Ethanol (CH3-CH2-OH) is miscible in water because it is able to form hydrogen bo

Question

Ethanol (CH3-CH2-OH) is miscible in water because it is able to form hydrogen bonds with itself and other molecules. However, its structure only allows it to form 1-2 hydrogen bonds. This is one reason why even low concentrations of ethanol in solution are lethal for cells.

Based on this information, explain why we can use high concentrations of ethanol to precipitate DNA out of solution.

Also, describe/predict the effects of increasing concentrations of ethanol in (and around) a cell on macro-molecular interactions (i.e. on weak bonds).

It is possible to select for yeast that are tolerant to increased concentrations of ethanol. Give an example of a physiological change in yeast cells that might make them resistant to ethanol.

Explanation / Answer

Ethanol precipitation of DNA

DNA is polar due to its heavily charged phosphate backbone. The polarity is based on the principle of "like dissolves like", making it soluble in water, which is also excessively polar. Because of the high polarity of water, illustrated by its high dielectric constant of 80.1 (at 20

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