Gel electrophoresis: Making the gel

Tasha is a Year 13 student who learnt how to make a gel at Genesis R&D in Auckland. The gel can be made using a gelling agent like agarose. The agarose is mixed with buffer and heated so that it dissolves. Ethidium bromide may be added. This is a chemical that binds to DNA and fluoresces (shines up) under UV light so that the position of the DNA in the gel can be visualised. Once the ethidium bromide is added, the agarose solution is poured into a mould and allowed to set. 'Combs' are placed into the gel to create moulded wells where the DNA / protein solution can be added.

Transcript

Narrator

Gel electrophoresis is a technique that is used to separate DNA pieces according to size. First a gel must be made. It’s a lot like making jelly. The agarose powder is weighed by Tasha. She then mixes the agarose with a buffer solution. Tasha then uses a microwave to heat the agarose solution. When the agarose has dissolved, the solution is cooled before pouring. Clare adds ethidium bromide to the gel. This is a chemical that binds to DNA, so that you can see it when the gel is put under UV light. Notice that Clare and Tasha are both wearing gloves. This is because ethidium bromide is poisonous. Tasha now pours the cooled agarose solution into a special electrophoresis tray to set. The white pieces are like two combs. They create a mould of holes in the gel where your DNA sample can be added.