Multiple Choice
In recombinant DNA technology, DNA ligase is used to rejoin which of the following bonds in DNA?
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17. Mutation, Repair, and Recombination
DNA Repair
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During the DNA isolation process, which reagent is commonly used to stabilize DNA and prevent its degradation?
A
EDTA, by chelating divalent cations required for nuclease activity
B
Ethanol, by precipitating DNA from solution
C
Phenol, by separating proteins from nucleic acids
D
SDS, by denaturing proteins and lysing cell membranes
Verified step by step guidance1
Understand the role of each reagent in the DNA isolation process: EDTA, Ethanol, Phenol, and SDS each have distinct functions.
Recall that nucleases, enzymes that degrade DNA, require divalent cations such as Mg^{2+} or Ca^{2+} to function properly.
Recognize that EDTA acts by chelating (binding) these divalent cations, effectively removing them and thereby inhibiting nuclease activity to protect DNA from degradation.
Compare this with other reagents: Ethanol is used to precipitate DNA, Phenol separates proteins from nucleic acids, and SDS denatures proteins and lyses cell membranes.
Conclude that the reagent responsible for stabilizing DNA and preventing its degradation during isolation is the one that chelates divalent cations, which is EDTA.
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