Yummy strawberries have lots of DNA
Syndicated from thetech.org “Do-it-yourself Strawberry DNA”
Strawberries, bacteria, humans—all living things have genes, and all of these genes are made of DNA. That’s why scientists can take a gene from one living thing and put it into another. For example, they can put human genes into bacteria to make new medicines.
How do scientists take DNA out of a living thing? It’s not that hard—there are lots of ways to do it! You can follow the directions in the video below to get DNA out of a strawberry. Or you can follow the steps after that. Either way you’ll have strawberry DNA at the end!
What you need:
- measuring cup
- measuring spoons
- rubbing alcohol
- 1/2 teaspoon salt
- 1/3 cup water
- 1 tablespoon Dawn dishwashing detergent
- glass or small bowl
- cheesecloth
- funnel
- tall drinking glass
- 3 strawberries (green tops removed)
- reclosable plastic sandwich bags
- test tube or small glass jar (like the kind spices come in)
- bamboo skewer or kabob sticks (find them at the grocery store)
What to do:
- Chill the rubbing alcohol in the freezer. (You’ll need it later.)
- Mix the salt, water, and Dawn detergent in a glass or small bowl. Set the mixture aside. This is your extraction liquid.
- Line the funnel with the cheesecloth, and put the funnel’s tube into the glass.
- Put the strawberries in the plastic bag and push out all the extra air. Seal it tightly.
- With your fingers, squeeze and smash the strawberry mixture for 2 minutes.
- Add 3 tablespoons of the extraction liquid you made in Step 2 to the strawberries in the bag. Push out all the extra air and reseal the bag.
- Squeeze the strawberry mixture with your fingers for 1 minute.
- Pour the strawberry mixture from the bag into the funnel. Let it drip into the glass until there is no liquid left in the funnel.
- Throw away the cheesecloth and the strawberry pulp inside. Pour the contents of the glass into the test tube or small glass jar so it is 1/4 full.
- Tilt the test tube or jar and very slowly pour the cold rubbing alcohol down the side. The alcohol should form a layer on top of the strawberry liquid. (Don’t let the alcohol and strawberry liquid mix. The DNA collects between the two layers!)
- Dip the bamboo skewer into the test tube where the alcohol and strawberry layers meet. Pull up the skewer. The whitish, stringy stuff is DNA containing strawberry genes!
You can try these steps to purify DNA from lots of other living things. Grab some oatmeal or kiwis from the kitchen and try it again! Which foods give you the most DNA?
Here is a link to troubleshooting tips and FAQ list from the “Extract DNA from Anything Living” experiment: 20 Most Frequently Asked Questions
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DIYbio 
Pretty easy, must try.
I was surprised the other day to try out a 23andme kit — they have you spit in a tube and then add their detergent/soap solution to the sample, shake, and send it off! Same thing as this experiment!
What things can you do with the DNA now that you have extracted it?
Hi Maria,
In the San Francisco DIYbio group, we extracted DNA and then tried to visualize it with gel electrophoresis. Didn’t work for us on our first attempt and it’s worth re-trying.
Tito
Hi Tito,
I hope you are doing well.
I am Norman and live in San Francisco.
May I ask you about your Lab? Is it an open one or closed. Because I am just starting to learn (still doing the reading), I would really like to do some “Wet Work”, please let me know.
Thanks,
Norman
Hey Norman — we don’t have a lab. As you can see, the soap + strawberry’s experiment doesn’t require anything complicated 🙂
(We’ve been holding our meetings at Noisebridge, which is a hackerspace in SF. )
Tito
its so cool!
She says “I don’t advise using your sister” as a source of DNA…but it is super easy to extract HUMAN DNA–I know because I just did it yesterday in about 20 minutes! There are easy “recipes” on the web.
So, when it comes to the thrill of extracting genetic material (and it is a thrill!), why not use oneself? (Or any one you know who is up for the adventure.) Seems more inspiring to me than using strawberries, kiwi or wheat germ.
Debra,
Could you link me to the “recipe” you used?
Hi JYouk,
For extracting human DNA, here’s a link to “5 minute DNA extraction in a shot glass” by Mac Cowell.
Why is it easier to extract DNA from strawberries? I did a science experiment on extracting DNA from green peas, strawberries, and grass to see which contained the most DNA. Strawberries did. But now I need an answer of why this is. PLEASE HELP! Thanks!
