Bitechnology : Principles and Processes Biology Quiz for NEET

Restriction enzymes belong to a larger class of enzymes called Nucleases.

Nucleases are of two different kinds :Exonucleases which remove nucleotides from the end of a DNA molecule, Endonucleases, which break internal phosphodiester bonds at palindromic sites that are highly specific

DNA ligase helps in joining DNA fragments

During the isolation of desired gene, chilled ethanol is used for the precipitation of DNA.

Restriction enzymes cut DNA molecules at a particular point by recognising a specific sequence. Each restriction endonuclease functions by inspecting the length of a DNA sequence. Once it finds its specific recognition sequence, it will bind to the DNA and cut each of the two strands of the double helix at specific points in their sugar-phosphate backbone.

This technique is used for making multiple copies of gene of interest in vitro. Each cycle has three steps (1) Denaturation (2) Primer annealing (3) Extension of primer

Refer NCERT BOOK Class 12th Page No.202 (Fig.11.6)

In recombinant DNA technology, selectable markers helps in identifying and eliminating non-transformants and selectively permitting the growth of the transformants.

DNA fragments are negatively charged because of phosphate group.

Ethidium bromide is used to stain the DNA fragments and will appear as orange coloured bands under UV light. (Refer Class 12th Page-198 Fig.11.3 )

During gel electrophoresis, DNA fragments separate according to their size through sieving effect provided by agarose gel.

In DNA recombinant technology, linking of foreign DNA and plasmid is made possible by DNA ligase which is also called “molecular glue”.

It cuts the DNA in the centre of restriction site

Plasmid is extrachromosomal, double stranded circular DNA.

Taq polymerase is thermostable DNA polymerase obtained from Thermus aquaticus.

Restriction enzymes is called molecular scissors or knife.

In some case ( To keep the cultures free of infection ) this option may be correct