Procedures
Instructions
Respiration in Yeast
Purpose: To design an experimental setup that will allow your group to produce the highest level of cellular respiration in the lab. Once the lab has been completed, you will then write a lab paper to describe your results.
Introduction
Yeasts are single cell fungi. In this activity you will investigate the type of yeast that people use to make bread, wine and beer. If you want to make bread, you can buy packets of little brown grains of yeast in the grocery store. These little brown grains may not seem to be alive, but if you put them in water with sugar, yeast grains will take up the sugar and use the energy stored in the sugar molecules to make ATP, which the yeast cells will use to carry out the processes of life.
During alcoholic fermentation in yeast cells:
· The sugar glucose is broken down to smaller molecules. Specifically, glucose (C6H12O6) is broken down to the alcohol ethanol (C2H6O) and carbon dioxide (CO2).
· As a glucose molecule is broken down, some of the energy stored in the chemical bonds of glucose is transferred to energy stored in the chemical bonds of ATP molecules.
Purpose: To design an experimental setup that will allow your group to produce the highest level of cellular respiration in the lab. Once the lab has been completed, you will then write a lab paper to describe your results.
Introduction
Yeasts are single cell fungi. In this activity you will investigate the type of yeast that people use to make bread, wine and beer. If you want to make bread, you can buy packets of little brown grains of yeast in the grocery store. These little brown grains may not seem to be alive, but if you put them in water with sugar, yeast grains will take up the sugar and use the energy stored in the sugar molecules to make ATP, which the yeast cells will use to carry out the processes of life.
During alcoholic fermentation in yeast cells:
· The sugar glucose is broken down to smaller molecules. Specifically, glucose (C6H12O6) is broken down to the alcohol ethanol (C2H6O) and carbon dioxide (CO2).
· As a glucose molecule is broken down, some of the energy stored in the chemical bonds of glucose is transferred to energy stored in the chemical bonds of ATP molecules.
There are several types of cellular respiration, anaerobic respiration (which also includes alcoholic fermentation and lactic acid fermentation) and aerobic respiration. What is the type of respiration that is occurring in the reaction above? How can you tell what type of respiration is occurring?
Testing for Respiration in Yeast Cells
One way to test for respiration in yeast cells is to evaluate whether CO2 is produced by yeast cells in water with sugar vs. water without sugar. If yeast cells carry out alcoholic fermentation, would you expect CO2 to be produced by:
· yeast cells in sugar water?
· yeast cells in plain water (without sugar)?
Explain your reasoning.
CO2 can also be produced by a simple chemical reaction without any living cells or enzymes and without producing ATP. For example, baking soda reacts with vinegar to produce CO2. This raises the possibility that dead yeast cells in sugar water produce CO2 as a result of a simple chemical reaction without carrying out alcoholic fermentation. To evaluate this possibility, you will test for CO2 production by dead yeast cells that have been boiled so the enzymes needed for alcoholic fermentation have been denatured and cannot catalyze the chemical reactions required for alcoholic fermentation.
Can dead yeast cells that were boiled carry out alcoholic fermentation of sugar to produce CO2? Explain your answer.
Experimental Design
Using your knowledge of cellular respiration, you will design an experiment to test cellular respiration in yeast cells. Your goal is to be the group that has the highest level of cellular respiration of everyone in the class. How will you do this?
You will design the experiment step by step for this lab by the end of the week. You will need to create each and every step that you will follow. Below are some hints in writing an experimental procedure.
1. Be specific.
2. List your steps.
3. Think about the order (do you fill it up with water first, and then add yeast, or the other way around?)
4. How are you going to see your results?
5. What is your control?
6. What are the things that you are changing to hopefully see results?
7. What supplies are you going to need?
8. How many different set-ups will be enough? How many will be too many?
9. Sometimes simpler is better.
If you are stuck, you may ask for help, but you are being given as much freedom as possible to do anything you think will help you be the most successful. You may refer to Blackawton Bees (materials and methods section) to see an article that was written by first graders to give you an idea as to what your procedure could look like. Mr. U must approve your procedure before you can do the lab.
One suggestion, to get you started is the set up below to possibly measure respiration:
Testing for Respiration in Yeast Cells
One way to test for respiration in yeast cells is to evaluate whether CO2 is produced by yeast cells in water with sugar vs. water without sugar. If yeast cells carry out alcoholic fermentation, would you expect CO2 to be produced by:
· yeast cells in sugar water?
· yeast cells in plain water (without sugar)?
Explain your reasoning.
CO2 can also be produced by a simple chemical reaction without any living cells or enzymes and without producing ATP. For example, baking soda reacts with vinegar to produce CO2. This raises the possibility that dead yeast cells in sugar water produce CO2 as a result of a simple chemical reaction without carrying out alcoholic fermentation. To evaluate this possibility, you will test for CO2 production by dead yeast cells that have been boiled so the enzymes needed for alcoholic fermentation have been denatured and cannot catalyze the chemical reactions required for alcoholic fermentation.
Can dead yeast cells that were boiled carry out alcoholic fermentation of sugar to produce CO2? Explain your answer.
Experimental Design
Using your knowledge of cellular respiration, you will design an experiment to test cellular respiration in yeast cells. Your goal is to be the group that has the highest level of cellular respiration of everyone in the class. How will you do this?
You will design the experiment step by step for this lab by the end of the week. You will need to create each and every step that you will follow. Below are some hints in writing an experimental procedure.
1. Be specific.
2. List your steps.
3. Think about the order (do you fill it up with water first, and then add yeast, or the other way around?)
4. How are you going to see your results?
5. What is your control?
6. What are the things that you are changing to hopefully see results?
7. What supplies are you going to need?
8. How many different set-ups will be enough? How many will be too many?
9. Sometimes simpler is better.
If you are stuck, you may ask for help, but you are being given as much freedom as possible to do anything you think will help you be the most successful. You may refer to Blackawton Bees (materials and methods section) to see an article that was written by first graders to give you an idea as to what your procedure could look like. Mr. U must approve your procedure before you can do the lab.
One suggestion, to get you started is the set up below to possibly measure respiration: