Ethanol is used in the DNA isolation process because it primarily:

• A. neutralizes the negative charges on DNA by providing positively charged ions
• B. denatures DNA by breaking phosphodiester bonds in the sugar-phosphate backbone
• C. reduces DNA solubility, causing DNA to precipitate out of the aqueous solution
• D. selectively digests proteins and RNA while leaving DNA intact

Answer: (C)

Verified step by step guidance

1. Understand the role of ethanol in DNA isolation: Ethanol is used to precipitate DNA from an aqueous solution.
2. Recall that DNA is negatively charged due to its phosphate backbone, which makes it soluble in water.
3. Ethanol reduces the solubility of DNA by decreasing the dielectric constant of the solution, which weakens the interaction between DNA and water molecules.
4. This reduction in solubility causes DNA molecules to aggregate and precipitate out of the solution, allowing them to be separated by centrifugation.
5. Note that ethanol does not neutralize DNA charges by providing positive ions, nor does it break phosphodiester bonds or selectively digest proteins or RNA.