7th Grade Science

2. Amazing Background Information (Read Only)
The nucleus of each of your cells contains multiple long
strands of DNA with all the instructions to make your entire
body. If you stretched out the DNA found in one of your
cells, it would be 2-3 meters long. To fit all that DNA inside a
tiny cell nucleus, the DNA is wrapped tightly around proteins.
To extract DNA from your cells, you will need to separate the
DNA from these proteins and other types of biological
molecules that are contained in your cells. You will be using
the same basic steps that professional scientists use when
they extract DNA in their labs. Some of these include
breaking apart the cell structure, separating the contents,
and isolation the DNA from the remaining parts.

3. Take Notice:

4. Purpose (copy this down in your notebook):
1. To learn how to isolate your own genomic DNA from
your cheek cells through the DNA extraction method.
2. To review the concepts of DNA structure and better
understand how it is organized in the cells of living
things.

5. Your Materials (list these in your notebook)
Test tube
Necklace string
Pendent Tube
Plastic Pipet
Plastic cup

6. Procedure (Read Only)
1. Getting Your Sample of Cells
a. Label your 15 mL tube with your name.
b. Obtain a plastic cup with a small amount (2 mL) of
Gatorade.
c. Vigorously swish the Gatorade around in your mouth for
1-2 minutes. DO NOT SWALLOW.
d. Gently and continuously scrape the inside of your cheeks
with your teeth to help release cheek cells.
e. Afterwards, spit the drink (with collected cheek cells)
back into the plastic cup and then gently pour the
contents of the plastic cup into your labeled 15-ml tube,
put cap on, and let sit undisturbed for 5 minutes.
f. Discard the cup in the proper place.

7. Check-in #1 (respond in your Notebook)
1. Why are you not going to swallow the Gatorade?
2. How long do you need to swish the Gatorade around
in your mouth before spitting it back into the cup?

8. Procedure (Read Only)
2. Adding Detergent
a. Bring your tube up to Mr. Binder and he will add a small
amount (2 ml) of detergent to a test tube.
b. Put the cap on your tube and invert (turn upside down and
back) five times. Place the tube in the rack to let stand for 2
minutes without moving it.

9. Check-in #2 (respond in your Notebook)
Check-in #2 (respond in your Notebook):
1. Why is detergent being added to the solution
containing your cheek cells?
2. How many times must you invert the tube once your
cap is on tight?
3. How long must you let the test tube sit without
moving it?

10. Procedure (simply read)
3. Adding Alcohol
a. Have Mr. Binder add enough 70% ethanol to fill the tube
to the 12-13 mL marking. Do not shake or otherwise mix
your tube. You will now see two distinct layers in your
tube.
b. Carefully observe your tube and watch for wispy
translucent strands of DNA start to rise up from the
bottom layer into the top layer. The DNA will resemble a
cobweb. Tiny bubbles will appear as evident of a
reaction.
c. Place your test tube in the rack and let it sit undisturbed
for 10 minutes. During this time DNA will continue to
come out of solution.

11. Check-in #3 (respond in your Notebook)
Check-in #3 (respond in your Notebook):
1. How many layers will you see in your 15mL tube at
this time?
2. What will the DNA resemble and how will you know
there was a reaction in the tube?
3. How long do you need to let the test tube sit before
moving to the next step? Why do you think this is?

12. Procedure (simply read)
4. Transferring Your DNA (Isolation)
a. While you let your test tube sit (for at least 10 minutes),
tie the ends of your thread together with a knot to form a
loop. Make sure the loop fits over your head.
b. When the 10 minutes is up, use your plastic pipet to
transfer the DNA from your 15 mL test tube into your
pendent tube. Be careful to squeeze the air out of the
pipet before you put the pipette in the test tube; then
gently suck up your DNA
c. Carefully draw-up the DNA from your sample with your
pipet and, before squeezing it into your pendant tube,
allow it to settle to the bottom of the pipet. You do not
need to transfer all the DNA. DO NOT overfill the
pendant tube.
d. Close the cap of the pendant tube. Now you have a
necklace with your very own DNA!

13. Check-in #4 (respond in your Notebook)
Check-in #4 (respond in your Notebook):
1. Why do you need to make sure your loop can fit over
your head?
2. What are you using to actually isolate your DNA from
the other materials in the tube?
3. Why might you not want to transfer all of the DNA
from the 15mL tube to the pendant tube?

14. Viola! Your DNA Necklace!