Extracting Dna from Strawberry

Extracting DNA from strawberry

  The extraction solution is necessary to extract the DNA from strawberry. So, the main materials are the dish soup, salt and water.

  Dish soap is used to break the cell membrane of strawberries because the function of dish soap is consisting of hydrophilic and hydrophobic end which means it can easily break the cell membrane and nuclear membrane (Phospholipid bilayer). The DNA will be exposed to the extracting solution due to dish soap. The use of salt is to neutralize the charge in DNA (sugar phosphate backbone). The process is salt will be electrolyzed to Na+ and Cl- after it dissolve in water. Na+ is used to attract the PO3- in the DNA (Negative charged group in nucleic acid) which means it can let the molecules have less charge. So, the DNA will be separated out of the solution because of the molecules are less soluble in water. By the way, the water is a good solvent because it is polar and it can help salt to dissolve (electrolyze).

  Here are the steps to do this experiment. Firstly, use the graduated cylinder to measure 40ml water and 5 ml dish soap, then use the electronic scale to measure 5g salt. (make sure to delete mass of breaker). Mix all the materials together in another breaker and shake the breaker to make sure the salt to dissolve into water. Secondly, make strawberries (without leaves) to the thick liquid (smash it as jam through the plastic bag). Then add approximately 20ml extraction solution into the bag (if the strawberry puree is not juicy, add more extraction solution), wait for 5 minutes to let the reaction begin (Dish soap breaks the cell membrane, salt make the DNA less soluble). Thirdly, build a filter system to filter the mixture. (Fold the filter paper 4 times to shape it as a cone and place it into a funnel, make sure the side of paper completely stuck on the funnel). Do not surpass the height of the filter paper because the mixture will permeate through the clearance of filter paper. After the filter complete, add 1/5 test tube refrigerated cold ethanol into the mixture of strawberry juice. Then the DNA will be seemed very clearly on the surface of the solution. The cold ethanol has a low dielectric constant (24.5) and water has a high dielectric constant (78.5). The dielectric constant is a property that the ability of a substance to hold an electric charge. As the ethanol has a lower dielectric constant than water, it will make the nucleic acid less hydrophilic and cause it to drop out of solution. So, the DNA (with charge) will be separated from the solution.