sites are generally palindromic sequences. Isolated restriction enzymes are used for the purpose of DNA manipulation. During the process of gene cloning, restriction enzymes are used for inserting the gene into the cloning vector.