Biotechnology- Principles and Processes Question 48
48. DNA precipitation out of a mixture of biomolecules can be achieved by treatment with:
[2019]
(a) Isopropanol
(b) Chilled ethanol
(c) Methanol at room temperature
(d) Chilled chloroform
Show Answer
Answer : b
Hints & Solutions
(b) During the isolation of desired gene, chilled ethanol is used for the precipitation of DNA. Ethanol is used in DNA extraction to force the DNA to precipitate in a solution. In order to collect a DNA sample, cells are broken down through agitation, and then mixed with water, salt and ethanol to create an aqueous solution. Ethanol along with salt work to prevent the DNA from dissolving into the water, instead causing it to precipitate out so it can be separated and extracted using a centrifuge. Since DNA is insoluble in ethanol and isopropanol, the addition of alcohol, followed by centrifugation, will cause the DNA proteins to come out of the solution. When DNA concentration in the sample is heavy, the addition of ethanol will cause a white precipitate to form immediately.
