BIO 181L Lecture Notes - Lecture 10: Sucrase, Test Tube, Lactase
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Experiment 1 Fermentation by Yeast Experiment Inventory Labware (4) 250 mL Beakers (1) 100 mL Graduated Cylinder (1) Test Tube Rack (5) Fermentation Tubes = (10) Test Tubes (5 plastic and 5 glass; see Figure 4) (1) Measuring Spoon (4) Pipettes (1) Ruler Note: You must provide the materials listed in *red. EXPERIMENT 1: FERMENTATION BY YEAST Yeast cells produce ethanol, C2 H6 O, and carbon dioxide, CO2 , during alcoholic fermentation. In this experiment, you will measure the production of CO2 to determine the rate of fermentation in the presence of different carbohydrates with fermentation tubes. Note: Regular table sugar is sucrose, a disaccharide, which is made up of glucose and fructose. Glucose is a monosaccharide. Figure 4: Fermentation tubes. Note how the smaller, plastic test tube is inverted into the larger glass tube. You will create five fermentation tubes in this experiment. PROCEDURE 1. In this experiment, you will mix yeast with sugar, Equal®, and Splenda®. Before you begin, develop a hypothesis predicting what will happen when the sugar/sweeteners are mixed with yeast. Will fermentation occur? Why or why not? Record your hypothesis in the post-lab questions. 2. Use the permanent marker to label three 250 mL beakers as Equal®, Splenda®, and Sugar. 3. Empty the Equal®, Splenda®, and Sugar packets into the corresponding beakers. 4. Fill the Equal® and Splenda® beakers to the 100 mL mark with warm tap water. 5. Fill the Sugar beaker to the 200 mL mark with warm tap water. 6. Mix each beaker thoroughly by pipetting the solution up and down several times. Use a new pipette to mix each solution. Each beaker now contains a 1% solution. Set these aside for later use. 7. Completely fill one of the smaller plastic tubes with tap water and invert the larger glass tube over it. Push the small tube up into the larger tube until the top connects with the bottom of the inverted tube. Invert the fermentation tube (Figure 4) so that the larger tube is upright (there should be a small bubble at the top of the internal tube). Note: Repeat Step 7 several times as practice. Strive for the smallest bubble possible. When you feel comfortable with this technique, empty the test tube(s) and proceed to Step 8. CAUTION: Do not try to force the plastic test tube into the glass test tube. This might cause your glass test tube to break, causing you injury. If your plastic test tubes do not fit easily, please call eScience Labs for replacement glass tubes. If you are able to set up at least two fermentation tubes, continue with the experiment, but know that you will have to perform steps 12-15 in multiple steps. 8. Use the permanent marker to label the fourth 250 mL beaker as Yeast. 9. Fill this beaker with 175 mL of warm tap water. It should be between 30 and 40o C (warm to the touch). 10.Open the yeast package, and use the measuring spoon to measure and pour 1 tsp. yeast into the beaker. Pipette the solution up and down until all of the yeast is mixed homogenously into the solution. Note: Make sure the yeast solution remains homogenous before each test tube is filled in the proceeding steps. The yeast density is fairly high, and the yeast may settle to the bottom of the beaker if it rests for an extended period of time. 11. Use the permanent marker to label the big glass and small plastic test tubes as 1, 2, 3, 4, and 5. 12.Use the 100 mL graduated cylinder to measure and pour 15 mL of the following solutions into the corresponding small plastic test tubes: Tube 1: 1% Glucose Solution Tube 2: 1% Sucrose Solution Tube 3: 1% Equal® Solution Tube 4: 1% Splenda® Solution Tube 5: 1% Sugar Solution Note: Thoroughly rinse the graduated cylinder between each measurement. 13.Fill the remaining volume in each small tube to the top with the yeast solution. 14.Slide the corresponding larger tube over the small tube and invert it as practiced in Step 7. This will mix the yeast and sugar/sweetener solutions. 15.Place the fermentation tubes in the test tube rack, and use a ruler to measure (in millimeters) the initial air space in the rounded bottom of the internal tube. Record these values in the Table 1. 16.Allow the test tubes to sit in a warm place (approximately 30 °C) for two hours. Placement suggestions include: a sunny window sill, atop (not in!) a warm oven heated to approximately 85 °C (185 °F on an oven setting), or under a very bright (warm) light. 17.At the end of the fermentation period, use your ruler to measure (in millimeters) the final gas height (total air space) in each tube. Record this data in Table 1. 18.Calculate the difference between the initial and final gas height in each tube. Record this data in Table 1.
EXPERIMENT 1: FERMENTATION BY YEAST
Result Tables
Table 1: Yeast Fermentation Data
| Tube | Initial Gas Height (mm) | Final Gas Height (mm) | Net Change (mm) |
|---|---|---|---|
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | |||
| 5 |
Post-Lab Questions
Include your hypothesis from Step 1 here. Be sure to include at least one piece of scientific reasoning in your hypothesis to support your predictions.
Did you notice a difference in the rate of respiration between the various sugars? Did the artificial sugar provide a good starting material for fermentation?
Was anaerobic fermentation occurring? How do you know (use scientific reasoning)?
If you observed respiration, identify the gas that was produced. Suggest two methods you could use for positively identifying this gas.
Hypothesize why some of the sugar or sweetener solutions were not metabolized, while others were. Research the chemical formula of Equal® and Splenda® and explain how it would affect yeast respiration.
