How to Make Starch Gel for Electrophoresis
To analyze DNA through electrophoresis, you must first prepare the gel. As its name implies, the gel is made from a mixture of a starch called agarose, usually sold in powdered form. Never mix the gel with pure water -- you must always use buffer or else you'll have problems when you try to run the gel. The following procedure is intended for electrophoresis chambers of the size typically found in teaching labs; if your unit is larger or smaller, adjust the amounts of each chemical as appropriate.
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Things You'll Need
- Graduated cylinder
- Beaker
- 10X Tris-acetate EDTA buffer
- Deionized H2O
- Erlenmeyer flask
- Agarose powder
- Scale
- Kimwipe
- Microwave
- Pasteur pipet
Instructions
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1
Mix up 350 ml of 1X TAE buffer solution. Since the original stock is 10X, you should measure out 35 ml of the 10X stock then add 315 ml of deionized H2O (dH2O) and swirl gently to mix. You'll only need 50 ml to actually make the agarose gel; the remaining buffer will be used in the electrophoresis chamber itself.
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2
Pour 50 ml of your 1X buffer solution into the Erlenmeyer flask. Measure out 0.5 g of agarose and add it to the flask, then swirl to mix.
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3
Stuff a Kimwipe into the mouth of the flask and place it in the microwave oven. Heat it for 1 minute. DO NOT leave it unattended -- turn off the microwave once the solution in the flask begins to boil. If you overheat the solution, it will spatter the microwave and make a time-consuming mess.
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4
Using a Pasteur pipet, lay a thin line of gel along the place where the baffles in the electrophoresis chamber touch the gel bed. Place the comb over the gel bed so that the teeth face down towards the bed. Adjust the depth of the teeth using the comb screws until they are just above the bottom of the plate. They SHOULD NOT be touching the plate.
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5
Let the gel cool to about 60 degrees Celsius -- at which point the flask will still be hot to touch. Add dye (e.g., ethidium bromide or SYBR-safe) as directed by your protocol.
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6
Pour the agarose into the gel bed and allow it to cool until it solidifies.
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