Photosynthesis Lessons

Introduction

These lessons use a web site developed by the Arizona State University Photosynthesis Center. You will be conducting a "virtual experiment" to study the role of different proteins that make up the photosynthetic apparatus of bacteria. There are three lessons in this exercise plus additional reading assignments.

Select your lesson from the links in the Table of Contents.

Lesson One:, Genetic Analysis of Photosynthetic Bacteria.
Lesson Two: Analysis of the Light Harvesting Genes.
Lesson Three: Summing Up the Experiment.
Lesson Four, Reading Assignments.
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Lesson One, Genetic Analysis if Photosynthetic Bacteria.

These are the questions you should answer for this first lesson. Read them before you start so you will have an idea of what information to look for as you work. You might want to print out this page of questions to have them on hand as you do the experiment. Take notes as you work and write the answers to the questions on the "Answer Form". At the end of the list of questions click on the link labeled "Start Lesson One" to begin.

Opening page. Use the links on the opening page labeled "bacteria" and "mutants" to learn more about these terms. You will need this information for the remainder of the lesson. Click on the "Sure Thing" link to continue.
Second page. This page describes the two-part hypothesis of bacterial photosynthesis. What are the two major parts of the system? Predict which of the two parts is most important. That is, if a mutant disabled one of the two parts of the system, which mutation would reduce the ability of the bacteria to produce sugar? Click on "Continue" to go to the next page.
Third page. What are the three mutations used in this experiment? What does it mean to be a "wild type" bacteria? Click on "Continue" to go to the next page.
Fourth page. Why did the scientists include the LH1+ LH2+ RC+ bacteria in this experiment? Use the links to "high light" and "low light" to learn more about the experimental conditions. Which light condition is more natural for these bacteria? Finally, you will need to answer the question on the page correctly before moving to the next page.
Fifth page. Click on "continue" to get to this page. Describe the color of the "wild type" cultures of bacteria under low and high light conditions. Answer the question on the page correctly to continue.
Sixth page. Describe the color of the LH1- mutation grown in high light conditions.
Last pages. Describe the LH2- and RC- mutants and continue to the page that asks you to suggest which mutant will have the greatest effect on photosynthesis. The correct answer takes you to the next page. Describe how do these mutants fit in with the two-part model of photosynthesis described at the beginning of the lesson. Write this answer on your answer sheet. Click on "Done" to finish this part of the exercise. Return to the Science home page for the second lesson.

Click here to Start Lesson One
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Lesson Two, Analysis of the Light Harvesting Genes .

In the first lesson you got some basic information about the relationships between the light harvesting genes (or the funnel proteins) and the reaction center (sugar producing mechanism). In this second lesson you will explore the relationship between the two mutations that affect the funnel proteins, LH1 and LH2. This is a list of the questions you will need to answer for this lesson. Print them out if you haven't done so already. Click on the "Start Lesson Two" link at the end of the list to begin. You will need to move from one page to the next the same way you did in the first lesson.

What differences do you observe between the control groups grown in low and high light conditions?
What differences do you observe between the RC- mutations grown in low and high light conditions?
What differences do you observe between the LH1- and LH2- mutations grown in high light conditions?
How would you describe the overall effect of low versus high light conditions on the rate of photosynthesis?
How are the two light harvesting genes, LH1 and LH2, related to the two-part model of photosynthesis outlined in lesson one? Be specific. Click on "Done" to finish this part of the exercise. Return to the Science home page for the third lesson.

Click here to Start Lesson Two.
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Lesson Three, Summing Up the Experiment.

In this third lesson you will use the information you learned in the previous ones to put relate the mutations to the two-part model of photosynthesis in bacteria. This is a list of the questions you will need to answer for this lesson. Print them out if you haven't done so already. Click on the "Start Lesson Three" link at the end of the list to begin. You will need to move from one page to the next the same way you did in the first two lessons.

You will be given three hypotheses to explain the relationships of the two LH proteins to one another. Write your answer on the "Answer Form" when you are done with this lesson Be sure to explain why you selected your answer.
On another page you will be asked to relate the two LH proteins to the reaction center proteins, RC. Again write your answer on the answer form and explain your choice. When you are done, click on the "Finished" link or go back to the Science Department home page.

Click here to Start Lesson Three.