�鶹Լ��

Aim

In this practical you will extract the DNA from strawberries. Strawberries can have up to eight copies of each chromosome and so contain a lot of DNA. When extracted from the strawberry this volume of DNA means it is visible to the naked eye as white threads.

Method

1. Put the strawberry into the plastic bag, seal it and crush for about 2 minutes.
2. In a beaker mix together 10 cm³ of washing up liquid, 1 g of salt and 100 cm³ water. This mixture will break down cell membranes and release the DNA.
3. Add 10 cm³ of the extraction liquid to the bag with the strawberry mix together for 1 minute.
4. Filter the strawberry mixture.
5. Pour 10 cm³ of ice-cold 90% ethanol down the side of the beaker into the strawberry mixture, do not mix or stir. The DNA will separate out into this layer.

Within a few seconds you should see a white cloudy substance form in the clear layer above the strawberry mixture. Use a lolly stick to pull strands of this out of the top layer. This is the strawberry DNA.