Only need Part B to be completed. Thank you
Biology 160 Lab Module 6 Respiration and Fermentation IntroductionThis week, we will be exploring how cellular respiration and fermentation work. We will do a simple experiment on fermentation at home using yeast, Saccharomyces cerevisiae.
Cellular Respiration is the main pathway for production of energy in aerobic (oxygen requiring) organisms. In cellular respiration, glucose is broken down in stages and the energy is harvested in the form of electrons. Those electrons are used to make ATP in a process called Oxidative Phosphorylation. This process consumes Oxygen and Carbon Dioxide is produced. In part A you will work through some problems exploring how this process works.
Fermentation is a form of energy metabolism that is important in the production of many foods and beverages including cheeses, yogurt, sauerkraut, beer and other alcoholic beverages, and even things like chocolate and coffee. Many organisms are capable of performing fermentation. Their by-products vary, depending on the organic molecule that is fermented and the enzyme system that the organism uses. In all cases, fermentation involves the breakdown of pyruvate and the oxidation of NADH to NAD+. Human muscle cells, for example, convert pyruvate to lactate (lactic acid), as shown in the figure to the left (Figure 4.16 from Concepts Biology). When Saccharomyces cerevisiae performs fermentation, ethanol and carbon dioxide (CO2) are produced.
Learning OutcomesUpon successful completion of this lab, you should be able to demonstrate:
Explain how Cellular Respiration produces energy in the presence of Oxygen
Explain the purpose and process of Fermentation when oxygen is not available.
Set up an document a simple experiment on Fermentation
Concepts of Biology (our textbook): Section 4.2 Glycolysis (pg 108-110)
Concepts of Biology (our textbook): Section 4.3 Citric Acid Cycle (110-111)
Concepts of Biology (our textbook): Section 4.4 Oxidative Phosphorylation (111-113)
Concepts of Biology (our textbook): Section 4.5 Fermentation (114-117)
Video overview of Cellular Respiration: LINK
Video overview of Fermentation: LINK
Optional: A biologist’s ode to Saccharomyces cerevisiae (note: it’s a song about beer): LINK
Part A: Cellular Respiration Questions
What is the equation for glycolysis?
What is the overall chemical equation for aerobic respiration? (From pyruvate)
Cellular respiration has three stages:
Transformation of pyruvate to acetylCoA
The citric acid cycle (Krebs cycle) completes the breakdown of glucose
Oxidative phosphorylation accounts for most of the ATP synthesis
Why is glycolysis NOT a true step of aerobic respiration even though it comes before?
Why might we call it pre-Stage 1?
How much ATP is made per molecule of glucose in an organism using aerobic respiration?
See if you can label the stages cellular respiration correctly.
If Glycolysis is pre-stage 1, where/what is stage 1? Label it on the diagram. (You can use text boxes)
Figure A: Lactic Acid Fermentation
Figure B: Alcoholic Fermentation
QuestionsLook carefully at both forms of fermentation. Our muscles do lactic acid fermentation. Yeast does Alcohol fermentation.
What is the key molecule that BOTH processes are producing?
Why would we need to produce that molecule even if it means wasting the energy in pyruvate?
Why do we only need to use fermentation if Oxygen is not present?
What does it mean to be a co-enzyme, and why is this molecule a co-enzyme for glycolysis?
Look carefully at both forms of fermentation again.
What is the end product for alcohol fermentation?
What by product does alcohol fermentation produce?
Why can we use this molecule to measure fermentation in water? [Hint: review the combination of water and carbon dioxide in Chapter 2.]
What are the overall chemical equations for human muscle fermentation and for yeast fermentation? (from pyruvate)
Compare/contrast fermentation & anaerobic respiration? How are they the same? How are they different?
Compare/contrast anaerobic and aerobic respiration? How are they the same? How are they different?
Why do all of these processes need an electron acceptor?
How much ATP is made per molecule of glucose in an organism using fermentation?
How much potential ATP is being wasted in the pyruvate? Remember there are 2 pyruvate created per glucose molecule.
Why is aerobic respiration efficient?
Part C: Fermentation in Action
This portion of that lab will be based entirely on the materials you have on hand. You will need:
A sugar source
A yeast source
A vessel to safely contain your experiment
A plan to get some qualitative data
A camera to document what you made
We are going to ferment some food items in your kitchen. Nothing used here will be unsafe to handle and may even make a tasty consumable when you are done. The goal is for you to observe fermentation in action. I am going to present you with options for fermentation activities. Choose ONE to record, but feel free to play with others if they appeal.
To complete this activity, if possible, make one of the four recipes below (substitutions, failures and experimentation is ENCOURAGED). Document your process below:
Choose one of the four options below. The materials list will give you a general idea of what you need to choose the option. The goal is that you shouldn’t have to go out or get anything for at least ONE of these options. If you do not have access to the necessary supplies for any of the first four options, then perform Option 5.
