Carbon dioxide

7 July 2016

In our lab this week we tried to see how different amounts of substrates affect our organism, yeast, in its fermentation process. Yeast (Saccharomyces cerevisiae) is an organism that is cultured for the cells themselves, as well as the end products that they produce during fermentation. Yeasts are commonly known for the ethanol fermentation due to their ability to produce ethanol for industrial purposes (Collins et al. , 2004). Yeast is also well known for their role in the manufacturing of beer, wine and liquors.

Another important aspect of yeasts is that their fermentation process is anaerobic so they are able to complete their process without the presence of oxygen (Collins et al. , 2004). There are two different forms of respiration for organisms that either require or do not require oxygen. The first form is cellular respiration which is aerobic, meaning oxygen is required to complete the process and at the end, lactic acid is produced. For organisms that do not have the capability of going through cellular respiration, they must use a process called fermentation which is an alternative source of enabling energy throughout an organism.

Carbon dioxide Essay Example

The dominant difference between the two sources is the amount of ATP that is produced. Fermentation produces an extremely low amount of ATP compared to cellular respiration (Mader 140-41, 2013). The reason why fermentation produces less ATP than cellular respiration is because fermentation fails to utilize oxygen with the pairing glucose. In cellular respiration 1 mole of glucose is combined with oxygen and produces 34-36 ATP. However, it fails to produce high amounts of carbon dioxide unlike fermentation. Fermentation lacks the source of oxygen with the 1 mole of glucose and is only able to produce 2 ATP.

Fermentation would have to cycle through 17 times to produce the same amount of end products that cellular respiration produces. In this experiment, we are tried to find out how to maximize the production of ethanol by evaluating different variables that are associated with fermentation. We hypothesized that by increasing the sugar concentration, it would provide more food for the yeast. As the yeast consumes more food, more CO2 (as seen through bubbles), will be produced which ultimately leads to a higher increase in the production of ethanol through fermentation.

Materials and Methods: We filled a plastic bottle with 100 mL of warm tap water and added a 1% concentration of yeast (1gram) and a 3% concentration of glucose (3 grams) to the water. A manometer was used to seal the bottle and measure the number of bubble that was given off by the mixture. A warm water bath was used to maintain a temperature of 43-46 degrees Celsius. The mixture went into the warm water bath and remained there until experiment was completed (See diagram 1).

We recorded the number of CO2 bubbles that were produced in five minute time increments for a half hour using an electronic bubble counter. The experimental part of the procedure was performed the same way as the controlled experiment, except the yeast to sugar ratio was changed to support our hypothesis. Instead of having a 3% concentration of glucose (3 grams), we used a 6% concentration of glucose (6 grams). Figure 1 Figure 1. The set up that was used to conduct the experiment for both the controlled and the experimental groups of the lab experiment. Results:

In the controlled part of the experiment we found that in a thirty minute time span, recorded in five minute increments, sixty-one carbon dioxide bubbles were produced (See Table 1). According to the results, as time passed and the decrease of temperature, the production of carbon dioxide bubbles decreased from a starting total of fourteen to a final total of seven (See Figure 2). In the experimental part of the lab, the numbers of bubbles were recorded in the same amount of time as the controlled experiment. Throughout the entire thirty minutes, the experimental group produced a total of 206 bubbles.

For the first half of the observation time, the experimental group peaked by producing forty-one carbon dioxide bubbles during the ten-fifteen minute observation time. In the second half the observation time, the production of carbon dioxide was decreased from forty-one bubble to thirty-eight. (See Figure 2). With the results we were able to see that our experimental group produced the most carbon dioxide and thus the most ethanol. Our experimental group was able to produce 206 total bubbles while the control group was only able to produce sixty-one (See Figure 3).

Table 1: Number of Carbon Dioxide Bubbles Produced Table 1 reflects the number of carbon dioxide bubbles produced in the experiment. The chart provides a side by side comparison between the two different experiments. The chart also shows which lab procedure had a higher success in producing the most amount of carbon dioxide. Figure 2 In figure 2 reflects the amount of carbon dioxide bubbles produced over a thirty minute time period between a controlled lab experiment ( 1% yeast, 3% glucose) and the experimental part of the procedure (1% yeast and 6% glucose).

Figure 3 Figure 3 visually represents the total number of carbon dioxide bubbles that was produced in the 30 minutes time period. The comparison is between the controlled group (3% glucose) and the experimental group (6% group). Discussion and Conclusion: For this lab experiment, we hypothesized that if we increased the amount of glucose in solution, it would result in a higher rate of fermentation, which means that it would produce more ethanol and carbon dioxide. After the two parts of the lab were conducted, we were able to find that our hypothesis held true.

In the controlled lab we were only able to produce 61 bubbles of carbon dioxide. When the experimental procedure was completed, we were able to produce 206 bubbles. Thus, we can conclude from our results that due to the increase of glucose, we were successfully able to increase the rate of fermentation and thus increase the production of ethanol and furthermore carbon dioxide. When looking at other fermentation labs involving glucose and yeast, the results were almost identical with the controlled experiment but differed with the experimental.

In the lab, “Fermentation, Respiration & Enzyme Specificity: A Simple Device & Key Experiments with yeast”, they started with a higher concentration of yeast and lower concentration of glucose. With their experiment they found that as the yeast consumes the glucose, CO2 production was increasing at a steady constant rate (Reinking et al 1994). This was different from our findings because we obtained the same results as they did, however we had a higher glucose concentration than yeast.

For this lab to accurately determine which variable controls the higher rate of fermentation, multiple variables (yeast, glucose, temperature, etc. ) needed to be tested at the same time. Instead of just choosing one variable to experiment, we should have tested two or three different variables which would have given us a much wider variety of data to compare and utilize in our hypothesis. Along with multiple test substrates, multiple test runs of each substrate should have been conducted. The more tests conducted on the same substrate, the more accurate results we would have found.

Being able to test different substrates for yeast fermentation at the same time is extremely important due to yeast’s industrial purposes as well as tying to utilize different fermentation techniques such as cell recycle and vacuum fermentation. . Yeast fermentation is used industrially specifically for their production of ethanol. Any industries such as the beer, wine, and liquor industry are constantly trying to determine an economically efficient way of producing ethanol (Cysewski et al 1978). If they could determine the fastest way of producing ethanol, it would give them a higher profit and be beneficial to the industry.

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