DNA in a Blender
What To Do

You have an important safety responsibility if you are going to do this experiment.
Read our safety warning!
1 Chop up the onion into chunks and put it in the blender. Your adult lab assistant should do this. Chop up the onion into chunks and put it in the blender.
2 Add a teaspoon of salt and twice as much water as the onion mixture. Blend for about ten seconds. You should end up with a mushy mixture. Add a teaspoon of salt and twice as much water as the onion mixture.
3 Label two clear glasses with masking tape. Write "control" on one and "liquid soap and enzymes" on the other.
4 Strain the onion slush by pouring it through a sieve or strainer into a mixing bowl or pitcher. Strain the onion slush by pouring it through a sieve or strainer into a mixing bowl or pitcher.
5 Fill between one-third and one-half of each glass with the onion juice. Pour the same amount into each. Fill between one-third and one-half of each glass with the onion juice.
6 Add dishwashing liquid — one-sixth the amount of the onion juice — to the glass labeled "liquid soap and enzymes." (Don't add any to your control.) Add dishwashing liquid — one sixth the amount of the onion juice — to the glass labeled liquid soap and enzymes.
7 Add a half-teaspoon of meat tenderizer to the glass labeled "liquid soap and enzymes." (Don't add any to your control.) Add a half-teaspoon of meat tenderizer to the glass labeled liquid soap and enzymes.
8 Stir gently and wait ten minutes. Don't stir too hard or you'll break the long, fragile DNA molecules. Use a different spoon to stir each glass.
9 Slowly (you must do this slowly) pour alcohol into each glass. The amount of alcohol in each glass should equal the amount of mixture in the glass. Don't stir. Slowly pour alcohol into each glass.
10 You should see alcohol floating on top of your onion mixture. After a few minutes, stringy globs will appear in it. That's the DNA! You did it! You should see alcohol floating on top of your onion mixture.
11 Slowly swirl a stick through the alcohol. DNA clumps should stick to it. You can then lift them up for a closer look. Go ahead and touch the DNA—but wash the slimy stuff off your hands afterward!
Slowly swirl a stick through the alcohol. DNA clumps should stick to it.You can then lift them up for a closer look.
12 What happened in the control? Does it look the same or different?
More Experiements
You can do this experiment with other common foods. Try peas, kiwis, broccoli, spinach, chicken liver, and bananas. Then experiment with whatever you want and see what happens! Keep a journal of your experiments.
Try using warm water and chilled alcohol. Does this change your results?
Strain the onion mixture through a coffee filter instead of a sieve. Does the DNA make it through?
Experiment with different amounts of ingredients. Leave some out entirely and see what happens. This is similar to what you did in the control. Will the experiment work without using meat tenderizer? Find out by using three glasses: one with liquid soap only, one with liquid soap and meat tenderizer, and one with neither.
This experiment was adapted from procedures developed by the Genetics Science Learning Center at the University of Utah.
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