CUET Preparation Today
Restriction endonucleases are used as molecular__________. |
molecular build up at nucleotides molecular cement to join DNA sites molecular knife cut DNA at specific site molecular degradation to break up the DNA to nucleotides |
molecular knife cut DNA at specific site |
The correct answer is Option (3) -molecular knife cut DNA at specific site Restriction Endonucleases (Molecular Scissors): These are enzymes that are commonly referred to as "molecular scissors" because they cut DNA molecules at specific recognition sequences. These recognition sequences are often palindromic, meaning the sequence reads the same forwards and backward. When a restriction endonuclease encounters its specific recognition sequence on a DNA molecule, it cleaves the DNA at that specific point by breaking the sugar-phosphate backbone of both DNA strands. This results in the production of DNA fragments with "sticky ends," which can be used in various molecular biology techniques like DNA cloning. Restriction enzymes belong to a larger class of enzymes called nucleases. These are of two kinds; exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA. Today we know more than 900 restriction enzymes that have been isolated from over 230 strains of bacteria each of which recognise different recognition sequences. The first restriction endonuclease is –Hind II. EcoRI and Hind III are also restriction endonuclease .EcoRI comes from Escherichia coli RY 13. |
