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Friday, February 10, 2012

DNA extraction from onion cells

DNA, or deoxyribonucleic acid, is the hereditary material in almost living "things".
Nearly every cell in a person’s body has the same DNA. Most of DNA is located in cell nucleus. We can say this DNA is like a stepladder and it can be as long as 1,80m but it can fold itself so tight it can be stored in a small space with micro dimensions.

Lets see how we can see this DNA without any microscopy help.

We need:
  • 2 bowls, one of them must be transparent,
  • a knife,
  • a onion,
  • dish detergent,
  • salt,
  • water,
  • 2 spoons,
  • alcohol.
How to:
  1. Peel the onion;
  2. Cut the onion, into small pieces, to the bowl;
  3. Add some dish detergent, enough to cover it;
  4. Add the salt (1/2 tablespoon);
  5. Finally add the water (2 tablespoons);
  6. Mix, careful, we don't want it to form bubbles;
  7. Wait 20 min;
  8. Mix again;
  9. Separate the liquid layer from the rest, the DNA is on the liquid, reject the rest.
  10. Add alcohol to the liquid, slowly, we want the alcohol to form a second layer above the liquid, try to make the alcohol run down the bowl wall.
  11. Don't mix the layers;
  12. Wait another 20 min.
What happens?
You can see small white strands; some of them may look like small clusters.

DNA precipitates when mixed with alcohol; this means it's not soluble in this reagent. This causes the DNA to clump together when there is a lot of it. And, usually, cells contain a lot of it!

Salt- Helps DNA to precipitate
Cold water- Helps to maintain DNA intact. If we use hot water cellular enzymes can destroy the DNA strand.

Et voilá!
Genetic in your kitchen!


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