O Band B DNA is more supercoiled than band A DNA. Topoisomerase l supercoiled ba
ID: 214118 • Letter: O
Question
O Band B DNA is more supercoiled than band A DNA. Topoisomerase l supercoiled band B DNA and topoisomerase lI supercoiled band A DNA. Band B DNA is less supercoiled than band A DNA Band B DNA is negatively supercoiled, whereas band A DNA is O positively supercoiled Q Relaxed DNA is more susceptible to DNA damage, resulting in two populations of DNA size groups. Scroll down for feedback. How would the addition of DNA ligase and DNA gyrase to the plasmid sample prior to electrophoresis alter the migration pattern? A new band will appear between the original A and B bands Band B will disappear The linking number of the DNA ill increase. The migration pattern will change from discrete bands to a smear of many species. Band A will disappearExplanation / Answer
1. Correct answer is: Band B DBNA is more supercoiled than Bnad A DNA.
This is because, the migration of a supercoiled DNA in an agarose gel, follows a different pattern. The DNA which is supercoiled, becomes samller in size, than an open circular DNA or a linear DNA. This gives faster motolity to the DNA in an agarose gel. when a DNA becomes open circular or llinear, it experiences more frictional resistance on the gel and thus the movement becomes slower.
Therefore, more supercoiled DNA, because of experiencing less frictional resistance, moves faster in the gel and travels a greater distance. Thus irt confirms that band B DNA is more supercoiled than band A DNA.
2. The migration pattern will change from discrete bands tpo a smear of many species.
Since DNA gyrase opens the supercoiling in a DNA and due to open supercoiles, there may generate nicks in the DNA. this will cause smear of bands in the agarose gel.
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