Question

Arrange the following in sequential order of their usage in recombinant DNA technology.

I) Calcium chloride
II) DNA ligase

III) Ethylenediaminetetracetic acid

IV) Restriction endonuclease

• A. (I), (IV), (III), (II)
• B. (IV), (I), (II), (III)
  
• C. (I), (IV), (II), (III)
  
• D. (III), (IV), (II), (I)
  

Answer 1

The correct option is D (III), (IV), (II), (I)

• Recombinant DNA technology includes techniques for the creation of recombinant DNA which carries DNA from two different sources.
• It includes isolation of target DNA, cutting of DNA at precise locations using restriction endonucleases, selection of a small molecule of DNA that can self-replicate, called cloning vectors, insertion of DNA with the gene of interest in vector DNA to make recombinant DNAs, insertion of recombinant DNA to a host cell that will provide the enzymatic machinery for DNA replication and selection of host cells that contain recombinant DNA.
• Thus, among the given options, EDTA is first used to drive the lysis of bacterial cells to isolate target DNA and vector molecule.
• Then, restriction enzymes (IV) are used for cutting the desired DNA sequence followed by use of DNA ligase (II) enzyme to join the desired gene sequence with vector DNA and the recombinant DNA molecule is produced.
• This is followed by the insertion of recombinant DNA into the host cell, for which calcium chloride (I) mediated gene transfer technique can be used.

Hence, the correct answer is option D.