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Lab Report cellular respiration.docx - Lab Report Practice....

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Lab ReportPractice. No:3Grade:JuniorName:Samantha Muñoz, Steven Reyes, and Camila Sánchez.Date:June 20th, 2021Class:“B”Theme:A study on how pH affects the anaerobic respiration of yeast(Saccharomycescerevisiae)using red cabbage (Brassica oleracea var. capitata f. rubra)as a pH indicator.Research Question:What is the optimal pH (2, 2.5, 4.5, 5, 5.5, 6.5, 12) in which yeast(Saccharomyces cerevisiae)can perform anaerobic cellular respiration and produce the mostethanol and carbon dioxide?1.EXPERIMENTAL DESIGN1.1. Introduction, aim and justification of the chosen topic.Cell respiration is one of the most important processes that our body performs, whereorganic compounds are broken down to release energy, which then can be used in the cell.(Allot& Mindorff , 2014).With the help of enzymes, the cell can contain the most amount of usableenergy called ATP (adenosine triphosphate). There are two types of cellular respiration: aerobic(using oxygen) and anaerobic (without oxygen). The products of aerobic cellular respiration areCO2+H2O+ Energy and in anaerobic cellular respiration are: Lactic acid + Energy (lactic acidfermentation) orCO2+ Ethanol + Energy (alcoholic fermentation). The factor of study,yeast(Saccharomyces cerevisiae),performs anaerobic cell respiration and gets the alcoholicfermentation. To be more precise it takes 1 molecule of glucose and transforms it into 2molecules ofCO2, 2 molecules of Ethanol and energy from 2 ATP is released. The understandingof this process is not only academically important but economically too. This type of cellularrespiration is used in bread making, as they use yeast(Saccharomyces cerevisiae)for the doughto grow. The production of carbon dioxide is going to make the dough bigger, the bread fluffierand the ethanol will evaporate during the cooking. There are many factors that affect theefficiency of this processsuch as temperature or pH. In this experiment we are going to test theoptimum pH in which yeast can perform at its best, by measuring the height of the bubbles that
are created due to the cellular respiration. The acids that we decided to use and bought in thelocal markets were lemon(Citrus X limon), orange(Citrus X sinensis),tomato(SolanumLycopersicon), celery (Apium graveolens)cucumber(Cucumis sativus), and green pepper(Capsicum annuum)because they are edible materials that in fact can be used for theoptimization of the bread making process. As far as we know the stated conditions in which yeastto work is a pH from 4.0-6.0 for this reason our control sample will be tape water (pH 6). As wegot along with the preliminary investigation, we found a lot of disagreements between stated pHof the acids that were going to be used. For this reason, in this procedure, it was decided to use anatural pH indicator, red cabbage(Brassica oleracea var. capitata f. rubra),for getting our owntested data. Why does the red cabbage (Brassica oleracea var. capitata f. rubra)work to serve asa pH indicator? Is becauseRed cabbage contains a water-soluble pigment calledanthocyaninthat changes colorwhen it is mixed with an acid or a base. The pigment turns red in acidic environments with a pHless than 7 and the pigment turns bluish green in alkaline (basic)environments with a pH greaterthan 7.

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