Answer to Question #119093 in Molecular Biology for Great

Question

Elucidate two physical properties that will enable you to isolate TOL plasmid from the chromosomal DNA of the bacteria.

Answer 1

Two physical properties of TOL plasmid that enable its isolation from the chromosomal DNA of the bacteria include size and supercoiling. The size of the TOL plasmid is approximately 115,000 bases while the size of the chromosomal DNA is around 6 mln bases. As plasmid DNA has a smaller size, it is characterized by a lower melting point. As a result, the plasmid can obtain its normal double-stranded organization after complete melting faster and more accurately than large chromosomal DNA. Next, as the plasmid is supercoiled, its size is smaller compared to large chromosomal DNA. This feature also facilitates rapid renaturation of plasmid DNA following alkaline-induced denaturation of DNA. As TOL plasmid is smaller in size compared to chromosomal DNA, it undergoes renaturation more efficiently than chromosomal DNA facilitating its isolation.