In this experiment, we will explore fermentation. As you read Chapter 13, one of

Question

In this experiment, we will explore fermentation. As you read Chapter 13, one of the fates of pyruvic acid can be the production of carbon dioxide and ethanol. The pyruvic acid is made from carbohydrate by glycolysis. By measuring the amount of CO2 made over time, you can measure the efficiency of glycolysis. The basic experiment is relatively simple. 1. Prepare a sample of carbohydrate in water. Take note of the concentration in % (use volume or weight). 2. Completely fill a small juice glass with the carbohydrate mixture. 3. Add yeast to the mixture. Start with 1.4 tsp. 4. Mix the carbohydrate, water, yeast mixture. If you spill some make sure the juice glass is filled to the brim. 5. Place a flat-bottom bowl over the juice glass. 6. Invert both the bowl and juice glass together, being careful not to spill the contents. Now the glass is upside down in the bowl. 7. Watch the glass for at least 2 hours, recording the size of the bubble formed every 15 minutes. The size of the bubble can be estimated by measuring the height of the bubble in cm. Multiply the height by (1/4)x(diameter in cm)x(diameter in cm) x pi. Pi is approximate 3.14. (V= h x pi x r^2). Run this experiment 4 times (Since there is a lot of waiting, you can start a second experiment after you get the first started). One experiment should be a control, using no carbohydrate. Vary only one variable. For example, one student might test sucrose (table sugar), Karo syrup, and honey. Another student might vary the concentration of carbohydrate; 5%, 10%, 15%. Another student might vary the temperature: in an ice bath, room temp, in a 100 degree F oven. This is a case where I would like to see you design your own experiment. Make a lab report of your own design. It should have the following components:

1. Introduction and Objectives.

2. Procedure (What did you do?).

3. Results in tabular form.

4. Conclusion ( What do your results mean in terms of what you have learned about enzyme kinetics, glycolysis, and carbohydrate metabolism?)

Explanation / Answer

Hi,
Objective: To study the fermentation of carbohydrate by yeast

Introduction: The yeasts can ferment the carbohydrates in the absence of oxygen. The most common yeast fermented products are bear, wine...etc. The fermentation process depends on absence of oxygen, right temperature and also on the type of carbohydrate. The yeasts cannot ferment glucose or fructose. They can ferment sucrose, startch...etc. The fermentation process often produces alcohol and CO2 gas, which is often an indicator of successfull fermentation.

Procedure:
1. Two glasses were taken and named as T1, T2 and C1 and C2.
2. In the glasses named T1 and T2 the sucrose solution was filled till the brim . Concentration of sucrose = 5%.
3. The control glasses were filled with only water.
4. Add the yeast to all the glasses and place a flat bottomed bowl on top. Invert the glass and bowl, carefully.
5. Place the T1 and C1 at 37C incubator and C2, T2 in the efrigerator at 4C.
6. Observe the gas bubble on top and note the height.

Results:

Conclusion:

The gas formation was observed only in the T1 kept at 37C. The yeast could not ferment the sucrose in cold temperature. The enzyme invertase which ferments th sucrose works most efficiently at 37C and not in the cold. In the T1 the gas bubbles indicate the fermentation is sucesfull. The CO2 released from the anaerobic reactions where the sucrose is broken down to glucose and fructose and enters the glycolysis. At the end of glycolysis, pyruvat is formaed, which is converted into alcohol and Co2 with the release of 2ATP.

Time(min) T1 C1 T2 C2 15 No gas No gas No gas No gas 30 1 bubble No gas No gas No gas 45 2 bubble No gas No gas No gas 60 5 bubble No gas No gas No gas 75 4 bubble No gas No gas No gas 90 3 bubble No gas No gas No gas 105 6 bubble No gas No gas No gas 120 5 bubble No gas No gas No gas

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