Question

Discuss how bacterial and archaeal DNA is organized, as compared to eukaryotes. Explain the application of plasmids and restriction endonucleases in genetic engineering, with examples.

Answer 1

The organisation of DNA in bacteria and archaea as compared to DNA in eukaryotes is as follows:-

• The bacterial and archaeal DNA do not contain membrane-vound nuclei that are present in eukaryotes.
• DNA in bacteria and archaes are present in the free form in the nucleoid while DNA in eukaryotes is present in the compact form inside the nucleus.

Plasmids can be transferred from one bacterium to another. For example, Ti andRi plasmids are used for genetic transformation in the plant system They are used to generate recombinant DNAs in genetic engineering and to transfer genes between different organisms. They contain genes that are not present in the main chromosome of bacteria. Therefore, they can be used to add extra genes without disturbing the rest of the genome of an organism.

Restriction endonucleases are enzymes that can be used for gene manipulation for different scientific appilcations. For example, EcoRI digest double stranded DNA at a specific sequence and give rise to sticky ends. They are used to digest genomic DNA for gene analysis through Southern blot.