Carbohydrates Lab Report

Background: Yeasts are eukaryotic, unicellular organisms that are members of the kingdom fungi. Without the presence of oxygen yeasts obtain energy though anaerobic respiration and through the processes of glycolysis and fermentation, convert carbohydrates into ATP, alcohols, and carbon dioxide (CO2). Yeasts are able to use many different carbohydrates to perform cellular respiration, though they mostly receive their energy from 6-carbon monosaccharides or disaccharides. Carbohydrates (sugars) are biological molecules consisting of carbon, hydrogen, and oxygen atoms. Carbohydrate sugars are divided into two majors groups, monosaccharides and polysaccharides. Monosaccharides (simple sugars) are the monomers of carbohydrates. These cannot be

6) 2 mL of the glucose solution was place in test tubes G1, G2, and G3.

7) The yeast suspension was swirled and 2 mL of the yeast suspension was placed in G1.

8) The test tube was placed in the water bath and the time was set to 10 minutes.

9) With 4 minutes remaining, steps 7-8 were repeated using G2.

10) (These steps must be done as quickly as possible)

a) When the 10- minute time frame elapsed, the G1 tube was removed from the incubator.

b) 1mL of the solution was transferred from G1 to the 250mL Nalgene bottle.

c) The CO2 sensor was placed firmly in the opening of the Nalgene bottle.

d) The concentration began being measured by pressing the collect button

11) When the data finished running, the data was stored by saving and making a screenshot of the data.

12) Before the time elapsed on the G2 test tube, the Nalgene bottle was thoroughly washed and dried using the paper towels.

13) The tip of the CO2 gas sensor was fanned using the hand for a minute and dried using paper towels.

14) Step 10 was repeated using the G2 test

While the lab did demonstrate that when the yeast was added to a solution of glucose, there was a high rate of respiration, it was sucrose that demonstrated the highest rate of respiration. As shown in figure 6, the CO2 concentration in the sucrose sample was the highest throughout the entire experimental period, with glucose being the second highest. The samples containing fructose and lactose and the third and fourth highest amounts respectively, and as expected there was very little respiration that occurred in the water. These results indicate that the rate of respiration is yeast is not related to the length of the sugar molecule. It is related to the identity of the sugar. Since sucrose is a disaccharide consisting of one glucose monomer and one fructose monomer, the data suggests that yeast are able to metabolize fructose very readily, however not they cannot metabolize it as well as the glucose. This is supported by the data in figure 6 while shows that the average CO2 concentration in the glucose solution was higher than the CO2 concentration in the fructose solution. Additionally the data did show that yeast can perform cellular respiration in all 4 forms of sugar and can even perform a slight amount of cellular respiration in water, however respiration is