Looking at DNA - A kitchen experiment
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Extracting DNA At Home The Tech Museum of Innovation San Jose, CA
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See the accompanying videos:http://www.youtube.com/watch?v=4ij8pYNFnEMhttp://www.youtube.com/watch?v=HgUgAeAb4Ng
Transcript of Looking at DNA - A kitchen experiment
Extracting DNA At Home
The Tech Museum of InnovationSan Jose, CA
What does DNA look like?
DNA is a double helix
What is DNA?
Genes are like recipes
Every living thing has DNA
Every living thing has DNA
Every living thing has DNA
An animal cell
An animal cellCell membrane
An animal cell
Mitochondria
Cell membrane
An animal cell
Mitochondria
Cell membraneNucleus
DNA is kept inside the nucleus
Nucleus
To get the DNA out…
To get the DNA out…
Let’s get started!
Stuff you need
• Something with DNA
Stuff you need
• Strawberries
Stuff you need
• Strawberries• Sandwich baggie
Stuff you need
• Strawberries• Sandwich baggie• Water
Stuff you need
• Strawberries• Sandwich baggie• Water• Clear glass (or test tube)
Stuff you need
• Strawberries• Sandwich baggie• Water• Clear glass (or test tube)• 1/4 teaspoon measuring spoon
(optional)
Stuff you need
• Strawberries• Sandwich baggie• Water• Clear glass (or test tube)• 1/4 tsp measuring spoon (optional)• Dishwashing soap
Stuff you need
• Strawberries• Sandwich baggie• Water• Clear glass (or test tube)• 1/4 tsp measuring spoon (optional)• Dishwashing soap• Rubbing alcohol
Step 1
Put the rubbing alcohol in the freezer
Plant cells are like animal cells
Animal CellAnimal Cell (like our cells)(like our cells)
PPlant lant CCellell(like a strawberry cell)(like a strawberry cell)
cell membrane
Nucleus (with DNA!)
cell wallcell wall
mitochondria
Remember, to get the DNA out…
Step 2Put 2 or 3 (or 4) strawberries in
the sandwich baggie
Step 3Add a little bit of water
(to make it easier to pour out later)
Step 4
Seal the baggie
Step 5
Smush the strawberries!
Break down those cell walls!
Step 5Smush for about 2 minutes or so…
Until there are no big chunks left and thewater is very red
Step 6
Pour the strawberry cell goointo the glass
To avoid the chunks…
• Coffee filter• Cheesecloth• Or just pour carefully!
What’s in the glass?
See anything that looks likeDNA yet?
What’s in the glass?
Strawberry guts - yum!
What we just did
The DNA is stillinside the nucleus
Nucleus
Let’s break downthe nucleus wall!
Nucleus
How can we break thenucleus wall?
The nucleus wall ismade of lipids (fat!)
Lipids = fatLipids = fat
Soap breaks apart grease & fat
Soap breaks apart grease & fat
And nuclear membranes!
Step 7
Add dishwashing soapto the strawberry cell gut soup
See anything that looks likeDNA now?
Why can’t we see the DNA yet?
Why can’t we see the DNA yet?
DNA can dissolve inthe strawberry gut soup
Why can’t we see the DNA yet?
DNA can dissolve inthe strawberry gut soup
Like sugardissolves in water
Sugar
But DNA does NOTdissolve in alcohol!
DNA does NOTdissolve in alcohol
When we add the alcohol, the DNA willclump up so we can see it!
Step 8
Slowly add the cold rubbing alcohol tothe soapy strawberry goo
Make two separate layers
Like oil on water
What do you see?
Do you see some cobwebbywhite stuff?
That’s the strawberries’ DNA!
That has all the instructions formaking an entire strawberry plant!
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 nextthings….
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.)
