Biology, Answering the Big Questions of Life/DNA

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DNA condensation

Isolating DNA from Strawberries[edit | edit source]

Contrary to popular belief, DNA is not difficult to isolate.

This laboratory allows the students to isolate DNA from Strawberries in order to visualize DNA.

Why strawberries?

Strawberries are octoploid therefore they have a large amount of DNA.

Plus, I think that they smell nicer than onions.

Before the lab[edit | edit source]

  • Put the 95% ethanol in the freezer.
  • Make the extraction buffer.

Extraction Buffer[edit | edit source]

250 ml Water
30 ml Dish detergent
1 g Salt(sodium Chloride)
0.1g Meat tenderizer

Explanation of Procedure[edit | edit source]

1. The strawberries are mashed by hand in plastic bags. We are physically breaking down the cell walls to make it easier to access the cell contents.

2. Soap is added to break down the cell and nuclear membranes.

3. The meat tenderizer contains proteases which break down nucleases in the cell which would degrade the DNA otherwise.

4. The ethanol precipitates the DNA so that it can be visualized. The colder the ethanol, the less it will dissolve in the water.

5. DNA is very long and therefore it can be spooled around a stick.

For an alternative procedure using sweet peas, see the University of Utah's How to extract DNA from anything living page. [1]