DNA EXTRACTION FROM
Name
Per.
CHEEK CELLS
Today’s Date
Due Date
The purpose of this lab is to extract your DNA from your cheek cells and save it
in a small tube to make your own and unique DNA necklace.
Materials:
Each Student Needs:
 1 test tube (25 x 150 mm)
 1 cup with 2 ml of sports drink
 1 length of thread
 1 microtubule with cap
 1 plastic bulb pipette with ml
markings
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Each Group Needs:
test tube rack
beaker of 10% dish soap – lysis solution
masking tape
2 permanent markers
2 large beakers of water: one for 1st
wash, and another for rinsing.
Solution Station:
 syringe
 multiple 10 ml graduated cylinders
 ice-cold ethanol in ice bucket
Procedure:
1.
Labeling test tube:
Using marker and tape, label one test tube with your initials. Put tape near top
of test tube.
2.
Collecting cheek cells:
Collect cheek cells by swishing sports drink in mouth for 2 whole minutes,
rubbing cheeks against teeth to remove cells. DO NOT SWALLOW (you’ll be
tempted to).
3.
Spit sports drink remains and cells back into cup.
4.
Pour cell mixture from cup into test tube. Put cup aside to use later.
5.
Split cells open (call ‘lysing’) with the lysis agent:
Use the pipette to add 2 ml of lysis solution. Put 1 ml of lysis in at a time
(because pipettes only have marking for 1 ml). Drop slowly and don’t let pipette
touch the saliva.
6.
Wash pipette:
Wash out pipette completely in wash water beaker, and rinse completely in rinse
beaker.
7.
Inverting tube:
Close off test tube by placing thumb (if thumb big enough – use palm of hand if
not) on top of test tube and invert the tube GENTLY AND VERY SLOWLY 5
times so that bubbles do not form.
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Set tube in test tube rack for 2 minutes.
Precipitating DNA:
After 2 minutes, take test tube to ethanol station and receive 8 ml of ice-cold
ethanol in a graduated cylinder.
Hold test tube on a slant and VERY CAREFULLY pour the ethanol down the side
of the test tube so that it remains as a layer on the top of the cell/lysis agent
mixture. DO NOT MIX THE LAYERS.
Return the test tube to the rack and leave for 15 minutes.
Observe the white precipitate (solid), which will be wispy threads of DNA, form
between the lysis agent and ethanol.
Making DNA necklace:
While waiting for the precipitate to form, tie the thread to the lid of the
microtubule and knot the ends to make a necklace that fits over your head.
After 15 minutes has passed, use cleaned pipette to carefully remove the DNA
from the ethanol layer. DO NOT PUT PIPETTE into the cell/lysis agent mixture.
Make sure the DNA is at the tip of the pipette when you place it in the
microtubule. If necessary, release a few drops of the ethanol into the empty
cup so that DNA will be at tip before placing in microtubule.
Close lid and wear your DNA with pride!
Clean up! Wash and rinse pipettes very well. Pour test tube contents into the
sink and use a test tube brush to thoroughly clean the test tube.
While you wait for the DNA to precipitate, write an acrostic poem with the letters
DNA. Use two or three sentences per letter.
D
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