Kid Science: Extracting DNA from Plants

Oklahoma State conducted a survey a couple of years ago that for me really hits home the need for exposing people to science as much as we can.  The survey asked "Do you support mandatory labels on food produced with genetic engineering?"  As expected 82% of people polled agree with that statement.  However another very important question was on the survey that asked  "Do you support mandatory labels on food containing DNA?"   For that that question 80% of participants supported this idea..

Let's think about this one for a minute.  DNA is the building block of life.  Everything living contains DNA including our food which means every food product we eat contains DNA.  The worrisome part is if our society has this misconception on DNA, then of course they are going to have misconceptions on GMOs.  People might support labeling GMOs but it is hard to know if they really understand why they are asking for labels if labeling all food with DNA get the same response.

Well there is a a quick and fun way to show that even our food contains DNA.  We just had National Bring your Kids to Work Day.  A shout out goes to all the awesome people I work with at Bayer CropScience for organizing a great day that not only let us take our kids to work, but introduced them to the fun side of science.   My two boys Landon and Carter got spend a day learning and doing science.  Landon wanted to do one of the experiments we learned again   So we both are on a mission to prove that even plants have DNA.  In this experiment we are going to actually extract the DNA and there will be so much of it we will actually see it .

The items we need are:

Fruit:  Strawberries or Bananas work best
Detergent (Dish Soap)
Salt
Zip-lock bag
Coffee Filter (an funnel if you have one)
Toothpick, paperclip, or wooden stick
COLD Alcohol:  95% ethanol works best   but 70% rubbing alcohol will work too.

The first step is to make sure your alcohol is cold.  This is important to protect the DNA.  Go ahead and put your alcohol in the freezer and get it very cold (it will not freeze).

The experiment:

1.  Put piece of banana or strawberry in a Ziploc bag
2.  Push air out, close bag and and mash for 2 minutes
3.  Add 10 mLs of salty water (just add 3-4 good pinches) + 2-3 drops of dish soap in the bag.  Mash for 2 more minutes
4. Take a coffee filter, place in funnel on top of a tube or container.  Pour fruit paste in filter and let the liquid pass through.  You may have to squeeze the filter.  Bananas are a little pasty and need more help getting the liquid through than strawberries.
5.  Pour 2 ml of the filtered contents into a clean tube.
6.  Add 5 mL of COLD ethanol by running it gently down the side of the tube (2.5 volume ethanol to 1 volume fruit juice).  Do no stir or shake..
7.  Wind the DNA with a stick.  Even before you wind it you will see the DNA suspended in your fruit juice.

Here are the supplies you need:

Put the banana in the bag

Mash the fruit:

Add Salty water and dish soap and mix again.  The soap breaks the cells apart so the DNA will be released out of the cells.  The salt keeps the other stuff in the cells from separating with the DNA.

Pour the fruit paste into a coffee filter and filter the juice into a tube:

Squeeze the paste to get the pure fruit juice:

Get 2 mL of the juice in a new tube.:

Add 5 mL of ethanol down the side.  Do not shake or stir.  DNA is not soluble in alcohol.  So once you add it the DNA is not in a dissolved state like it was was in the fruit juice.  Once it becomes insoluble you can see it with the naked eye.

The DNA is already precipitated out:

Place a wooden stick in the tube and twirl.  The DNA will stick right to stick.  Bananas work so good!!

Yep... It looks like a big snot ball.

Strawberry works too and you get the added benefit of the red color.

Even the baby wanted to do some science. While we were doing this experiment I turned around to find her like this:

Science is fun!  And what an easy and great learning tool.