The Effect of Incubation Temperature on Incubation - Research Paper Example

The Effect of Incubation Temperature on Incubation Experimental Question Cellular respiration refers to a set of metabolic reactions and processes which occurs in the cells of plants and animals leading to the conversion of biochemical energy in the nutrients into adenosine triphosphate (ATP). It is also accompanied by the release of waste products. According to Rich, the reactions which take place in cellular respiration are catabolic and they lead to the breaking of large molecule into small molecules with energy being released (1089). Respiration is one of the key ways though which cells get energy used in fuelling of cellular activities. Cellular respiration is also considered to be an exothermic redox reaction due to the heat energy that is released in the process. Generally, the overall reactions takes place in a series of biochemical steps with most of these steps being redox reactions. Even through it is widely considered to be a form of combustion reaction, cellular respirations does not resemble an actual combustion reaction since there is a slow release of energy. Cellular respiration takes place through aerobic or anaerobic process. The process of aerobic respiration and formation normally starts with glycolysis. In aerobic respiration, the series of biochemical reactions take place in the presence of oxygen. On the other hand, fermentation involves the breaking down of the chemical bonds on the nutrients in the absence of oxygen. Knisely states that formation is a very quick process (87). However, it is a very inefficient process through which cells obtain energy for various cellular activities. In the absence of oxygen, cells use more glucose to generate the same amount of energy. There is also a difference in the ATP production level in the aerobic and the anaerobic processes. Facultative anaerobes normally respire through aerobic respiration. However, they also have the ability to resort to fermentation or anaerobic respiration when the oxygen conditions become deficient. Yeast is an example of a facultative anaerobe which produces ethanol when it undergoes fermentation. In the presence of oxygen, yeast cells undergo aerobic respiration to produce carbon dioxide, water and ATP. C6H12O6 + 6 O2  6 CO2 + 6 H2O + 36 ATP When there is insufficient oxygen in the environment, yeast cells undergoes fermentation where the glucose undergoes glycolysis leading to the production of pyruvate molecules and NADH +H+. The pyruvate molecule is then converted to acetaldehyde which will later one be transformed into ethanol. As the conversion takes place, NADH is oxidized back to NAD+ which can be regenerated and reused in the glycolysis process. This is what allows the fermentation cycle to continue. The fermentation equation which takes place when the yeast cells lack sufficient oxygen can be understood on the basis of the equation shown below. C6H12O6  2 CH3CH2OH + 2 CO2 + 2 ATP Just like in most other biochemical process in plants and animals, cellular respiration is affected and influenced by several factors. Lubert notes that temperature, the composition of nutrients, availability of enzymes and type of organism will not only affect the rate at which cellular respiration takes place but also the amount of waste that will be released (65). The purpose of this experiment is to explore the degree of fermentation occurring under different incubation temperatures. This will be done by observing the carbon dioxide which produced as yeast ferments sugar. Different incubations temperature will be used and the amount of carbon dioxide that is produced measured so comparison can be done. In this experiment, the hypothesis is that yeast will undergo fermentation process in the absence of oxygen. The fermentation will take place after the years has used the available limited amount of oxygen in the experiment media used. In all the experiment set ups where different incubation temperature have been used, carbon dioxide will be produced as a product of the fermentation process. The amount of carbon dioxide produced in the various experimental set up is expected to vary with the incubation temperature being considered. Experimental Design In order to determine the extent of fermentation which takes place in yeast, two types of variables will be used. They will be the independent variable and the dependent variable. The dependent variable in this case refers to the experimental variable or the factor which is being tested. As stated earlier, the experiment is meant to determine the degree of fermentation yeast and different incubation temperatures. The incubation temperature in each of the set ups will therefore been the independent variable. The second type of variable is the dependent variable. Brand defines the dependent variable in a biological experiments to be the factor that is being measured to determine the whether the independent or the experimental variable has some effect on the subject (380). In this case, the degree of fermentation is being measured to determine the effect that the incubation temperature has