Question

Restriction endonucleases are utilised in genetic engineering techniques as

• A. Molecular cement for combining DNA bits into long chains
• B. Molecular scalpels for cutting DNA at specific sites
• C. Molecular scalpels for cutting DNA break up
• D. Molecular build up nucleotides in tandem

Answer 1

The correct option is B Molecular scalpels for cutting DNA at specific sites

Restriction endonucleases are enzymes, isolated chiefly from prokaryotes, that recognize specific nucleotide sequences within double stranded DNA and cleaves it at these sites. These restriction endonucleases facilitate the specific fragmentation of double stranded DNA and are very useful for DNA sequence analysis. These enzymes can be classified into three groups. Type I and type III enzymes carry a modification (methylation) and an ATP requiring restriction (cleavage) activity within the same protein. Both types of enzymes identify unmethylated sequences in substrate DNA, but type 1 enzymes cleave randomly, whereas type III enzymes cut DNA at specific sites. Type II restriction enzyme consist of a separate restriction endonuclease and a modification methylase. Hence, restriction endonucleases are also known as molecular scalpels or scissors for cutting DNA.

Therefore, the correct answer is option B.