Home detergents and DNA extraction from fruit Dana Hogan

Problem Testing which home detergent- shampoo, laundry detergent, or dishwashing detergent- most effectively extracts DNA from kiwi

Research DNA, or deoxyribonucleic acid, is the genetic material for all living things that can be found in the cell nucleus. DNA extraction is the removal of deoxyribonucleic acid from the cells or viruses in which it can normally be found. In a basic DNA extraction, the steps included: lyses of tissue and/or cells, precipitating the DNA, the application of a detergent, and heat denaturation. The kiwifruit, or Actinidia deliciosa, is made-up mainly of sugar and ascorbic acid. A surfactant, a main component of cleaning detergents, is a substance that has the ability to remove dirt, grease, or oil from other surfaces when it is added to water. Previous student studies on the subject of the effectiveness of home detergents and DNA extraction from fruit found that laundry detergent proved the most effective.

Hypothesis If the effectiveness of shampoo, laundry detergent, and dishwashing detergent in DNA extraction from fruit were tested, then dishwashing detergent would prove the most effective.

Materials pH paper 8g salt Glass stirring rod 200mL cold ethanol 500mL beaker Small metal hook Volumetric flask 100mL graduated cylinder Weighing paper Freezer 6 200mL beakers Balance weighing to .01g Hot water bath Balance weighing to .001g Thermometer 2 large Tupperware containers Small blender Fork and knife Ice 480g mashed kiwi Cheesecloth 20mL Suave® shampoo Coffee filters 20mL all® laundry detergent 6 1000mL beakers Filter 20mL Seventh Generation™ dishwashing detergent Strainer 10mL graduated cylinder 360mL distilled water 20 test tubes

Procedure PH balance of detergents was tested. A salt-water solution of 180mL of water and 4g of salt was prepared. 60g mashed kiwi were poured into a 200mL beaker and researcher 10mL detergent and 30g salt-water solution were added. Mixture heated in hot water bath at 50ºC for 10 minutes, stirring occasionally. Mixture transferred to ice bath for 5 minutes. Cooled mixture was filtered into 1000ml beaker. (In first set of trials, cheesecloth was used for filtration, whereas in the second set of trials, coffee filters were used for filtration.) Once 15mL of filtrated were gathered, 3 test tubes with 5mL of filtrate each were filled. 10mL of cold ethanol were carefully poured into each test tube. Test tubes placed in ice bath for 5 minutes. Spooling of visible DNA was attempted. Spooled DNA was spread onto pre-weighed weighing paper and let dry for 2 days. Mass of DNA extracted was calculated. This procedure was repeated twice for shampoo and dishwashing detergent samples. In the first set of trials, 1 control sample was tested, but in the second set of trials, 3 control samples were tested. In first set of trials, 3 samples of laundry detergent were tested, but in the second set, 1 sample was tested.

Variables Independent variable- type of detergent added Dependent variable- amount of DNA extracted Control- samples without detergent Constants- amount of salt-water, kiwi, and detergent added, temperature during incubation, length of time allotted for incubation and cooling, amount of filtrate used, amount of ethanol added to filtrate

Data DNA Extracted from Each Sample (g) Control Shampoo Laundry Dish (1) Dish (2) Trail 1 0.01 0.124 Trial 2 0.02 0.099 Trial 3 0.095 Average 0.106

Data

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Conclusion The purpose of this experiment was to see which home detergent- shampoo, laundry detergent, or dishwashing detergent- would most effectively extract DNA from fruit. The hypothesis that if the effectiveness of shampoo, laundry detergent, and dishwashing detergent in DNA extraction from fruit were tested, then dishwashing detergent would prove the most effective was supported. Knowledge gained through this experiment can help find more cost effective methods of DNA extraction for various purposes, whether it is in schools or advanced laboratories.

Discussion Possible errors that occurred during experimentation include different filtration methods, varying methods for mashing the kiwi, and the temperature of the ethanol. If repeated, more samples would be tested, coffee filters would consistently be used as the method of filtration, a balance measuring to .001 would be consistently used, and the ethanol would remain in the freezer up until it was needed. Further experimentation could include testing different types of fruits and organic vs. nonorganic detergents.

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