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Name: _____________________________
Grade: __________ Date: ______________
Due Date: Thurs, Nov, 12, 2015
Science Experiment: Seeing Your DNA
Mary Bagley, LiveScience Contributor | June 06, 2013 04:59pm ET
When people think of DNA they usually visualize the elegant “twisted ladder”
shape seen in everything from advertising logos to Biology textbooks. This visual
is actually a kind of artist’s conception. It is a kind of scientific model, useful in
helping us understand how DNA functions, but in reality impossible to see.
The structure of a molecule is far too small to be seen with even the most powerful
of microscopes. Rosalind Franklin used the process of X-ray crystallography to
make an image of the DNA molecule that was used by Watson and Crick to build
that first model; but X-ray crystallography is a bit complex for most students to do
at home.
Still, some of you might want to do something a bit more dramatic than building a
DNA model out of toothpicks and gumdrops. You might not be able to actually see
little A,C,T and G pieces, or even a single DNA strand, but did you know that you
can use some common kitchen ingredients to extract DNA from your own cells —
DNA that you CAN see? First, read this related article: DNA: Definition, Structure & Discovery.
What You Need:
 Small
paper cups (You want the smallest sized cups.)
small cups
 1 bottle of colorless sports drink (You can also use a strong salt water
solution, but “Lemon Ice” flavored Gatorade tastes better — and you can
use the leftovers for refreshments after the lab!)
 Liquid dish soap (You want to use the lightest color or colorless brand you
can find)
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Al-Madinah School Science LAB
Nov 9th 2015
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A
few drops of pineapple juice (You could also try using a quarterteaspoon of meat tenderizer dissolved in a half-cup of water)
 1 wood skewer (You want the kind that looks like a very long toothpick.
Look in the baking aisle at the grocery store — many people use them to
test cakes for doneness.)
 Alcohol (You can use regular rubbing alcohol, but if you can find 91-percent
isopropyl alcohol at the drugstore get that. The closer to 100-percent
alcohol you use, the better this will work.)
 Narrow container with a lid (You can use a test tube with a stopper if you
have one. You could also use a small jar like you buy spices in. Make sure
it is clean and dry.)
What to Do:
1. 24 hours before you start, put the alcohol in the kitchen freezer. Don’t
worry, it won’t freeze, but it should be ice cold before you do your
experiment.
2. When you are ready, take a good mouthful of sports drink and
vigorously swish it around in your mouth like mouth wash. Keep going
for at least 2 minutes. This takes some stamina — it’s harder than it
sounds, to swish for that long! It also helps if you scrape the insides of
your cheeks a little with your teeth. No blood, please; we are after the
DNA from your cheek cells, not your blood type!
Get a sports drink that is light color or colorless.
3. Spit the sports drink and cheek cell solution into a small paper cup, then
pour it into your test tube or spice jar until it is about one-third full.
4. Add liquid dish soap until your container is about half full. Put the lid on
and mix the contents by rocking the container and turning it upside down
several times. Be gentle, your goal is to mix the contents but to avoid
causing bubbles from the soap.
5. Add a few drops of pineapple juice or meat tenderizer solution. Repeat the
gentle mixing.
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Al-Madinah School Science LAB
Nov 9th 2015
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6. Now it’s time to get that icy cold alcohol out of the freezer. Take the lid
off of your cheek cell solution and tilt the container in one hand. Use
your other hand to very gently trickle a small amount of alcohol down
the inside of the jar so that the alcohol forms a layer floating on top of
the cell solution. Return the container to its upright position and set it
aside for 1 minute.
Gently add alcohol to the solution.
7. After a minute, look carefully at the place where the alcohol makes a layer
floating on top of the cheek cell solution. You should see a band of white
gooey material suspended between the liquid layers. Gently put the skewer
down into the container so that the tip touches this material. Carefully
twirl the skewer in one direction only; if you are lucky the stuff will wind
around the skewer so that
you can lift it out through the alcohol layer to look more closely.
8. Behold your own DNA!
Why you did what you did:
1. Why did I have to swish so long?
First you had to collect enough cells to work. You are also using the salts in the
sports drink to begin to break the cell membrane and the membrane around the
nucleus to free the DNA.
Carefully twirl the skewer to extract the strand of DNA.
2. Why did I use the soap?
Cell membranes are made up of two layers consisting of fats, sugars and salts. The
fats are on the inside of the membrane where they can avoid touching the water
that surrounds the cell. Detergent molecules have two ends. One end of a detergent
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Al-Madinah School Science LAB
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molecule is attracted to fat and the other end is attracted to water. When you wash
your dinner plate; the fat-loving end of the dish detergent molecule attaches to the
grease from your hamburger and the water-loving end attaches to the water in the
sink. In the cheek solution, you were using the detergent to move the broken up
cell membranes away from the DNA.
3. Why did I use pineapple juice?
Pineapple juice and meat tenderizer both contain enzymes that further help to
break down the cell membrane.
4. Why did I use ice cold alcohol?
The DNA was dissolved in the water contained in the sports drink. DNA does not
dissolve in alcohol. When the cold alcohol was layered on top of the cheek cell
solution the DNA precipitated out of solution.
5. Why did I twirl the skewer?
Remember that famous DNA model. The DNA molecule is a very long strand with
a gentle twist. Your visible DNA material is actually many thousands of these
strands clumped together. Gently twirling the skewer allowed many of these
strands to wind around your skewer like thread around a spool.
6. What else can I try?
Try extracting DNA from fruits like bananas or strawberries. Try leafy vegetables
like spinach or kale. Take DNA from seeds like raw nuts or peas. Use about 2 cups
of plant material and about half a cup of water and a tablespoon of salt instead of
Gatorade. You will probably need to mix it in a blender as swishing that much in
your mouth would be kind of hard!
Rosie Begum
Al-Madinah School Science LAB
Nov 9th 2015
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Name: _____________________________
Due Date: Thurs, Nov, 12, 2015
Grade: ____________
Questions to explore:
1.
Do you get more DNA from using your cheeks, the fruit, the leaves or the
seeds? Why do you think this is so?
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2.
What do you have in common with a banana?
3.
What happens if the alcohol isn’t cold?
4.
Are there any steps you can leave out of the procedure and still get results?
5.
What other sources of DNA could you use? (Please avoid taking samples
from the family pet or from your little brother!)
6.
Could a CSI team use this technique to collect DNA for legal purposes?
7.
What techniques are used for forensic science or medicine?
Bibliography MLA vs. APA (note: use www.easybib.com for
MLA/www.bibme.org for APA)
1.
Bagley, Mary. "Science Experiment for Kids: Seeing Your DNA." LiveScience. TechMedia
Network, 06 June 2013. Web. 07 Nov. 2015
http://www.livescience.com/37252-dna-science-experiment.html
 This MLA format is displaying the URL (URL is mandatory for MLA
format)
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2.
Bagley, M. (2013, June 6). Science Experiment for Kids: Seeing Your DNA. Retrieved
November 7, 2015, from http://www.livescience.com/37252-dna-scienceexperiment.html
 This APA format is displaying URL
3.
Bagley, M. (2013, June 6). Science Experiment for Kids: Seeing Your DNA. Retrieved
November 7, 2015.
 This APA format isn’t displaying URL
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