DNA Extraction. Strawberries. How much DNA would I get?
Please…?
Directly from the fruit itself? Not much. But you could use PCR to grow that into as much as you want.
Also, what kind of DNA would you be extracting? There isn’t much dinosaur DNA in a strawberry.
There are several companies that make nucleic acid extraction kits for virtually any kind of sample. For the large-scale extraction of genomic DNA from plant matter, one product claims a yield of 30 to 260 micrograms of DNA per gram of wet weight.
From the manual (PDF):
Based on this, I assume that strawberries are a particularly bad choice.
Strawberries are almost totally water, by weight, as you’ll know if you’ve eaten cereal with freeze-dried strawberry pieces in.
Well, I say almost totally. Googling suggests something like 92%. So you can discount that straight away.
Are you talking about the home/middle-school lab ‘extraction’ demonstration where you basically precipitate DNA in alcohol?
If so, then in my experience, you get visible filaments, but not a whole lot of mass. I’d say four or five berries for one test tube, and way less than a gram of actual precipitate; I could only make wild guesses at anything more precise.
It’s a fun demo, BTW; cool biochemistry with just a blender, dish soap, meat tenderizer and concentrated ethanol, but hardly high-precision lab work.
The “high-precision lab work” version ain’t much different, at least in the early steps. Mash up your sample, add a bit of detergent, get rid of the solids, and precipitate in alcohol. But the next few cleanup steps in that sort of method involve some rather nasty chemicals – I certainly wouldn’t want to give chloroform to a bunch of 13 year olds.
The strawberry genomeis about 240 million basepairs, and the common strawberry is an octoploid hybrid. The average weight of a double strand DNA basepair is about 1x10^-9 picograms. So the DNA content of a single strawberry cell is 8 * 2.4x10^6 * 1x10^-9 = ~1.9 picograms.
From this source, there was around 3x10^6 cells in a 15 g fruit. This seems very low to me, but if it’s correct there would be 5.8 micrograms of DNA total, or .38 micrograms per gram of fruit.
This is a pretty standard homework question I see a lot on other sites. Doing DNA extraction from strawberries is apparently a common lab experiment done in high school nowadays, and students often appear to be unwilling to go to the trouble of figuring out the answer for themselves.