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

Cellular Respiration:  More Fun with Crayons

General Directions:  Use the diagram of cellular respiration (available on line) to answer the following questions.

1.  Four major reactions occur in the mitochondrion � pyruvate oxidation, TCA cycle, electron transport chain (ETC), oxidative phosphorylation.  Label each.

2. During pyruvate oxidation, which of the following occurs (circle all of the following that apply and then write the appropriate words next to the reaction):
        a. substrate level phosphorylation                    e. redox reaction
        b. oxidative phosphorylation                            f. dehydrogenase reaction
        c. decarboxyulation                                         g. oxidation/reduction reaction
        d. kinase reaction

3.  Explain the origin of the three names - tricarboxylic acid, Kreb�s, citric acid � for the biochemical cycle that occurs in the mitochondrion matrix.

4.  Locate the redox reactions that occur during the TCA cycle (hint: there are four).  Circle these and write �redox rxn� next to each.  What is the general name for the enzyme that catalyzes this type of reaction?

5.  How many of the reactions in the Kreb�s cycle involve NAD?  ________  How many of these reactions involve FAD? ____

6.  Locate the reactions in the citric acid cycle in which carbon dioxide is lost (hint:  there are three).  Write �decarboxylation� next to these reactions. 

7.  Locate a substrate level phosphorylation reaction in the TCA cycle.  Label it.

8.  Color in each of the four different complexes of protein/electron carriers in the ETC.

9.  What is final (terminal) acceptor of electrons in the ETC? _______  When this acceptor grabs electrons it becomes (oxidized / reduced) to ___________.

10.  During electron transport (circle the correct response):
  a.  electrons are moved from the matrix to the intermembrane space
  b.  electrons are moved from the intermembrane space to the matrix
  c.  protons are moved from the matrix to the intermembrane space
  d.  electrons are moved from the intermembrane space to the matrix. 

11.  Write �pH 5� and �pH 7� in the appropriate regions of the mitochondrion.

12. Locate and color the ATPase coupling factor that produces most of the ATP in the mitochondrion.

13.  The coupling factor is a (transmembrane protein, intergral protein, peripheral protein, glycocalyx carbohydrate, phospholipid).

14.  During the ETC
        a.  NADH is reduced to NAD+          c.  NADH is oxidized to NAD+
        b.  NAD+ is oxidized to NADH         d.  NAD+ is reduced to NADH 

15.  Explain why the oxidation of NADH yields more ATP than the oxidation of FADH2.

16.  Recall the summary equation for cellular respiration:  glucose + O2 carbon dioxide + water.  Locate the areas where each of the starting materials and end products are used/produced.

17.  Acetyl Coenzyme A, abbreviated CoA, is a �carrier� molecule that shuttles around small carbon fragments.  Find two reactions in which it is involved.

18.  What is the main function of the ETC?

19.  There are three major regions within a mitochondrion � matrix, inner membrane and intermembrane space.  Explain why.  Hint:  relate to the reactions that occur during each.

20.  Approximately how many different enzymes are required in the TCA cycle?  How do you know?

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