on cellular respiration. The dependent variable is the rate or degree of fermentation in the yeast. To be able to achieve the objective of the study, there is need to operationalize the dependent variable so that quantifiable data can be collected. To measure the degree of fermentation in the yeast, the operational value for the degree of fermentation will be take to be the amount of carbon dioxide which is realized from the respiration process. Control Group Yeast is a facultative anaerobe which uses aerobic respiration process to obtain energy for cellular activities but resorts to fermentation when oxygen is not sufficient within the cellular environment. It has also been hypothesized in this present study that the degree of fermentation which will take place when the yeast is used in the experiments varies with the incubation temperature. As a result, there is need to have a control experiment which will act as a baseline to be used in comparing the results from the other experimental set ups. The control group in this particular experiment will contain yeast that has not been subjected to any incubation process. The yeast will be taken directly from where it had been kept and used in the experimental set up. From the control group that will be designed and set up, changes in the amount of carbon dioxide will be noted. In is however worth noting that the effect of temperature on the carbon dioxide released will have been negated by the fact that the yeast is not incubated. Experimental Group Experimental group refers to the group or subject in the experiments that are exposed to the variable which is being studied. In the current study, an investigation is being done to unravel the effect that the incubation temperature has on the fermentation process. This will be key in understanding how temperature affects cellular respiration in yeast and other facultative aerobes. The experimental groups in this case will have set ups containing yeast which has been exposed to both glucose and different incubation temperatures. Before the start of the experiment, the yeast to be used will be subjected to different temperatures for a specific period of time. After the incubation is successfully done, the yeast will be placed in the experimental media and the degree of fermentation measured on the basis of the amount of carbon dioxide that has been released from the fermentation process. Methods and Materials Materials To meet the goals of this experiment and clearly demonstrate effect that incubation temperature has on the rate of fermentation in yeast, several materials and equipment will be required. The materials need to be prepared in advanced so that the experimental procedure can be implemented smoothly. Sugar (Glucose) 2 packets of activated dry yeast Distilled or spring water Fermentation tubes (In case the fermentation tubes are not available, plastic graduated test tubes and a large glass test tube can be used) Beaker Test tube rack Balance 2 200 ML glass flask 100 ML glass or plastic graduated cylinder Hot plate Procedure While doing the experiment, care must be taken when handling the equipment and material which are to be used in achieve the objectives of the study. This will be key in ensuring that experimental errors are minimized. Moreover, it will ensure that the safety of the person carrying the experiment is guaranteed. Finally, the materials should be handle well so that the state they are in is not changed or alerted in a way which will negatively impact on the reliability, validity and credibility of the results obtained on the basis of the data which will be collected. 1. The experiment starts with the preparation of 10 percent sugar solution using the distilled water. It is worth noting that yeast only ferments in glucose. It is for this reason that the solution has to be made from glucose and not lactose or sucralose or any other artificial sweetener 2. The yeast suspension must be prepared a few minutes before the start of the experiment a. Measure 80 ML of the distilled water or the spring water. To the distilled water, add 7g of the yeast. This is approximately 1 packet of the activated dry yeast. This volume will be sufficient for all the five experiments which are to be set up. b. To activate the yeast, swirl it for one to two minutes. While doing so, ensure that the yeast is distributed evenly in the suspension. When clumps are present in the suspension, inconsistent results will be obtained. In each of the subsequent set ups, the swirling will be done in order to enhance the validity and the reliability of the data collected in the experiment. c. Measure 15 ML of the yeast suspension and heat it so that it can attain a temperature of 10 Degrees Celsius. This is meant to help incubate the yeast before it is used in the experiment. 3. Dilute the yeast with the sugar solution by using one portion of the distilled water and one portion of the yeast solution. When this is done, the sugar concentration in the solution created will be 5 percent. 