Loading...

BIO101A: Introduction to Molecular and Cellular Biology

Unit 4: Photosynthesis  

Photosynthesis is the ultimate source of energy for every living being on earth, whether directly or indirectly. In middle school, you probably learned about photosynthesis as a single reaction. You will now learn that photosynthesis is actually a series of several different reactions that convert carbon dioxide and water into glucose. BIO306: Botany goes into this subject in more detail.

Unit 4 Time Advisory
Completing this unit should take you approximately 13.5 hours. 

☐   Unit 4: 3 hours

☐   Subunit 4.1: 1.5 hours
 
☐   Subunit 4.2: 2 hours
 
☐   Subunit 4.3: 0.5 hours
 
☐   Subunit 4.4: 2.5 hours
 
☐   Subunit 4.5: 0.5 hours
 
☐   Subunit 4.6: 0.5 hours

☐   Subunit 4.7: 2.5 hours
 
☐   Assessment: 0.5 hours

Unit4 Learning Outcomes
Upon successful completion of this unit, you will be able to:
- provide an overview of the reactions in photosynthesis;  -  explain how light energy is harnessed by photosynthesis to fix CO2 into sugars;  -  list the inputs and outputs of photosynthesis;  -  list the places where high-energy molecules are produced in the chloroplast; and  -  describe how light reactions, the Calvin cycle, and ATP synthase interact or are interconnected. 

4.1 Reactants and Products   - Reading: University of California, Davis: ChemWiki: “Photosynthesis Overview”

Link: University of California, Davis: *ChemWiki*: [“Photosynthesis
Overview”](http://chemwiki.ucdavis.edu/Biological_Chemistry/Photosynthesis/Photosynthesis_overview) (HTML)


 Instructions: Read this article and click on the embedded links to
gain an understanding of the overall reaction.  

 Reading this article and taking notes should take approximately 1
hour and 30 minutes.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0 United States
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/). It
is attributed to the University of California, Davis.

4.2 Light-Dependent Reaction and Noncyclic Photophosphorylation   - Reading: University of California, Davis: ChemWiki: “The Light Reactions”

Link: University of California, Davis: *ChemWiki*: [“The Light
Reactions”](http://chemwiki.ucdavis.edu/Biological_Chemistry/Photosynthesis/Photosynthesis_overview/The_Light_Reactions) (HTML)  

 Instructions: Read this article to understand the first stage of
photosynthesis: photon capture.  

 Reading this article and taking notes should take approximately 1
hour.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0 United States
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/). It
is attributed to the University of California, Davis.

4.3 Cyclic Photophosphorylation   - Reading: Estrella Mountain Community College: Michael J. Farabee’s “Photosynthesis”

Link: Estrella Mountain Community College: Michael J.
Farabee’s [“Photosynthesis”](http://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPS.html) (HTML)  
  

Instructions: Read the “Light Reactions” section to understand how
ATP is generated. The noncyclic photophosphorylation is the normal
route by which the Calvin cycle obtains the high-energy molecules,
ATP and NADPH, produced by the light reactions. However, the Calvin
cycle consumes more ATP than NADPH. Therefore, plants need to use
cyclic photophosphorylation, producing only ATP, to satisfy the
needs of the Calvin cycle.  

 Reading this section and taking notes should take approximately 30
minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

4.4 Calvin Cycle and Carbon Fixation   - Web Media: McGraw Hill: Online Learning Center: “How the Calvin Cycle Works”

Link: McGraw Hill: Online Learning Center: [“How the Calvin Cycle
Works”](http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html) (Flash)  

 Instructions: Go through this animation to learn about the Calvin
cycle, and then take the quiz below the animation to gauge how well
you have learned the material. The dark reactions or the Calvin
cycles use the high-energy molecules generated by the light
reactions to create bonds between carbon dioxide molecules to form
sugar molecules (i.e., carbon fixation). These sugar-creating
reactions are catalyzed by many enzymes, but the most important
carbon fixing enzyme is RuBisCO, which is the world’s most abundant
enzyme. Although the Calvin cycle is considered a light-independent
reaction, it cannot occur without light. We can call it
light-independent because, although it requires reactants produced
from light-dependent reactions, the reaction itself does not
directly involve light.  

 Watching this animation and answering the questions should take
approximately 30 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

4.4.1 RuBisCO   - Reading: Estrella Mountain Community College: Michael J. Farabee’s “Photosynthesis” Link: Estrella Mountain Community College: Michael J. Farabee’s “Photosynthesis” (HTML)

 Instructions: Read the “C-4 Pathway” section to understand the role
that the enzyme RuBP plays in the Calvin cycle.  

 Reading this section and taking notes should take approximately 15
minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

4.4.2 RuBP   - Reading: University of California, Davis: ChemWiki: “Ribulose-1,5-bisphosphate carboxylase (rubisco)”

Link: University of California, Davis: *ChemWiki*:
[“Ribulose-1,5-bisphosphate carboxylase
(rubisco)”](http://chemwiki.ucdavis.edu/index.php?title=Wikitexts/UC_Davis/UCD_Chem_124A:_Berben/Ribulose_1%2C5-bisphosphate_carboxylase_(rubisco)/Rubisco_1)
(HTML)  

 Instructions: Read this article to understand how RuBisCo is used
in the Calvin cycle for carbon fixation.  

 Reading this article and taking notes should take approximately 30
minutes.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0 United States
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/). It
is attributed to the University of California, Davis.

4.5 Chloroplasts and Thylakoids   - Reading: Estrella Mountain Community College: Michael J. Farabee’s “Photosynthesis”

Link: Estrella Mountain Community College: Michael J. Farabee’s
[“Photosynthesis”](http://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPS.html) (HTML)  

 Instructions: Read the “Structure of the Chloroplast and
Photosynthetic Membranes” and “Light Reactions” sections to learn
where photosynthesis occurs on chloroplasts.  

 Reading these sections and taking notes should take approximately
30 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

4.6 Chemiosmotic Theory   - Reading: University of California, Davis: ChemWiki: “Case Study: Thermodynamics of ATP”

Link: University of California, Davis: *ChemWiki*: [“Case Study:
Thermodynamics of
ATP”](http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/Case_Studies/Case_Study%3a_Thermodynamics_of_ATP?highlight=chemiosmosis) (HTML)  

 Instructions: Read this article to understand how ATP can be formed
through chemiosmosis.  

 Reading this article and taking notes should take approximately 30
minutes.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0 United States
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/). It
is attributed to the University of California, Davis.

4.7 Unit 4 Problem Set   - Assessment: The Saylor Foundation’s “BIO101 Unit 4 Problem Set” Link: The Saylor Foundation’s “BIO101 Unit 4 Problem Set” (PDF)

Instructions: Attempt this assessment to gauge your understanding of
the topics covered in this unit. Please note that you may have to
conduct independent research to understand some of the concepts in
this assessment, though these concepts are related to what you have
studied in this unit .You may check your answers against the [“Guide
to
Responding”](http://www.saylor.org/site/wp-content/uploads/2014/05/BIO101A-GuidetoProblemSet4-FINAL.pdf)
(PDF) when you have finished.  

 Completing this assessment should take approximately 30 minutes.

Unit 4 Quiz   - Assessment: The Saylor Foundation’s “BIO101 Unit 4 Quiz” Link: The Saylor Foundation’s “BIO101 Unit 4 Quiz” 

Instructions: Complete this assessment to gauge your understanding
of the topics covered in this unit. The correct answers will be
displayed when you click the “Submit” button.  

 Completing this assessment should take approximately 30 minutes.