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Question: Term ‘Restriction’ in restriction endonuclease enzyme refers to A. Cleaving of the phosphodiester ...

Term ‘Restriction’ in restriction endonuclease enzyme refers to
A. Cleaving of the phosphodiester bond in DNA by the enzyme
B. Cutting of DNA at specific positions only
C. Prevention of bacteriophage multiplication in bacteria
D. Cutting each of the two strands of DNA at a specific point in the sugar-phosphate backbone

Explanation

Solution

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.

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. Restriction site is the particular site on DNA molecules that contains specific sequences of nucleotides. Restriction sites are also called restriction recognition sites. Restriction sites are generally palindromic sequences. 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. Therefore, the term restriction in restriction endonuclease enzyme refers to the cutting of the two strands of DNA at a specific point in the sugar-phosphate backbone.
So, option D is the correct option.

Note: Types of restriction enzymes are type I, type II, type III, type IV, and type V. Artificial restriction enzymes are also available. 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.