Question

Multiple Choice, Please answer all 4

What is the purpose of the neutralization solution when purifying plasmid DNA?

		precipitates plasmid DNA
		lyses the cells
		contains a detergent
		precipitates chromosomal DNA and proteins

Why does the DNA bind to the purification resin?

		the resin is negatively charged
		the resin is hydrophobic
		the resin is positively charged
		the resin is neutral

Why did you get colonies on plate A but not on B in the transformation, even though both plates had ampicillin?

		bacteria on A were transformed with plasmid which carries ampicillin
		bacteria on A were transformed with plasmid which destroys ampicillin
		plate A contained arabinose which provides nutrition for the bacteria
		plate B contained arabinose which kills the bacteria

Why do the colonies on plate A glow under UV light?

		the GFP gene makes a protein which glows
		the ampicillin resistance gene makes bacteria glow
		arabinose makes bacteria glow
		anything you put over a UV light box will glow

Answer 1

1. Neutralization solution precipitates bacterial chromosome and proteins.. Generally sodium hydroxide is used as neutralization solution.

Plamid occurs in supercooled confirmation while chromosomal DNA in linear form .Addition of solution breaks the hydrogen bonds of linear chains seperating them into two polynucleotide chains which furthur on adding acid gets aggregated and seperated by density centrifugation.Supercoiled conformation of plasmid are not affected by the neutralizing solution.

2. Dna exist as negatively charged molecules. For their chromatographic seperation we will need Anion exchange resins which have positive charge groups attached to matrix.

3. Bacteria on plate A must be transformed by ampicillin resistance gene i.e able catabolize the ampicillin present in the growth media

Bacteria on A are transformed by plasmid which destroy ampicillin.

4.Ampicillin resistant gene make the bacteria glow.