Presentation on theme: "What Effect Do Ultraviolet Rays Have On Yeast Colony Growth?"— Presentation transcript:
1 What Effect Do Ultraviolet Rays Have On Yeast Colony Growth? By Katie SchneiderGrade 10Academy of Notre Dame de NamurTake out school.
2 ResearchUV-A light, specifically, is what mainly causes tanning, skin aging, and cataracts, UV-B causes sunburn, skin aging and skin cancer, and UV-C is the strongest, and therefore most effective at killing microorganisms. Sunburn is a short-term sign of UV damage, but skin aging and skin cancer are long-term effects of UV damage.I would make this multiple bullets.
3 ResearchUVA radiation specifically causes 2 types of DNA damage: cyclobutane pyrimidine dimers and 6-4 photoproducts, both of which cause bends in DNA structure, therefore hindering replication and transcription. These 2 types of damage are repaired by nucleotide excision repair, in which the damage is detected, the section of DNA that includes the damage is removed, and it is filled in with new DNA by DNA polymerase.Again – single words and multiple bullets.
4 ResearchIn this experiment, the Saccharomyces cerivisiae is genetically engineered to be DNA-repair-deficient. This means that the enzymes that normally would repair DNA damage are knocked out so that the yeast is especially sensitive to UV light. This helps to show what effect that gene has in yeast’s lives, and how fatal UV light would be if the DNA damage was not repaired.Too many words – single words – you are going to SAY the rest.
5 HypothesisIf yeast colonies are exposed to UV light for varied amounts of time, a short amount of UV exposure will aid in yeast production, but longer exposure will kill the yeast cells because of the damaging effects of UV light.
6 Materials UV-sensitive yeast strain Sterile dilution tubes Sterile toothpicksDextrose (YED)Petri dishesSterile distilled waterPipettesGlass spreading beadsWhere was yeast purchased? I would put materials on just one page – make two columns.
8 ProcedureThe agar plates were poured by heating sterile YED agar in a microwave then pouring the agar onto 25 petri dishesThe master plate was then streaked with yeastTo determine the optimal serial dilution needed for the experiment, 1:1,000 and 1:10,000 dilutions of a yeast suspension made from the growth on the master plate were testedThey showed no growth, so they were tested again, but without UV exposureThey again showed no growth, so 1:10 and 1:100 dilutions were testedThe 1:10 dilution provided growth that was too dense, so 1:100 dilution was used for actual experimentationPlastic test tubes and sterile bulb pipettes were then used to make the 1:100 serial dilution of the yeast suspension
9 Procedure2.5 mL of this suspension was pipetted into each petri dish, which was labeled either exposed or control for 1, 3, 5, or 7 minutes, with 3 trials for each5 glass beads were placed in each petri dish, which were swirled across the plate to spread the yeast suspensionThree holes were made across the middle of a cardboard box, and UV flashlights emitting light in the 385 nm range were places in the openingsThree petri dishes at a time were then exposed to the light for their indicated timesControls were covered in aluminum foil before being exposed to the UV lightThe exposed samples were then covered in aluminum foil, and stored in an incubator for 2 days at 30°C
10 ProcedureTo collect the data, a transparent grid containing 34 sections was placed over the petri dishThe number of sections containing yeast growth out of 34 was then recordedThere were 3 trials for each amount of time for control and exposedIndependent variable-the amount of time the yeast was exposed to UV lightDependent variable-the amount of yeast growthControl-the yeast not exposed to UV lightConstants-amount of yeast in each petri dish, sixe of the petri dishes,Make your variables a separate slide.
11 Number of Sections Showing Yeast Growth out of 34 DataNumber of Sections Showing Yeast Growth out of 34Trial #Control 1 minExposed 1 minControl 3 minExposed 3 minControl 5 minExposed 5 minControl 7 minExposed 7 min134183023226333Average2229213123
13 ConclusionHypothesis-“a short amount of time will aid in yeast production, but a longer amount of time will kill the yeast cells because of the damaging effects of UV light.”The results support the hypothesis, however, because of the high standard deviation, the results were proven to be unreliable.This experiment has relevance to the world today because UV light is a major cause of skin cancer, and extended exposure can be extremely detrimental to skin health.Other experiments regarding UV light could be conducted testing the strength of UV at different times of day, during different seasons, or for longer periods of time.You need a slide with sources of error.Watch the wording in bullet 2 (were proven to be unreliable – I would say that they may be unreliable – more trials are suggested).
14 ReferencesCells and DNA. (2011, October 17). Retrieved fromClancy, S. (2008). DNA Damage & Repair: Mechanisms for Maintaining DNAIntegrity. Retrieved from Nature Education database.Deoxyribonucleic Acid (DNA). (2011, March 23). Retrieved fromDNA damage from deamination and depurination [illustration]. (n.d.). Retrieved from Science Online database.Genetic Engineering. (2011, May 23). Retrieved fromGoodman, B., MA. (2011, October 6). UVA Radiation May Cause DNA Damage in Skin. Retrieved fromHighland, J. (n.d.). The Effects of UV Light on Yeast. Retrieved fromHockberger, P. E. (2002). History of Ultraviolet Photobiology. Retrieved from Department of Physiology, Feinberg School of Medicine, Northwestern University website:Kirkland, K., PhD. (2007). Infrared and Ultraviolet. In Light and Optics (pp ). New York: Facts On File, Inc.Liu, S., & Usinger, L. (n.d.). All About Agar. Retrieved fromMacNeal, R. J., MD. (2007, August). Overview of Sunlight and Skin Damage. Retrieved from Merck website:
15 ReferencesMaczulak, A. (n.d.). Saccharomyces. In Encyclopedia of Microbiology. Retrieved fromTanner, F. W., & Ryder, E. (1923, May). Action of Ultraviolet Light on Yeast-Like Fungi. Botanical Gazette, 75(3), 309. Retrieved fromTwyman, R. (2002, August 28). What are ‘model organisms’? Retrieved fromUltraviolet radiation and human health. (2009, December). Retrieved from World Health Organization database.Ultraviolet treatment for water suggested. (2010). Biofouling. Retrieved fromUltraviolet (UV) Radiation. (2010, August 17). Retrieved fromWhyte, D. B. (2009, December 4). Exploring DNA Damage: What Effect Do Ultraviolet Rays Have on Yeast Colony Growth? .Wyman, B., & Stevenson, H. L. (n.d.). Ultraviolet radiation–A range (UV-A). In The Facts On File Dictionary of Environmental Science, Third Edition. Retrieved fromWyman, B., & Stevenson, H. L. (n.d.). Ultraviolet radiation–B range (UV-B). In The Facts On File Dictionary of Environmental Science, Third Edition. Retrieved fromWyman, B., & Stevenson, H. L. (n.d.). Ultraviolet radiation–C range (UV-C). In The Facts On File Dictionary of Environmental Science, Third Edition. Retrieved from