P.S. If you could also tell me why tomatoes didn’t work, I would appreciate it a lot!
Hi Chloe,
Great question! I’ve tried green peas, strawberries, and grass (and will make a guess about tomatoes).
In my experience, and from what I’ve read online, seeds are a great source of DNA. After all, seeds are for reproduction. Since DNA is a big component in reproduction, it makes sense that seeds should have lots of DNA relative to other parts of a plant like leaves and bark.
So, if we look at your experiments, strawberries, green peas, and tomatoes contain seeds, but grass doesn’t. This might explain why peas and strawberries had more DNA than grass. Did the pieces of tomato include the part with seeds? What would happen if you re-tried the experiment just using the tomato seeds, and not the rest of the tomato?
As for why strawberries had more DNA than peas, I’m really not sure. Are you a member on the DIYbio mailing list? It’s a great place to get more info and ask questions!
http://groups.google.com/group/diybio
Tito
Why would a seed cell contain more DNA?
Hi Splicer,
According to the following FAQ on “Extract DNA from Anything Living”, the cytoplasm of each seed cell is much smaller than a normal cell, but has the same amount of DNA. Overall, a seed cell will have approximately the same quantity of DNA as any other cell. However, since the seed cell are so much smaller, there are a lot more of them. That’s why you see a spoonful of peas contains more DNA than a chunk of bark. Or does it?
FAQ: http://learn.genetics.utah.edu/content/labs/extraction/howto/faq.html
I’ve appended this FAQ to my article.
Tito
The answer to Chloe’s question is more complicated than she probably realized. There three major factors that play into a successful DNA purification: (A) Initial quantity, (B) appropriate extraction buffers, and (C) technique. There is a lot of room for minutiae in the latter, so let’s discuss “initial quantity” first.
Initial quantity of DNA — the largest amount you could possibly obtain — is determined by the number of cells, the size of the genome, and the number of copies of the genome per cell (“ploidy”). The most common strawberry species cultivated in the United States is octoploid. This means each strawberry cell contains 8 complete copies of its genome. For comparison, somatic human cells are diploid, meaning we have 2 copies. Of course, genome size is important too. The strawberry genome is only 200Mbp (million base pairs) per copy, while the human genome is 3Gbp (billion base pairs) per copy. And then there’s number of cells, which has to do with the size of the cells (small = more cells per unit volume) and the size of the sample (big strawberry = more cells). Onions are also chock full of DNA, and would also make a great source of DNA for your first extractions.
The next major factor is the buffer formulation. In this case, we’re using Dawn, which is a cocktail of detergent and enzymes, to break open the strawberry cells. Strawberry pulp is mushy — not fibrous like wood or grass — because the cell walls contain very little cellulose. So, just a little detergent and some mashing with your fingers is enough to pop the cells open. In academic labs, we often resort to much harsher methods to get DNA out of some woody plants and fungi. If this recipe did not work as well for grass, peas or tomatoes, it could be because you did not do enough mashing to break the tougher cell walls.
= Try starting with frozen peas, since the water crystals probably already “popped” the cells.
– Or, try pulsing the peas + salt + water in a blender for 15 seconds.
– Tomatoes probably contain too much water, diluting your “DNA soup”. Try this same recipe without adding any water.
For a great tutorial on onions with household chemicals, check out this page:
http://biotech.biology.arizona.edu/labs/Murphy_onion.html
The link Tito contributed (above) has some great tips on proper “technique”, such as not stirring too much!
Cool link to extractng DNA from an onion, BioPhD!
Tito
hi its my fist time !!! I like to know what other biological materials could you use to extract DNA? , and what biological materials would not be good sourse of DNA?
Tito,
Unless you cut the DNA with restriction enzymes you won’t be successful in running the whole blob of DNA through the gel.
What do you think the result would look like if you ran the gel without a restriction enzyme?
Tito
If you ran the DNA from this protocol on, lets say
1: A 1% agarose gel (much lower percentage than that and the gel probably wont solidify)
2: For 1 hour at, lets say 100V (and as much current as it takes, though shouldnt be more than 100mA)
3: Visualized it with Ethidium Bromide (dangerous) and UV light (also dangerous)
Then you might see a large blob exactly where you loaded it.
If you have not introduced any degradation (by accident) of the DNA, then you would looking at some extremely large pieces of DNA. Probably the entire genome in a tangled mess.
With the proper restriction enzymes you might get some nice bands.
