Q1: Why does the alcohol need to be very cold for this to work?
A1: DNA is soluble in water but not in alcohol especially in the presence of salt. It is even less soluble in cold alcohol which allows for better precipitation of the DNA.
Q2: Can you use this method to extract DNA from other fruits? Vegetables?A2: All fruits and vegetables have DNA but some will work better than others especially using this crude “kitchen” lab. Most cells are diploid, which means they have two sets of chromosomes but some crops are actually polyploids meaning they have more chromosomes. Strawberries are actually octoploids (8 chromosomes) so they yield a lot of DNA for a small amount. You also need to work with something that is easily liquified. After strawberries, kiwi and bananas (no peel for those) are your best bets.
Q3: What can you do with the DNA goop once you’ve got it? (it is currently labeled and stored in a small plastic container) Could you do anything with the DNA? A3: Unfortunately, without special reagents and equipment there is not much you can do with the DNA. In a lab, that DNA would be purified more and then could be sequenced, compared to other DNA from other strawberries or plants, cloned, and many other things.