4. Transfer the created mixture of yeast suspension and glucose solution to a fermenting tube. Invert the large glass tube as well as the slide over the graduated tube. While firmly holding the tubes together, invert the apparatus so that the large tube is in a n upright position as shown in figure 1. A small portion of the yeast suspension will most likely flow out of the gradated tube creating some bubbles at the top of the tube. 5. The set up should be left in place for twenty minutes after which the amount of carbon dioxide collected in the graduated tube observed and measured. The amount of generated carbon dioxide can be obtained by subtracting the initial volume of the air bubble from the final air bubble volume in the tube. 6. The first set up should be marked as “Set up 1”. As similar procedure should be followed for the second, third, fourth and fifth set ups. The only change will be in the incubation temperature. In the second set up, the suspension will be heated for 15 minutes. In the third, fourth and fifth setup, the suspension will be heated for 20, 25 and 30 minutes respectively. 7. The final set up (Control Group) will help in measuring the amount of carbon dioxide released in the control experiment. The steps which were followed in all the other set ups will followed except that no incubation will be needed. The yeast suspension will not be heated. Observation will be made on the changes in the set up just like it was done in the other five set ups. 8. The observations made in the set ups and the amount of carbon dioxide in each o the set ups should be recorded down in a table. Experiment Set-up of experiment Fig 1: Fermentation Tube Preparing for the experiments entails making sure that all the requirements and the materials needed are in place. This can take approximately one to two days depending on the available of yeast. With all the materials and requirements in place, the experiment can be conducted in a single session or is as series of session until all the different procedures are completed. If the experiment is to be conducted in a single session, each set up will require about one hour for preparing the yeast suspension, incubating the mixture and the actual set up. Since the entire experiment requires doing six independent set ups, it may be difficult to complete it in a single session. The most appropriate approach is dividing it into in two separate sessions. The first session will involve the first and the second experimental set ups or processes with the second session taking care of the third, fourth and the fifth set ups. All the set ups will use a similar procedure with the only difference being the incubation temperature. From each of the setups, the amount of carbon dioxide realized during the fermentation process is to be measured. It is on the basis of the measured volume of carbon dioxide that the degree of fermentation will be known. The analysis will rely on the assumption that the amount of carbon dioxide released will be directly proportional to the degree of fermentation. Data collection When yeast is put in a container with glucose or any other natural sugar which can be easily broken down, the cells respire even in the absence of sufficient oxygen. In the process, carbon dioxide and water is released. Some of the carbon dioxide that is generated will be trapped in the heats suspension while others will be released to the surrounding. The released carbon dioxide moves away form the yeast and occupies the space on the upper part of the graduated glass tube used in the experiment. It is the amount of bubbles which will show the degree of respiration. The faster the respiration, the larger the volume of gas seen in the graduated cylinder. To understand how temperature affects the process, it is imperative to accurately measure the actual amount of gas released in each of the six set ups. The data collection process entails noting the original volume of the bubbles in the graduated tube and then recording the amount or volume of bubbles in the upper section of the gradated cylinder twenty minutes after the setup is completed. With the initial and final volumes noted, it is possible to determine the amount of air or carbon dioxide that has been added to the cylinder during the fermentation process by working out the difference between the two figures. A similar process should be followed for the five other set ups with all the final and initial volumes being recorded down in similar manner. The volume of carbon dioxide produced in the control set up can also be obtain by working the difference between the final and the initial air bubble volumes. The data from the control experiment will be used as a baseline for comparing the volumes obtained from the other five set ups. Works Cited Brand, Mike. Mitochondrial Proton Conductance and H+/O ratio are independent of Electron Transport Rate in Isolated Hepatocytes". The Biochemical Journal 310. 2 (2003):379– 382.  Knisely, Karin. A Student Handbook for Writing in Biology. New York: Associates, Inc., 2002. Print. Lubert, Paul. Biochemistry. New York: W. H. Freeman and Company, 2004. Print. Rich, Paul. "The Molecular Machinery of Keilin's respiratory Chain". Biochemical Society Transactions 31. 43 (2003): 1095–1105.  Read More