Hypothesis: The DNA extracted from the strawberry will be the greatest amount due to their softness and pulverization. They have large genomes being an octoploid. This means that they have eight of each type of chromosome in each cell. Thus, the strawberry should provide the most DNA.
Procedure: I used 40 mL of each fruit, this including strawberry, kiwi, and banana, to derive the DNA. I used 20 mL of the normal liquid Dawn detergent, which was a deep bluish color. I filled each test tube with 4 mL of the mixture of fruits. I used 1 mL of meat tenderizer to mix with each of my fruit mixtures. I filled the rest of the tube with 4 mL of ethyl alcohol. Then I measured how much DNA was formed.
Large amount of DNA clumped together at the top, small bubbles in between the different strands, pieces flowing into the rest of the mixture, thin, sections peeling from the cluster
DNA clumped in a small amount at the top, sticking to one side, small and big bubbles in between the strands, mostly clustered together
DNA split up throughout the tube, not clumped together at all, flowing randomly, white pieces, thin
Large amount of DNA clumped together at the top, not really sticking to one side, taking up the whole circumference of the tube, small bubbles in between the DNA strands, transparent white color
DNA clumped in a small amount at the top, sticking to one side of the tube, larger bubbles in between the strands, DNA breaking off into the rest of the mixture, creating a trail of DNA
DNA had the smallest amount, clumped at the top, sticking to one side of the tube, breaking off into the rest of the mixture
Large amount of DNA clumped to the top, small bubbles in between the strands, thick texture of the DNA, transparent white color
DNA clumped at the top, small amount, large bubbles in between the different strands of DNA, flowing into the mixture
DNA split up throughout the tube, most of it at the bottom of the alcohol, not clumped together, relatively small amount
DNA Observations (Side and Top View of DNA Test tube)
The grey areas are the places that contain DNA, and the different colors are the mixtures of the different fruits, the Dawn detergent, the meat tenderizer, the salt, and the ethyl alcohol. As is seen, the DNA in the banana test tube showed to be most prominent, followed by the DNA in the kiwi, and then the DNA in the strawberry.
The results of the lab followed the general procedure that the soap will help dissolve the phospholipid bilayers of the cell membranes and organelles. The salt is used to break up protein chains that bind to the around the nucleic acids. The alcohol is used to precipitate the DNA so that it is easily visible. The results show that the banana contains the most DNA, followed by the kiwi, and lastly the strawberry. This, however, does not concur with existing ideas that the strawberry should have the most DNA. Since a strawberry has a large genome, being an octoploid, it was expected that the most DNA would be extracted from it.
Bananas have triploid sets of chromosomes and kiwi has diploid sets of chromosomes, both of these being less than that of strawberries. This could signify that the strawberry was expected to have more DNA extracted than both of the other fruits. According to some researchers, this data could fit possibly make sense. It is not only the number of chromosomes that determines the amount of DNA in a cell but the length and thickness of the chromosomes. Since there is research that shows that there are several species of amphibians and plants that have more DNA per cell than human cells, then there is not entirely accurate to base the amount of DNA that will be extracted from a fruit on the amount of chromosomes the fruit contains.
In order to improve the reliability of my data, I could take measures to make sure that the data is both quantitative and qualitative. I could take this step in using a ruler to measure the exacted amount of DNA in the test tube. I could also do this by scooping the DNA out the test tubes and placing them into graduated cylinders to evaluate the mL amount of DNA. I would probably use a different alcohol and see what kind of effect it has on the DNA of the different fruits, or maybe even try it without using salt or a meat tenderizer.
To learn more about this question, I could compare data with the other people in my class to see if they got the same results. I could also go online and see what kinds of the same lab that I did created the same or different results. To further my investigation of the DNA in these fruits, I could find different methods of extracting the DNA, instead of just using soap and salt. This could potentially give me more accurate data that I could compare to the data achieved by this lab. If I repeated this investigation, I would put the mixture of soap and alcohol into a beaker, and use larger amounts, so it would be easier to see the DNA. This way, I will have a greater amount of data, which could possibly reveal a difference that this lab did not.
* scienceNOW, NOVA and NOVA. “NOVA and NOVA scienceNOW.” 2005. pbs.org. 10 November 2008 <http://www.pbs.org/wgbh/nova/teachers/activities/pdf/3214_01_nsn_01.pdf>.
* Silvert, D. “DNA Extraction from Fruit .” 11 April 2005. Ask A Scientist. 10 November 2008 <http://www.newton.dep.anl.gov/askasci/mole00/mole00596.htm>.
* Swezey, Robert. “Fruitful DNA Extraction.” 2000. Exploratorium. 10 November 2008 <http://www.exploratorium.edu/ti/human_body/dna.html>.