Human Cheek Cell DNA Extraction Lab
Introduction
The genetic material in a living organism is found in the nucleus of each cell. Genetic material is in the form of DNA (deoxyribonucleic acid). DNA is made of long strands of nucleotides, organized into “chunks” called chromosomes. Humans have 46 chromosomes in each of their cells (23 from their mom and 23 from their dad). A small section of DNA that codes for a protein (or a trait) is called a gene. Genes are what determine your hair color, eye color, ear lobe shape, etc. They also tell your body how to run.
Procedure:
Release (but protect) the DNA!
1. Take a VERY small sip of sports drink
2. Swish the drink all around your mouth while carefully chewing on the insides of your cheeks
3. Spit drink into a paper cup
4. Pour liquid from cup into a test tube (up to 2/3 full)
Break open your cheek cells and their nuclei!
5. Add a few drops of detergent (shampoo or dishwashing detergent) into tube
6. Secure the cap on your tube and carefully invert your tube until detergent is mixed in.
7. Let stand 5 min (without mixing!)
Break up the proteins your DNA is wrapped around!
8. Add one “pinch” of meat tenderizer to your tube.
9. Let mixture sit at least 10 minutes.
Precipitate our your DNA!
10. Using a pipette slowly add about 2 pipettes full of ice-cold ethanol alcohol down the side of the tube. Do not mix.
11. Wait approximately 10 minutes for the DNA to precipitate. You will see cloudy white clumps at the level where the soap water meets the alcohol.
Clean Up
12. Throw away your cups. Thoroughly rinse the test tubes and pipettes using the sinks by the window. Place your rinsed out test tubes in the bin so they can be sanitized. Make sure that your lab table is completely clean.
Background Information
Why am I using sport drinks?
The salt in your sports drink helps enzymes that normally break up DNA to not work…keeping your DNA unbroken so you can see it better!
Why am I using detergent?
Detergent breaks open cell and nuclear membranes. This let’s the DNA out of the nucleus so you can see it!
Why am I using meat tenderizer?
Meat tenderizer “cuts” proteins away from your DNA so we can isolate it.
Why am I using alcohol?
DNA dissolves in water (like sugar or salt do)…making them invisible in water. But DNA does not dissolve in alcohol. It precipitates out. Precipitate means to become a solid from a solution.
Why is DNA that spiral shape?
DNA is made of 4 types of nucleotides (Guanine, Cytosine, Adenine, Thymine). These nucleotides contain sugar (deoxyribose), and a phosphate group (part of how DNA gets its name!). Guanine and Cytosine always pair up, and Adenine and Thymine always pair up. When they do this, because of their shape, they automatically become spiraled.
Conclusion:
Send your answer to the following questions in a Google Doc.
Write a paragraph explaining what happened in your experiment (what did you do and what were the results…be detailed!) and why it happened (what made the DNA come out of solution so you could see it?).