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DNA extraction - strawberries

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.

Materials

• 1 x Strawberry
• 10ml Washing up liquid
• 1g Salt
• 100ml water
• 10ml ethanol (cold)
• 1 x filter paper
• 1 x sealable plastic bag
• Cocktail stick or lolly stick

Method

1. Put the strawberry into the plastic bag, seal it and crush for about 2 minutes.

2. Mix together 10ml of washing up liquid, 1g of salt and 100ml water in a beaker. This micture will break down cell membranes and release the DNA.

3. Add 10ml of the extaction liquid to the bag with the strawberry. Mix together for 1 minute.

4. FIlter the strawberry mixture

5. Pour 10ml of ice-cold ethanol down teh 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 start to see a white cloudy substance form in the clear layer above the strawberry mixture. Use a lolly stick to pull strands of this our of the top layer.

This is the strawberry DNA.