Science Buddies: "Ask an Expert"

My 3rd grader and I have followed the protocol kindly suggested here https://www.sciencebuddies.org/science- ... shtml#help. We did one attempt where we crushed the strawberries very well in the plastic bag, and then added only water (no salt or detergent)- as a "negative control" for the extraction. In our "negative control" we could still see a whitish precipitate when we added alcohol- is it likely that this was also DNA, and that we had mechanically lysed enough cells to get this result without adding salt and detergent?
Thank you for any insight!

It's possible. It's also possible that it is salt or sugar from the strawberries themselves. Does it look the same as the precipitate you get with salt/detergent?

Thank you for your reply!
It really looked like DNA, it was white and "cottony", and we could spoil it on to a skewer when we added alcohol. When we used salt and detergent there was more "cotton" formed, but this also had a hint of pink color (guessing it was pretty contaminated).

So, given that there was less DNA-like material in the absence of salt/detergent could your child come up with a hypothesis to explain this? This would be a good exercise and a point to include in the interpretation of the results.

Cheers,
Colin