Chapter 6
Metabolism of Microorganisms
Chapter Summary and Essay Questions
The breakdown (catabolism) and synthesis (anabolism) of carbohydrates are the two major forms
of metabolism discussed in Chapter 6. Because these forms of metabolism involve enzymes and
energy, these latter topics are discussed first. Special attention is given to how energy is stored
and released for the chemistry of microbial life. When you have studied the chapter, you should
be able to answer the following essay questions:
a. Compare anabolism with catabolism and endergonic reactions with exergonic reactions.
b. Describe the chemical characteristics of enzymes, and indicate why they are important in the
metabolism of large organic molecules.
c. Discuss the significance of the enzyme-substrate complex, explaining how it affects the
activation energy of a reaction.
d. Compare cofactors and coenzymes.
e. Draw a metabolic pathway, showing how enzymes are used and feedback inhibition works.
f. Describe the chemical structure of ATP and the role of the ATP/ADP cycle in chemical
reactions in the cell.
g. Outline the major steps in glycolysis and show how two molecules of ATP are the net result
of this metabolic pathway.
h. Summarize what takes place in the citric acid cycle, and indicate what is gained from this
cyclic metabolic pathway.
i. Support the statement “The real importance of glycolysis and the citric acid cycle is the
generation of NADH and FADH2.”
j. Outline the process of oxidative phosphorylation, showing how 38 molecules of ATP can
result from the metabolism of a molecule of glucose.
k. Assess the role of cytochromes, ATP synthase, and oxygen gas to the aerobic respiration
process.
l. Describe how other carbohydrates, as well as proteins and fats, can be metabolized to yield
energy for cellular activities.
m. Distinguish between aerobic respiration and anaerobic respiration.
n. Explain the advantage afforded those microorganisms that can carry out fermentation using
yeasts and streptococci in your explanation.
o. Explain the process of photosynthesis as it takes place in cyanobacteria.
p. Distinguish between autotrophy and heterotrophy as patterns of metabolism.
q. Distinguish between the energy and carbon sources for the four nutritional classes of
microorganisms.