Option 1: Make your own sodaMaterials List:
Bakers yeast
Table sugar (honey, maple syrup or corn syrup will work)
Flavoring (recipe I provide will use ginger and lemon)
2L SODA bottle (MUST be a bottle that can take a little pressure NOT a glass bottle)
Here is the link to an easy recipe for Ginger ale: LINK
Another soda recipe is provided in Appendix A (at the end of this lab handout)
Option 2: Homemade Fast BreadMaterials List:
Bakers yeast
Table sugar (honey, maple syrup or corn syrup will work)
Salt
Flour
Water
Here is the link to an easy recipe for Fast Bread: LINK
*If you don’t have flour but do have yeast and sugar, you can do just the first part of this recipe and observe the yeast mixture to complete your lab.
Option 3: Make your own sourdough starterMaterials List:
Flour (can try this with ANY type of flour)
Water
Helpful things to have: Rye or Whole Wheat flour, raisins or other dried fruit, a whole apple (or pear), grapes, whole unmilled grain (brown rice, barley, etc)
Here is a link to an easy method for starting a sourdough starter: LINK
Option 4: Homemade yogurtMaterials List:
Milk (can try with milk alternates, soy and coconut should work)
Commercial yogurt, buttermilk or sourcream (can try any that says ‘live culture’ on it)
Here is a link to an easy yogurt recipe: LINK
Option 5: No kitchen required (if you do not have supplies for Options 1-4)Materials List:
Internet access
Complete this tutorial and answer the questions below: LINK
Part C Report Sheet:I chose to follow option: _____________
Describe what your culture looked like when you set it up? Include a photo. (If you do not embed the photo here, please LABEL it with your name and which question you are answering!)
Did fermentation take place in your culture?
How could you tell? (note what you observed, sight, smell, feel or other things you noticed)
What was produced by your sample that you were able to observe?
Which type of fermentation did your sample do? Alcoholic or Lactic Acid? How do you know?
Include a picture of your culture AFTER fermentation that shows what you observed above. (If you do not embed the photo here, please LABEL it with your name and which question you are answering!)
What organisms do you think are responsible for the fermentation you observed (or tried to observe!) *You may need to do some searching to answer this.
What was your sugar source in this experiment. NAME your sugar using terminology from Chapter 2.
What happened to the sugar in your experiment? Where did the Carbon from your sugar molecules end up? (Hint: look at 3c above!)
What would happen if you change the pH of your sample by adding acid or base to it? Why? (Hint: think about the enzyme lab we completed previously!)
Materials List:
Bakers yeast
Table sugar (honey, maple syrup or corn syrup will work)
Flavoring (recipe I provide will use ginger and lemon)
2L SODA bottle (MUST be a bottle that can take a little pressure NOT a glass bottle)
Here is the link to an easy recipe for Ginger Ale: LINK
If you choose this option, the above link is REQUIRED reading. **Homemade soda is an AGGRESSIVE fermenter, it can explode bottles. Exploding plastic bottles are messy, exploding glass bottles are DANGEROUS**
Here is the general idea, and method to PLAY with recipe. To make this work you need sugar and yeast. If you do not have yeast at home, choose a different option.
Base Recipe for Soda:Sugar: Minimum ¼ cup (try subbing honey, maple syrup or corn syrup)
Baker’s Yeast (any type): ¼ tsp (cannot substitute this if you don’t have yeast, pick a different option!)
Water: Tap water is fine enough to fill your bottle
Flavoring: You can use what you like, my recipe uses grated ginger, try using orange or lemon juice, a flavor extract or some fruit pulp that you like.
Bring 2 cups of water to a boil and dissolve your sugar in the water. If you are using a fruit or ginger flavor, mix it in here. Let this mix cool to room temperature and strain out the fruit/ginger bits.
In your clean 2L bottle add ¼tsp of yeast and your cooled syrup. Fill the bottle as shown in the link above, cap the bottle and shake to mix in the yeast and syrup. Let the bottle sit at room temperature for 12-24 hours and periodically give it a squeeze. When you feel pressure in the bottle, gently open the lid to vent the gas. Then refrigerate the bottle. You can now drink your soda. Keep it in the fridge and open the lid every day (it can explode if you forget to vent it!).
**This will contain a tiny amount of alcohol, about 0.4% (beer is ~5%). If you are underage, get parental permission to make this first.
*If you do not have a 2L plastic bottle, you could make a ½ or even a ¼ batch and use smaller soda bottles. You can also do this in an OPEN jar or bottle (it will not get as carbonated, but will still work). DO NOT tightly cap a glass bottle for this recipe.