Introduction to Cell & Molecular Biology (BIOL121) - Dr. S.G. Saupe (; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321

Study Guide & Review Sheet for Respiration

I. Goal:  Life can, in an abstract sense, be viewed as a sustained, integrated and complex series of chemical reactions. Our goal in this unit will be an understanding of the basic principles of chemical reactions and biological energetics that govern the major anabolic (photosynthesis) and catabolic (glycolysis, cellular respiration) reactions of living systems. Specifically, we will investigate glycolysis, fermentation and cellular respiration.

II. Learning Objectives: Upon completion of this unit you should be able to:

  1. describe ATP and explain why it is so vitally important for living things.
  2. describe the difference between a substrate level and oxidative phosphorylation.
  3. describe how most cellular ATP is made.
  4. describe and explain the major events occurring during glycolysis.
  5. describe the two major anaerobic pathways for pyruvic acid metabolism (i.e., fermentation).
  6. explain the significance/importance of glycolysis and fermentation.
  7. describe the structure of the mitochondrion.
  8. describe and explain the major events occurring during the Citric Acid Cycle and their significance.
  9. describe and explain the major events occurring during the electron transport chain and their significance.
  10. explain the chemi-osmotic hypothesis for ATP synthesis.
  11. summarize the energy yield from glucose during glycolysis, fermentation, and aerobic respiration.
  12. write and explain the general equation for glucose catabolism

III. Reading(s):

  • Textbook Chapter 9

IV. Learning Activitieshere are a few possible learning activities

  1. prepare written answers to the objectives
  2. write a dialog using as many of the terms in the chapter as possible
  3. prepare a concept map for this material
  4. answer the questions at the end of the chapter
  5. go through the CD-ROM that accompanies the text.
  6. Define the following terms:
aerobic respiration
anaerobic respiration
Citric Acid Cycle
kinetic energy
Kreb's Cycle
oxidative phosphorylation
potential energy
redox reaction
substrate level phosphorylation

V. Study Hints:

  1. Do not memorize the various pathways; strive to understand what is occurring during each.
  2. For each major pathway, know where it occurs, briefly what occurs and why it occurs. Also, know the starting materials and end products.
  3. Attempt to summarize each pathway in your own words.
  4. Be able to use conversationally, the terms/concepts listed above or in the textbook.
  5. Read the pertinent text chapter.
  6. Complete the pertinent sections in the study guide.
  7. Pretend you are a molecule of glucose. Follow it through all the pathways and describe what you encounter, where and why.
  8. Make a concept map for each of the major pathways.

 VI. Additional Hints: If I were to take one of my Concepts exams I would study as follows:

  1. Lecture Notes. I'd come to class and get a great set of lecture notes. Write everything down that's said by students, teacher or that you think about. You should be writing and thinking constantly. Write down questions or ideas as you go along.
  2. Web Notes. Get a copy of the notes as soon as they are available.
  3. Summary Notes. Now, create a summary set of notes by condensing important info from lecture, web and text. Read the pertinent sections in the text and record this information as well. This is now your working set of notes.
  4. Study Time. So far, you really haven't started to "study" - you have simply gathered information. Now, it's time to process the info. Begin to ask yourself the "w" questions - why, when, where, how, etc - for everything that appears in your notes. Can you explain this to someone else? Imagine you are going to teach someone else about this topic. Could you do it?
  5. Test time. Can you answer the questions in the study guide that comes with the text? in this study guide? in the CD-ROM. Quiz your friends. Talk biology with someone - call your family or friends and tell them about what you're learning. Talk biology with your profs. Go to the library and read additional books about the topic.

