YEAST CELLS Biology 28/3 /2023 Cells must be able to do work and so must have energy available (both readily available and stored for future use.) ATP is perfectly designed to release just the right amount of energy needed for cellular work. Glucoseis perfectly designed for storing and transporting large quantities of energy to cells. Yeast is a living organism. It is Fungi. It is Unicellular. All of its activity happens in one cell. Respiration takes place when it is added to sugar. Sugar, Glucose, is changed in the cell to ATP (Energy) and the gas Carbon Dioxide. Oxygen is present. Fermentation is the extraction of energy from carbohydrates in the absence of oxygen. When yeast is added to grape juice to make wine. There are some substances that yeast like and some that kill them. Let’s look at Salt. Lab 1. Do Yeast Like Salt? Follow the lab Yeast and Salt. Fill in your hypothesis before you start. Fill in the data and write a summary Lab 2. Cellular Respiration and Fermentation in Yeast Purpose: To observe cellular respiration and fermentation in yeast/ Hypothesis: Write a hypothesis stating that all will produce the same amount of Carbon Dioxide or if you think it will differ, put in order the number of the test tube from the one that will produce the most Carbon Dioxide to the least: ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Procedure Set up the lab. We will use 6 test tubes. Label them. 1. Yeast and water 2. Yeast, water and sugar 3. Yeast and warm apple juice 4. Yeast and warm grape juice 5. Yeast and diet pepsi 6. Yeast and regular pepsi Blow up 6 balloons once to give it a good stretch. Each should be blown the same. Using a funnel add the 30 ml liquid and other substances to the test tube. Using a funnel add the yeast to the test tube 1 teaspoon each test tube. As soon as you add the materials, place a balloon on the test tube and add a rubber band to make sure it stays. Watch for 30 - 60 minutes. You could check the circumference of the balloons at 30 minutes, 1 hour, 4 hours, 8 hours and 12 hours and 24 hours after starting. Then we could look at the data on Friday. Balloon 1 2 3 4 5 6 30 min 60 min 4 hrs 8 hrs 12 hrs (no) 24 hrs X axis time Y axis Circumference Conclusions: Summarize your observations and include the answers to the following questions in your conclusions. This will take a couple paragraphs.1 1. Which balloon had the largest circumference? Why do you think that balloon had the largest circumference? 2. What caused the balloon(s) to expand? Where did this come from? 3. How did your results compare to your predictions? 4. What two things did the yeast need for cellular respiration? Where did they come from in each bottle? 5. What process did you stop when you closed the bottle by placing the balloon on top? 6. What did the yeast need to respire anaerobically? 7. What are some possible sources of error in your experiment? CONCLUSION:
