*To make the extraction buffer, 100 ml of shampoo (without conditioner) was mixed with 15 g of NaCl and 900 ml of water.
Procedures Used in Experiment
Once all materials were gathered by group members, each individual group began their experiment. The first step was to place the strawberry or banana in the zip lock bag and smash the strawberry/banana for 2 minutes. The strawberry produced enough juice and water based substance that no added water was needed, however the banana did not produce as much juice and a small amount of water was added. The actual amount of water varied from group to group. The next step involved adding 10 ml of extraction buffer to the bag. This added even more water based substance to the bag of mashed fruit. The bag was then mashed again for one minute to mix in the buffer solution with the existing smashed fruit. The purpose for adding the extraction buffer was to break the cell walls and disrupt the cells so that all the material inside the cell would be loosed and extracted from the cell.
This material included organelles, cell walls, cell membranes, DNA, and all intercellular fluid. Once the minute was up, the coffee filter was made into a funnel shape and placed on top of the beaker to filter the solution into the beaker. The solution was filtered to remove seeds and cell debris such as cell membranes, organelles, proteins, and cell walls allowing only the DNA and small cell debris to filter through. The filtrate, or filtered solution from the bag, was then placed into a test tube. The test tube was filled approximately 1/8 full. Ice cold alcohol was poured into the test tube until the level of the tube was ½ full.
Pouring the alcohol into the filtrate caused the DNA to precipitate out of the solution. A distinguished difference in the solution was noticeable consisting of three parts. In the bottom of the tube existed the cell solution and was a red color. The alcohol was suspended above the cell solution and was clearer. Inside the alcohol solution the precipitated DNA was visible as mucus like substance. Using the wooden coffee stirrer, the DNA could be spooled out of the solution. All of the above steps were completed in the same manner for the banana DNA extraction except for the adding of water during the smashing of the fruit.
Observations and Results:
After the experiment a significant difference in the amount of precipitated DNA was visible in the strawberry test tube in comparison with the banana. This result could have been due to the amount of solution was present in the bag after the strawberry was mashed compared to the amount present in the banana bag. The obvious reason is that more DNA was extracted from the cells of the strawberry than from the cells of the banana.