VII. Study Questions 

  1. Under what conditions does fermentation occur?
  2. There are two major types of fermentations that are characterized by their end products.  Identify these and the organisms in which they occur.
  3. Circle the redox reaction that occurs during each type of fermentation.  Indicate which components are oxidized and which are reduced.  What type of enzyme is responsible for this reaction?
  4. Note that ATP is not a direct product of the reactions of fermentation?  So, what is the purpose of fermentation?
  5. Locate the redox reactions that occur in the mitochondria (hint there are five).  Write redox reaction next to each.
  6. Locate the reactions in which carbon dioxide is lost (hint there are three).
  7. Locate a substrate level phosphorylation reaction in the mitochondrion.  Label it.
  8. Acetyl coenzyme A can be considered a �carrier� molecule.  Find two reactions in which it is involved.
  9. When pyruvic acid enters the mitochondrion it gets oxidized and converted to acetyl coenzyme A and carbon dioxide by a large enzyme complex in the inner mitochondrial membrane.  Locate this reaction and label it �Pyruvate oxidation complex.�
  10. Locate the electron transport chain.  Label I �NADH-Q reductase complex;� label III �Cytochrome c reductase complex;� label IV �cytochrome c oxidase complex;� and label II �Succinate-Q reductase complex.�  Label Q � �Ubiquinone.�
  11. Write pH 5 and pH 7 in the appropriate regions in the mitochondrion.
  12. Locate and color the Fo/F1 Coupling Factor ATPase that produces most of the ATP in the mitochondrion.
  13. Explain why the oxidation of each NADH yields 3 ATP but the oxidation of each FADH2 only yields two.
  14. Recall the summary equation for respiration:  glucose + O2   CO2  + H2O.  Find the areas where these materials are used/produced.


  1. Which of the following does not occur in the Kreb's Cycle? (moderately difficult)
    a. redox reactions
    b. production of NADH
    c. production of FAD+
    d. production of carbon dioxide
    e. synthesis of ATP
  1. Glycolysis occurs in the: (simple)
    a. cytoplasm
    b. matrix
    c. chloroplast
    d. mitochondria
    e. grana
  1. The reason that organisms ferment pyruvic acid is to: (moderately difficult)
    a. regenerate oxidized coenzymes
    b. produce lactic acid
    c. produce ethanol
    d. produce ADP
    e. recycle carbon dioxide

Some Additinal Questions:

1. For each of the following, name the reaction(s) that occurs in that structure:

  1. matrix
  2. cristae
  3. cytoplasm.

2. Consider a yeast cell that is fed glucose in which all the carbon atoms are radioactively labeled with carbon-14. Answer the following true or false. Then, correct any false statements:

  1. Under aerobic conditions, radioactivity would be found in water, ATP, and carbon dioxide
  2. Under anaerobic conditions, radioactivity would be found in carbon dioxide and lactic acid
  3. NAD would become labeled under aerobic or anaerobic conditions.

3. We discussed allosteric regulation in a previous class. Explain the advantage to the cell for each of the following regulatory mechanisms: (a) Isocitrate dehydrogenase is allosterically activated by ADP; and (b) phosphofructokinase is allosterically inhibited by citrate.

4. Cyanide is a potent inhibitor of the electron transport chain. Specifically, cyanide blocks the cytochrome a-a3 complex from reducing oxygen. Which of the following is true concerning a cell treated with cyanide? (can you correct the false statements?):

  1. cells use more oxygen
  2. NADH accumulates in the cell
  3. the rate of electron flow in the chain increases
  4. glycolysis will stop

Though Questions
: (these questions were 'borrowed' from a cell biology text whose author I have forgotten - sorry)

1.  Normally, oxidative phosphorylation is tightly coupled to electron transport. Or in other words, no electron flow through the ETC will occur unless ATP can be made. However, there are certain uncoupling agents that allow electron flow while preventing ATP synthesis. One such agent is 2,4-dinitrophenol (DNP) which is toxic to humans causing a marked increase in metabolism and temperature, sweating, collapse and death. For a brief period in the 1940�s, sublethal doses of DNP were actually prescribed as a means of weight reduction in humans.

    1. Why would an uncoupling agent like DNP be expected to cause an increase in metabolism, as evidenced by consumption of oxygen or catabolism of food?
    2. Why would consumption of DNP lead to an increase in temperature and to profuse sweating?
    3. DNP has been shown to carry protons across membranes. How might this observation be used to explain its uncoupling effect?
    4. Why would DNP have been considered a drug for weight reduction? Can you guess why it was abandoned as a reducing aid?

2.  Recall that in the enzyme unit we mentioned that elevated levels of lactate dehydrogenase (LDH) in the blood is an indication of a heart attack. Knowing that LDH catalyzes the reduction of pyruvate to lactate in an anaerobic environment, explain why might there be a relationship between a heart attack and this enzyme.

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Last updated: July 14, 2009     � Copyright by SG Saupe