How do the results of this experiment relate to the role yeast plays in baking?
What would you expect to see if the yeast cell metabolism slowed down? How could this be done?
Indicate sources of error and suggest improvement (for example, what types of controls could be added?).
CELL RESPIRATION LAB
Section:
Type in your answers in complete sentences, be precise and specific to earn full credit, reformat if necessary
Purpose: The purpose of this lab activity is to analyze the effect of exercise on cellular respiration
Experiment 1 Enzymes in Food
Why is cellular respiration necessary for living organisms?
Why is fermentation less effective then respiration?
List the two co-enzymes involved in cellular respiration and describe their role.
| How many ATP molecules are produced in | |||
| Glycolysis | Citric Acid Cycle | Electron Transport | Fermentation |
Table 1. Fermentation by Yeast
| Tube | Initial Gas (mm) | Final Gas (mm) | Net Change |
| 1% Glucose Solution | |||
| 1% Sucrose Solution | |||
| 1% Equal Solution | |||
| 1% Splenda Solution | |||
| 1% Sugar Solution |
Include your hypothesis for this experiment. Be specificâ¦in other words we sure to include at least one end point you will measure to support your predictions. Natural sugar causes fermentation by producing CO2
Did you notice a difference in the rate of respiration between the sugars? Did any of the artificial sugars provide a good starting material for fermentation? Yes no artificial sugar did not provide a good starting material for fermentation as there was no change in height of gas.
Which tubes displayed evidence of anaerobic fermentation? How did you know? Due to change in gas height we can determine fermentation was occurring during to production of CO2
Hypothesize why some of the solutions were not metabolized. Research their chemical formulas.
How do the results of this experiment related to the role yeast play in baking?
Experiment 2Aerobic Respiration in Beans
How did the color of the bromothymol blue solution in each beaker change over time in each condition?
What is the mechanism driving the bromothymol blue solution color change?
What can be inferred from the color change of the bromothymol blue solution?
What evidence do you have that cellular respiration occurred in the beans? Explain your answer.
What are the controls in this experiment, and what variables do they eliminate?
If this experiment were conducted at 0 °C, what difference would you see in the rate of respiration? Why?
| Table 2: Bromothymol Blue Color Change Over Time for Pinto Bean Trial | |||
| Time | Pre-Soaked Pinto Beans | Dry Pinto Beans | No Pinto Beans |
| 0 min | |||
| 30 min | |||
| 60 min | |||
| 90 min | |||
| 120 min | |||
| 150 min | |||
| 180 min | |||
| 24 hours | |||
| Table 3: Bromothymol Blue Color Change Over Time for Kidney Bean Trial | |||
| Time | Pre-Soaked Kidney Beans | Dry Kidney Beans | No Kidney Beans |
| 0 min | |||
| 30 min | |||
| 60 min | |||
| 90 min | |||
| 120 min | |||
| 150 min | |||
| 180 min | |||
| 24 hours | |||
Photosynthesis Lab Report
- Plant Structure and Function
- Through the process called __________ plants convert lightenergy into
__________ energy. Record your answerbelow.
- In which structure of the plant does photosynthesis occur?
- What is the difference between xylem and phloem?
- Based on lab, Exercise 1, what is the name and function of thestructure labeled with the letter âHâ?
- Chloroplast
- Based on Lab, Exercise 2, draw and label each part of thechloroplast. Sign, date and prepare an image of your drawing andinclude it with this lab report.
- What part of the process of photosynthesis occurs in thethylakoid compartment?
- What is the name and function of the structure labeled with theletter âEâ in Exercise 2?
- Photosynthetic Products
- What are the three products of photosynthesis?
- What happens to the glucose that is not metabolizedimmediately?
- In the test for starch, which tube demonstrated a positive testfor starch? How do you know?
- Based on Lab, Exercise 3 explain why part of the leaf was amberin color.
- Light Absorption
- What pigment is used by plants to absorb light?
- In the video demonstration in Exercise 4 what happens to thelight spectrum when a green filter is placed in front of the lightsource?
- In step 3 of Exercise 4, which color was not absorbed by thespinach pigments?
- Photosynthetic Pigments
- What process is used in Exercise 5 to separate the plantpigments?
- Look at the chromatogram results in Exercise 5. What color isreflected by chlorophyll a?
- Which pigment reflected an orange color?
VI. Effect of Light and Temperature onPhotosynthesis
- What was the conclusion of Blackmanâs first experiment on theeffect of light on photosynthesis?
- In his second experiment, what effect did increasingtemperature have on the rate of photosynthesis?
- Record the data from Exercise 6 below.
Lamp Distance | Temperature | Ave Bubble/min |
75 cm | ||
50 cm | ||
25 cm |
- In the experiment in Exercise 6, what conclusion can be drawnabout the effect of light and temperature on rate ofphotosynthesis?
Summary Questions
- Why do heterotrophs depend on autotrophs?
- Name two reactants necessary for photosynthesis to occur.
- How would the process of photosynthesis be affected if a planthad no stomata?
- What tool is used to separate white light into differentwavelengths of color?
- Explain why we see the color green on the leaves ofplants.
- What color is absorbed the least by the petals on asunflower?
- Photosynthesis consists of two phases. Which phase would beleast affected by living in an area where there are shorter daysand long periods of darkness?
- How could air pollution affect food production and the priceyou pay for food at the supermarket?
