The Effect of Secondhand Smoke on Microbes. Bobby Kiernan Grade 9 Central Catholic High School

Transcription

1 The Effect of Secondhand Smoke on Microbes Bobby Kiernan Grade 9 Central Catholic High School

2 Problem Millions of people worldwide emit the secondhand smoke of tobacco from products such as cigarettes and cigars that could harm human cells.

3 Secondhand Smoke Smoke that is given off by the end of the smokers cigarette, as well as what the smoker exhales Detrimental to health Responsible for 3,000 lung cancer deaths annually of non-smokers Harmful to the growth and development of children and teens

4 Cigarettes Contain over 4,000 chemicals, many of which have been shown to be detrimental to human health Emit CO 2 Contains about 1 gram of tobacco and 8.5 grams of nicotine Responsible for 6 million deaths annually Contain mutagenic and carcinogenic substances Combustion products yield many harmful substances

5 Cigars Contain many similar chemicals and other components found in cigarettes that are known to affect human health Contain about 12 grams of tobacco and 250 grams of nicotine Cigar tobacco wrapped in dried tobacco, opposed to the paper that wraps cigarette tobacco

6 Camel Cigarette 100 millimeters 1 gram of tobacco, 8.5 milligrams of nicotine Has filter, but does not filter secondhand smoke Popular throughout the United States and the world

7 Don Sixto Cigar 140 millimeters Contain about 12 grams of tobacco, 250 milligrams of nicotine Wrapped in dried tobacco opposed to paper

8 Previous Studies Study carried out in U of California, Riverside 2004-tested the effect of secondhand smoke on the structure and function of fibroblasts: secondhand smoke delayed the repair of tissue because fibroblasts could not move into the wounded area. In the early 1980s, it was reported that non-smoking wives and children of smokers are twice as likely to die from lung cancer as those of wives and children in non-smoking households.

9 Yeast Saccharomyces cerevisiae The most studied eukaryotic cell Has many characteristics that are similar to those of human cells, like nutrition and cell growth Rely primarily on aerobic respiration to produce energy, thus if oxygen is reduced, growth rate declines as anaerobic metabolism is activated

10 Purpose Many people in the United States and all over the world smoke cigarettes and cigars. To determine if the secondhand smoke from tobacco products harm eukaryotic cells (microflora or human cells).

11 Hypotheses Null Hypothesis: Secondhand smoke from cigar and cigarettes will not significantly affect yeast survivorship. Alternative Hypothesis: The secondhand smoke from cigar and cigarette will significantly reduce the growth of yeast. Cigar secondhand smoke will have a greater impact of the survivorship of yeast than cigarette secondhand smoke.

12 Materials Saccharomyces cerevisiae YEPD media and agar plates (1% yeast extract, 2% glucose, 2% peptone) Sterile Dilution Fluid (100mM KH 2 PO 4, 100mM K 2 HPO 4, 10mM, MgSO 4, 1mM, NaCl) Sterile micropipettes and tips (1000 ml and 200 ml) Sharpie Spreader bar Ethyl alcohol Burner Sealed cardboard box Camel cigarettes containing about 1 gram of tobacco Cigar containing about 12 grams of tobacco Stop watch Incubator Klett spectrophotometer

13 Procedure 1. Saccharomyces cerevisiae was grown overnight in sterile YEPD media. 2. The culture was placed in an incubator (30 o C) until a density of 50 Klett spectrophotometer units were reached. This represents a density of approximately 10 7 cells/ml. 3. The culture was diluted in sterile dilution fluid to a concentration of 10 5 cells/ml.

14 Procedure µL of cell culture was then added to the test tubes, yielding a final volume of 10mLs and a cell density of approximately 10 3 cells/ml. 5. The solution was mixed by vortexing, evenly suspending the cells throughout the solution ml of the resulting solution was then pipetted onto YEPD agar plates, creating a cell density of about 100 cells/ml.

15 Procedure 7. The solution was evenly spread on the plates using a spreader bar sterilized with ethanol alcohol. 8. The plates were taped to the inside surface of a box top. The smoking product was lit and placed in an ashtray in the center of the box. The lid with the inverted exposed plates was placed on the top of the box. 9. The plates were exposed to the cigarette or cigar smoke for five minutes. 10. The plates were covered, and incubated at 30 C for 72 hours and the resulting colonies were counted.

16 Results Number of Yeast Colonies Average Yeast Survivorship Colonies Overall P-value: Control Cigarette Cigar Variable

17 Single Factor ANOVA SUMMARY Groups Count Sum Average Variance Column Column Column ANOVA Source of Variation SS df MS F P-value F crit Between Groups Within Groups Total

18 Dunnett s Test Group T-Value Significance Cigarettes 2.11 Not Significant Cigars 3.99 Significant

19 Conclusion The null hypothesis was accepted for the cigarette smoke. The null hypothesis was rejected for the cigar smoke. The alternative hypothesis is accepted for the cigar smoke, but rejected for the cigarette smoke. The second alternative hypothesis was accepted for the cigar smoke having a greater effect on survivorship. Dunnett s test showed that the amount of tobacco in cigar smoke did have a significant effect on yeast growth, but cigarette smoke did not.

20 Limitations The cardboard box was not completely air tight, meaning that some secondhand smoke from each product could escape. At the end of five minutes, when the plates were removed from the box, they were exposed to possible foreign bodies in the air. Could not exactly synchronize the plating so the yeast was spread at exactly the same time

21 Further Testing More replicates in each trial A wider variety of the amounts of tobacco Differing time increments Testing more types of microbes to see if tobacco has an effect on other forms of life Smoke affecting the growth rate of cells Synergistic effects

22 Sources History of Tobacco. From The First to the Last Ash: The History, Economics, and Dangers of Tobacco. December 22, of.html Effects of second-hand smoke on structure and function of fibroblasts BMC Cell Biology. December 22, Smoking-Effects on Your Body. Better Health Channel. December 20, > g_effects_on_your_body> Fibroblasts-What Are Fibroblasts? News Medical. December 22, Fibroblasts.aspx Baker s Yeast Cells-Our Relatives. Howard Hughes Medical Institute. December 20, Nicotine, Tar, and CO Content of Domestic Cigarettes. December 15, <