Question

Restriction endonucleases, in DNA fingerprinting, carries out the following process
A) Fragmentation of DNA
B) Getting copies of DNA
C) Loading DNA on agarose plate
D) Synthesis of DNA

Answer 1

Hint: Restriction endonucleases play a major role in recombinant DNA technology techniques. These enzymes are capable of recognising specific sites on the DNA and carry out cleavage at those sites. These sites are known as restriction sites and each enzyme is specific for a given site. These enzymes are found in bacteria and archaea and provide them with a defence mechanism against viruses. Nowadays these enzymes are isolated in laboratories and used as a vital pool in many molecular biology techniques.

Complete Answer:
- The cleavage caused by restriction endonuclease is brought about by making cuts in the sugar-phosphate backbone of DNA.
- There are four different types of naturally occurring restriction endonucleases- type I, II , III and IV.
- There lies considerable variation among the four types in recognition sites, subunit composition, cleavage position and also cofactor requirements. Restriction endonucleases play a major role in DNA fingerprinting.
- DNA fingerprinting is an important technique that is based on the principle that all people's DNA is different. This technique is widely used to catch criminals. Restriction enzymes function to cut DNA into fragments.
- DNA of all people consists mostly of the same sequence except in case of Short Tandem Repeats(STR). STR number varies from one person to another and this is what makes every person’s DNA unique.

So the correct answer is A) fragmentation of DNA.

Note: As stated above DNA fingerprinting helps to catch criminals. First the DNA from the suspects is collected. They are then fragmented and these fragments are compared to the DNA obtained at the crime site at STR region. If the STR region matches then the suspect is identified as the criminal.