Extraction of DNA from Fruit
Observing DNA in the Lab
- This is not a core practical but still a worthwhile experiment
- The molecular appearance of DNA is very familiar, but can we actually extract this important molecule from cells and look at it?
- DNA can actually be extracted from fruit using some basic classroom equipment
- Fruits that have relatively large amounts of DNA in their cells
- Strawberries, bananas and kiwis can be used
Method
- Mash the fruit and mix this into a beaker containing a solution of detergent (e.g. washing up liquid) and salt
- The detergent breaks down the cell membranes (and the nuclear membranes), causing the fruit cells to release their DNA
- The salt causes the DNA to stick together
- Filter the mixture into a test tube
- This removes any debris (big, insoluble bits of cell) from the mixture
- Gently add some ice-cold ethanol to the filtrate (the filtered mixture) by pouring the ethanol slowly down the side of the test tube
- This causes the DNA to precipitate (i.e. to come out of solution) as DNA is not soluble in cold alcohol
- The DNA will appear as a stringy white precipitate (a solid)
- If needed, this precipitate can be carefully extracted using a glass rod
A simple method for extracting DNA from fruit
