1. Effects of Corticosteroids on Saccharomyces cerevisiae Reproduction and Carbon Dioxide Production Michaella Crouch Aberdeen Central High School Purpose Hypothesis Methods Data Analysis 1) Measure out 7.00 grams of S. cerevisiae and 2.50 grams of sucrose, place both into a labeled empty gallon water jug, and swirl the mixture until the yeast is evenly distributed and no clumps remain on the bottom. This is the control; repeat this two more times. For the corticosteroids continue onto step 2. 2) Carefully crush each of the dexamethasone, methylprednisolone, and prednisone tablets into a weigh boat using the bottom of a small test tube (applying pressure and slightly twisting the tube prevents the tablet from shattering and leaving the weigh boat). Once the tablet is crushed into a fine powder, use kimwipe to brush off the powder left on the bottom of the test tube. For the other two tablets, place each mixture into the respected labeled empty gallon water jug. 2b) Repeat steps 1 and 2 for the other reaming corticosteroid tablets. 3) Connect the pressure sensors to the Vernier and open Loggerpro. 4) Fill a 1000 mL beaker with warm tap water (43°C - 46°C) and using a graduated cylinder measure out 200mL. Curve the weigh boats so that the water and crushed tablet will flow into the jug and carefully pour in the warm water. Repeat for every jug. 5) Cap the jugs with the pressure sensors with their respected labeled containers. 6) Wrap parafilm around the pressure sensors and the containers. 7) Collect the Pressure in each container every five minutes for three hours. Corticosteroids will affect the growth and carbon dioxide production of Saccharomyces cerevisiae (S. cerevisiae), due to corticosteroids chemical formulas being the closest to ergosterol which makes up S. cerevisiae membrane. Saccharomyces cerevisiae is the model for eukaryotic cells and the effect of corticosteroids may cause a dramatic increase in Saccharomyces cerevisiae reproduction, which could lead to a chance of DNA mutations. One-way ANOVA: Control, Prednisone, Prednisone, Methylprednisolone, Dexamethasone Source DF SS MS F P Factor 4 0.1715 0.0429 2.51 0.109 Error 10 0.1711 0.0171 Total 14 0.3427 S = 0.1308 R-Sq = 50.06% R-Sq(adj) = 30.08% Individual 95% CIs For Mean Based on Individual 95% CIs For Mean Based on Pooled StDev Pooled StDev Level N Mean StDev -----+---------+---------+---------+---- Control 3 1.0557 0.0535 (----------*---------) Prednisone 3 1.1820 0.1524 (----------*---------) Methylprednisolone 3 1.3453 0.1675 (---------*----------) Dexamethasone 3 1.3277 0.0907 (----------*---------) -----+---------+---------+---------+---- -----+---------+---------+---------+---- 0.96 1.12 1.28 1.44 0.96 1.12 1.28 1.44 Pooled StDev = 0.1308 Individual Value Plot of Control, Prednisone, Prednisone, Methylprednisolone, Dexamethasone A one way analysis of variance to evaluate the relationship between a Control, Prednisone, Methylprednisolone, and Dexamethasone on carbon dioxide pressure. the ANOVA was not significant with a P= 0.109 due to the ranges of each corticosteroid and the control overlapping. Materials Vernier Pressure Sensor Vernier Logger Pro Laptop Saccharomyces cerevisiae Sucrose 100 mL Graduated Cylinder 1000 mL beaker Gallon Water Jug (3) Test Tube Parafilm Weigh Boats Kimwipe Dexamethasone, Methylprednisolone, and Prednisone Tablets Raw Data Conclusion This experiment was conducted to determine if corticosteroids on Saccharomyces cerevisiae cause an increase in reproduction by measuring the carbon dioxide pressure. It was found that corticosteroids do not have a significant effect on yeast growth, which supports the null hypothesis. However, it was found that dexamethasone and methylprednisolone provide energy for S. cerevisiae for a longer period of time then prednisone and the control. Despite the fact that corticosteroids do not affect the overall growth rate of S. cerevisiae, they can provide a source of energy allowing cell reproduction over a greater period of time than normal. Discussion The ANOVA was not significant with a P= 0.109 due to the ranges of each corticosteroid and the control overlapping. As a result the null hypothesis supports that corticosteroids do not affect S. cerevisiae carbon dioxide production and growth. Yet when comparing the graphs to the mean there arises an unusual trend. Prednisone’s average carbon dioxide pressure increase is 1.182; the control’s pressure increase is 1.056. However, the methylprednisolone average carbon dioxide pressure increase is 1.345, and the dexamethasone is 1.328. It is possible that the methylprednisolone and dexamethasone is prolonged during reproduction which allows the yeast to grow longer, but at a slower pace than the prednisone and control, which are broken down more rapidly; therefore, the yeast have a quick but non-lasting growth spurt. Also, due to changes in room pressure the starting point was slightly different for each one. When this is taken into account, all four of the yeast’s carbon dioxide pressure production corresponds to the same pressure increase of roughly 4 kPa’s. The graphs show the carbon dioxide pressure over a three hour interval with measurements taken every five minutes. The carbon dioxide pressure was measured in kPa’s and the time in hours. Picture