What Does The Strawberry DNA Look Like?

Strawberry DNA Extraction is an easy experiment with household materials. It can be conducted at home or at school for all ages. DNA can be found in organic creatures. We use strawberry for it yields more DNA and it is easier to extract.

Age：8+          Est. Time: < 30 mins

 Safety 

1. Do not eat the strawberry used in this experiment.
2. Be careful with the fragile glassware.

 Materials list 

• Strawberries
• 10g dishwashing soap 10g
• 5g salt
• 50ml 99.5% Alcohol
• Water
• Ziplock bag
• Beakers
• Glass rod
• Cylinder
• Electronic balance
• Funnel
• Gauze
• Toothpick

 Instruction 

Step 1/6 – Add 2.5g of salt and 10g of washing soap in 50ml water, stir it with a glass rod gently to avoid creating too many bubbles.

Step 2/6 – Freeze 50ml alcohol for half an hour.

Step 3/6 – Cut the strawberries into small pieces and put them in a ziplock bag, seal the bag and squeeze the strawberries.

Step 4/6 – Pour the extraction liquid to a ziplock bag, remove as much air from the bag as possible, seal it closed and smash it until there are no big pieces left.

Step 5/6 – Filter the mixture liquid through the gauze two times.

Step 6/6 – Slowly add the alcohol into the liquid mixture and you can see something like the cloud is generated, that is DNA. Stir it slowly with a toothpick and it will wind around the toothpick.

 Troubleshooting 

Why does the mixture liquid not go down when filtering?
– There are solid blocks blocking the small holes on the gauze. The strawberries should be crushed as much as possible before filter it.

 Scientific description 

The reason why we use strawberries in this experiment is that not only there are more DNA in the strawberry than other fruits but also the strawberry is easier to crush. Plant cells are composed of cell walls, cell membranes, cytoplasm, and nucleus. DNA bounded with protein is found within the cell wall, so extracting DNA requires releasing it from the cell and separating it from other substances like protein. The procedure is as follows:

First, the washing soap dissolves the cell membrane and release the DNA from the cell.

Secondly, salt separates the protein from the DNA strand and shields it from the charge, which makes it easier for DNA to get together.

Finally, DNA can dissolve in water but Ethanol (especially the freezing ethanol) so the DNA will come out when ethanol being poured into.

 Extension 

Search on the internet which fruits possess more DNA. Try to separate their DNA out and see if it is the same as strawberries.

 Disposal 

Pour the liquid into the sink and the solid can be treated as domestic waste. And, do not forget to wash what is used.