That’s a good point, Lasse. Would the blob of DNA move at all? Are the pieces of genome DNA really large or would the extraction protocol have cut everything into smaller (kb scale) pieces?
Secondly, Step #3 can be done safely with sybrSAFE dye and a blue light transilluminator, rather than the 2 components you mention.
Well tito the blob would move but you’ll have to variate the time of the electrophoresis and the amount of agar and the current, and it’s to complicated so for easier visualization it’s prefereble to cut it with res. enzymes.
It’s accurate that the extraction protocol will cut some of the DNA into pieces, but it depends on your skills to extract how small these pieces are going to be.
It’s possible that one could also shear genomic DNA into smaller pieces using high-frequency sound waves to vibrate the sample (this is called “sonication,” and typically requires a device called a sonicator). Perhaps there is some way of mimicking a sonicator’s functions at home, to shear DNA into smaller pieces. This still won’t produce distinct bands necessarily, but it would make the DNA more likely to migrate on the gel.
You could use a small syringe and 22-gauge (or smaller) needle to shear the DNA. These are cheap and relatively easy to get (although some might wonder if you’re an addict!;)
Suck it in and out of the syringe 20+ times and don’t do it gently. You’ll probably get bubbles but that’s OK. This is an effective way to shear DNA that’s still sometimes used in labs today. It should give you enough small fragments to enter an agarose gel. You’ll probably see a smear all the way down the lane. You’d see a smear with a restriction enzyme too, not individual bands, so the result is the same but easier/cheaper. Good luck.
So, can I use this to make my girlfriend taste like a strawberry? How would I do that?
joe, that it totally iimpossible. you cant make your girlfriend taste like a strawberry. unless you are going cover her with strawberry juice!
Hey guys, For those of you who remember the old DNAHack site it’s been archived here;
http://web.archive.org/web/20070420204234/http://www.dnahack.com/
I’m hoping a lot of the information on this site could eventually migrate to diybio someday.
Cool idea Brandan — do you know any of the admins/owners at DNAhack?
Tito
Hi tito
would it be possible to extract the dna from a blue flowering plant (eg a pansy) and insert it into a magnolia (seed or piece of tissue culture eg micropropagation) so that the new offspring would flower blue flowers? If so, do you know how to achieve this?
Thomas Edwards use to run DNAhack and the only mail leads I have are:
tedwards at the gmail.com
dorkbotdc at the dorkbot.org
He also runs a web site here. http://www.t11s.com/
i think that could use toilet tissue or klenex instead of cheese cloth to conduct this experiment.
i did this experiment in class. it was fun and i found out that the dna in the strawberries is very interesting. how the dna floats on the top of the tube.u should try this at home or in your science class!!!!
I LOVED IT! I found it very helpful in order to do my DNA project, I suggest not using a coffee filter because it’s harder to filter the strawberry “soup”.
Thank you,
Yasmeen
enjoyed this blog post!
after the DNA has migtated, how is it analyzed? Do you just look at the intensity, length and width of the band measurment to see if that berry type is octaploid, diploid.etc.?
Thats cool and all, but now I need to know how to put this DNA into a potatoe!!!!
what’s the function of salt, dishsoup, and alcohol???
why should we add these things?????
thats what i as saying…in the video she said nothing about salt!! but get the dish soap n alcohol part
salt and dish soap breaks open the cells to release all proteins, RNA, and DNA into the solution. The alcohol precipitates the DNA so you can pull it out of the solution.
i did this experiment in school, and it was super fun(:
Hi! I had a lot of fun with this experiment. I’m just getting started with DIYbio / biohacking and was hoping you could recommend more experiments like this. Maybe something a bit more advanced or that utilizes a different technique. Any help would be greatly appreciated. Thanks!
I really appreciate Tito
s work.Its true that a scientist is known by his inventions and discoveries (in short what the scientists proves through experiment)not that how much knowledge the scientist had.I appreciated titos work because it is so simple and easy.One thing I would like to ask from tito that how a person can verify after the experiment that the obtained stuff contains DNA?
Please answer my Question…
Thanks
Could you follow the same procedure if it was a human liver tissue being extracted?
Hey!!! Thanx soooooooooo much4 the experiment! im using it in a science fair at my skool some weeks from now.
But….are thait any experiments i can use to get the dna from a plant’s stem? please answer this question it would be very helpful and i would surely appreciate it.