Thursday, January 01, 2009

Dude. Extracting DNA.

How cool is that?
We're going for a banana.
You know. Because it's the one on the list that we have sitting on our counter.

Wanna play, too?

You'll need the following things:
a food - kiwi, strawberry, banana, or onion
A filter - any coffee filter will work. Fold it cone-like.
a 10ml measuring tube (that you can close). Think baby medicine syringes. Behind your silverware tray. :)
a thermometer that shows 50* Celsius - which is 122* Fahrenheit
2 pipettes
a fork and a knife
a funnel or sandwich bag
a clean cup/glass
a measuring cup
laundry detergent (it shows powdered in the picture - we use liquid. So we're gonna use that. If our experiment fails, maybe this is why?)
a timer
2 bowls that are large enough to hold your measuring cup
denatured alcohol, rubbing alcohol, or ethanol - the alcohol must be ice-cold. You can store it in the freezer overnight beforehand.

The thermometer that came with our kit was Celsius only, and I am totally unfamiliar with that. I kept shaking the thermometer - It says 20*! They gave us a broken one! :) I had no idea if 50* was cold or hot, 'til I looked it up on a conversion page online. 122* Fahrenheit, then.
(I had a thought that maybe we'd use Trev's new calculator that Santa left in his stocking to figure the formula for converting celsius into fahrenheit, but they lost me at the multiply by 9/5... thought that might tax me him too much... especially on a calculator!
Do it if you're so inclined, I've moved on. :)

Cut and mash your strawberry, half of your banana or kiwi, or 1/4 of your onion.
note: don't throw the other half of the banana out, in case your little sister starts eating your science experiment.
Put it in your measuring cup.
Add 1/2 cup of warm water.
Add 5ml detergent.
Stir, stir, stir, stir.
Set your measuring cup mixture in the bowl with a water temperature of 50* Celsius, or 122* Fahrenheit.
Set your timer for 12 minutes.
When your 12 minutes are up, put the measuring cup in the ice bath (the bowl is half full of ice).
Set your timer for 5 minutes.
In that five minutes (stirring the fruit/detergent/water mixture occasionally), get your filter ready, and rinse out your 10ml measuring thing so it's clean (detergent free) again.
If you have a funnel - great! Put your cone filter in your funnel. If you don't (or cannot find it, and suspect that it might be out in the frozen sandbox) then cut a sandwich bag into a cone shape, and snip the corner to make a hole. (Er - things got a little scary/hectic for us in the next step for a minute - until we put a rubberband around the plastic bag to secure our "funnel" to our glass. That right quickly put a stop to the panic. We'd recommend it.)
When your five minutes is up, pour your fruit solution into the (secured) filter.
Wait for the solution to collect into the cup below.

Now comes the exciting part..... The filtered liquid in the cup below is called the supernatant.
(Su'per nay tent). The DNA is in the supernatant!
The material remaining in the filter is the cell walls, cell membranes, and cytoplasmic leftovers. But not the DNA. Most all of the DNA (DeoxyriboNucleic Acid) went through the filter and is now in the supernatant in the cup below.

When you have enough to make 5ml of supernatant in the bottom of your glass, extract it with a pipette, and squeeze 5ml into the measuring tube.
Um - at this point we thought something stable was a good idea, as we'd already had one mishap about half-way through...

Add a pinch of salt.Take your very cold alcohol out of the freezer, and squeezing the pipette along the sides of the tube, add enough alcohol to make 10ml total liquid.

Seal up your tube.

Rock it back and forth a few times.

See the white stuff that has appeared?That's the DNA!
Totally awesome.

Now put it on ice or in the freezer for at least 10 minutes or 'til tomorrow.

Meet DNA:
Cells are comprised of a cell wall, an outer membrane, cytoplasm, and a nucleus. DNA is inside the nucleus of almost every cell.

DNA is about 34,000 times thinner than a human hair, and 7,500 times thinner than a spider's thread of his web.

What happened:

The laundry detergent broke up the oily cell membranes (outer layer or "shell") from the fruit.

Cutting and stirring the fruit broke up the tissue and aided the detergent in reaching more of the fruit cells.

Adding the warm water caused the cells to swell and break up.

The warm bath increased the potency of the detergent (see above).

The heat also increased the activity of molecules -enzymes- within the fruit. Some of these enzymes ate the proteins that were bound to the DNA. By digesting them, the DNA was released into the detergent solution.

The icebath slowed down the the destructive chemical reactions that would eventually destroy the DNA.

The filter captured the cell walls, membrane material, and the chlorophyll (the green pigment in plants), and the DNA passed through with the supernatant.

Lastly, the chilled alcohol and the added salt caused the DNA to come out of solution (to precipitate). DNA is not soluble in alcohol.


We'll check it out.

A way to do that is to lift the globby white stuff (DNA) out of the tubewith something small (toothpick, stirrer, pipette), and put it on a tray.

How does it feel? Behave?
Much of the info that is in this DNA (A, T, G, and C!) is also in yours and mine.

You know we'll be checking this one out under the microscope tomorrow!!

Now let me say that this info has come to us via DNA, and is a fabulous find. I don't imagine that the info that we've provided will suit you to your satisfaction, so please consider buying this kit -- I'm so looking forward to checking out more of them!
...And this is just one of the eight projects!


  1. Yay. Thanks for the instructions and book link. We'll have to try too. It does look like a cool project.

    Of course my husband wants to know when you will begin sequencing it. ;)

  2. Wow... that is very cool! Thanks for the info, think we'll give it a try.


Thanks so much for sharing your thoughts!