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Remote Ready Biology Learning Activities has 50 remote-ready activities, which work for either your classroom or remote teaching.
The answer
The truth is that neither alcohol has a temperature requirement and both will work at room temperature or ice-cold. The reason behind this is that DNA is soluble in water, which is why it can't be seen in the buffer. However, DNA is insoluble in alcohol, so as one adds alcohol, the DNA that floats into this layer will become visible as it is not dissolved in solution. It is recommended to chill both isopropyl and ethyl alcohol because all solids and liquids become less soluble in colder temperatures. This makes the DNA even more poorly soluble in the alcohol layer, allowing more to precipitate. I will add, however, that the amount that is gained by chilling the alcohol is trivial and the chilling need not be done. The amount of DNA you get is huge no matter what you do.