J. Ulises Gomez
Department of Biology, The University of Texas-Pan American, Edinburg, Texas 78539
October 29, 2010
Abstract.--Data shows that the yield of yeast cells looks affected by the presence of an antibiotic that decreases the yields of yeast cells. This behavior is unknown, because since antibiotics kill bacteria and yeastare not bacteria. It needs to be proved if there is an actual difference in the yield of the cells in the two types of yeast. Data has been recorded from each culture, where various calculations were made (Mean, Variance, Standard Deviation, Standard Error and t-Statistics). It has been found that there is a probability that a null hypothesis could be accepted, because of the results. A newhypothesis was formulated stating the similarity growth and characteristics of the yeast and bacteria.
The ultimate goal of science is to understand the natural world from scientific theories that link hypotheses well supported and have a common relationship. The process of science is described with base of the scientific method. All approach their assignments and work in different ways,even in a fortuitous way. From decades it has been discussed about the use of yeasts in fermentation since centuries. Consumption of baker's yeast (S. cerevisiae) as food in Germany during World War I increased its importance. Since then, rapid development took place in biotechnological applications of S. cerevisiae, as far as culture development, process optimization and scale up of products areconcerned. World production of yeast biomass is of the order of 0.4 million metric tonnes per annum including 0.2 million tonnes baker's yeast alone. In this research, it is going to perform various tests to the yeast cells, to see whether the 2 samples were taken from the same or different culture. Depending on the results we will accept or reject the null hypothesis.
Material and Method
Toperform this experiment it will be required two samples of yeast; one is going to be treated with antibiotic (A) and the other without the antibiotic (B control). A clean and dry hermacytometer will be required, then draw some of the yeast A and put it in the edge of the hermacytometer with a pipette without flooding it. After done that, place the hermacytometer on the microscope and use 4X lens tofind the 4 areas or Q sections of the hermacytometer (Q for quadrant). Each section has a volume of 0.1 mm x 1.0 mm x 1.0 mm = 0.1 mm3. Set the lens to 10X. Then start counting the cells on each Q section and record them in the data sheet, when done counting with culture A, rinse and dry the equipment and repeat the steps with culture B. Once recorded all the data, keep the information on asheet of paper
Record the data of the cell counting from various performances of the same test. To start the calculations it will be required to find the arithmetic mean of each culture, we will need to add all the values recorded from each culture and divided by the number of posted results. Knowing the arithmetic mean it can be find the variance, standard deviation and standard error. Varianceis a measure of the spread of a set of values around a mean, to find it, it is needed to sum each measured value of each culture, minus the arithmetic mean, square the result and divided by the arithmetic mean minus one. The Standard Deviation is the root square of the variance (S) = √ S2. The Standard Error of the mean describes how much variability is associated with the mean, to find it youneed to the standard deviation of each culture divides by the mean (SE) = S/ √N.
The final steps are to find the t-statistics, to do that subtract the mean of culture A minus the mean of culture B divided by the standard error of both means. In order to accept or reject the null hypothesis, compare the t-statistics results with the fixed values of the t-table. It is needed to know the...