Looking at DNA - A kitchen experiment

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See the accompanying videos:
http://www.youtube.com/watch?v=4ij8pYNFnEM
http://www.youtube.com/watch?v=HgUgAeAb4Ng

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  • i want to ask why we must use cold alcohol and why DNA clump up when alcohol is added?
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Looking at DNA - A kitchen experiment

  1. 1. Extracting DNA At Home The Tech Museum of Innovation San Jose, CA
  2. 2. What does DNA look like?
  3. 3. DNA is a double helix
  4. 4. What is DNA?
  5. 5. Genes are like recipes
  6. 6. Every living thing has DNA
  7. 7. Every living thing has DNA
  8. 8. Every living thing has DNA
  9. 9. An animal cell
  10. 10. An animal cell Cell membrane
  11. 11. An animal cell Cell membrane Mitochondria
  12. 12. An animal cell Nucleus Cell membrane Mitochondria
  13. 13. DNA is kept inside the nucleus Nucleus
  14. 14. To get the DNA out…
  15. 15. To get the DNA out…
  16. 16. Let’s get started!
  17. 17. Stuff you need • Something with DNA
  18. 18. Stuff you need • Strawberries
  19. 19. Stuff you need • Strawberries • Sandwich baggie
  20. 20. Stuff you need • Strawberries • Sandwich baggie • Water
  21. 21. Stuff you need • Strawberries • Sandwich baggie • Water • Clear glass (or test tube)
  22. 22. Stuff you need • Strawberries • Sandwich baggie • Water • Clear glass (or test tube) • 1/4 teaspoon measuring spoon (optional)
  23. 23. Stuff you need • Strawberries • Sandwich baggie • Water • Clear glass (or test tube) • 1/4 tsp measuring spoon (optional) • Dishwashing soap
  24. 24. Stuff you need • Strawberries • Sandwich baggie • Water • Clear glass (or test tube) • 1/4 tsp measuring spoon (optional) • Dishwashing soap • Rubbing alcohol
  25. 25. Step 1 Put the rubbing alcohol in the freezer
  26. 26. Plant cells are like animal cells cell wall Animal Cell Nucleus (like our cells) (with DNA!) cell membrane Plant Cell (like a strawberry cell) mitochondria
  27. 27. Remember, to get the DNA out…
  28. 28. Step 2 Put 2 or 3 (or 4) strawberries in the sandwich baggie
  29. 29. Step 3 Add a little bit of water (to make it easier to pour out later)
  30. 30. Step 4 Seal the baggie
  31. 31. Step 5 Smush the strawberries!
  32. 32. Break down those cell walls!
  33. 33. Step 5 Smush for about 2 minutes or so… Until there are no big chunks left and the water is very red
  34. 34. Step 6 Pour the strawberry cell goo into the glass
  35. 35. To avoid the chunks… • Coffee filter • Cheesecloth • Or just pour carefully!
  36. 36. What’s in the glass?
  37. 37. See anything that looks like DNA yet?
  38. 38. What’s in the glass? Strawberry guts - yum!
  39. 39. What we just did
  40. 40. The DNA is still inside the nucleus Nucleus
  41. 41. Let’s break down the nucleus wall! Nucleus
  42. 42. How can we break the nucleus wall?
  43. 43. The nucleus wall is made of lipids (fat!) Lipids = fat
  44. 44. Soap breaks apart grease & fat
  45. 45. Soap breaks apart grease & fat And nuclear membranes!
  46. 46. Step 7 Add dishwashing soap to the strawberry cell gut soup
  47. 47. See anything that looks like DNA now?
  48. 48. Why can’t we see the DNA yet?
  49. 49. Why can’t we see the DNA yet? DNA can dissolve in the strawberry gut soup
  50. 50. Why can’t we see the DNA yet? DNA can dissolve in Su gar the strawberry gut soup Like sugar dissolves in water
  51. 51. But DNA does NOT dissolve in alcohol!
  52. 52. DNA does NOT dissolve in alcohol When we add the alcohol, the DNA will clump up so we can see it!
  53. 53. Step 8 Slowly add the cold rubbing alcohol to the soapy strawberry goo
  54. 54. Make two separate layers Like oil on water
  55. 55. What do you see?
  56. 56. Do you see some cobwebby white stuff?
  57. 57. That’s the strawberries’ DNA!
  58. 58. That has all the instructions for making an entire strawberry plant!
  59. 59. If you don’t see a lot of DNA… • Keep watching! • Or put your experiment in the fridge and come back to look later • Or do some experiments to see if you can get more by trying out these next things….
  60. 60. Things to experiment with… • Amount of soap • Different types of soap (brand, hand soap, shampoo, laundry detergent, etc.) • Number/size of strawberries • Other sources of DNA (bananas, kiwis, sweetbreads, peas, etc.)

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