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Problem 2.4a
Classify the following types of chemical reactions.
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Problem 2.5a
Bacteria use the enzyme urease to obtain nitrogen in a form they can use from urea in the following reaction:
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What purpose does the enzyme serve in this reaction? What type of reaction is this?
Problem 2.5a
The best definition of ATP is that it is
a. a molecule stored for food use.
b. a molecule that supplies energy to do work.
c. a molecule stored for an energy reserve.
d. a molecule used as a source of phosphate.
Problem 2.7a
DRAW IT The artificial sweetener aspartame, or NutraSweet®, is made by joining aspartic acid to methylated phenylalanine, as shown in the following.
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a. What types of molecules are aspartic acid and phenylalanine?
b. What direction is the hydrolysis reaction (left to right or right to left)?
c. What direction is the dehydration synthesis reaction?
d. Circle the atoms involved in the formation of water.
e. Identify the peptide bond.
Problem 5.1a
Use the following diagrams (a), (b), and (c) for question 1.
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Name pathways diagrammed in parts (a), (b), and (c) of the figure.
a. Show where glycerol is catabolized and where fatty acids are catabolized.
b. Show where glutamic acid (an amino acid) is catabolized:
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c. Show how these pathways are related.
d. Where is ATP required in pathways (a) and (b)?
e. Where is CO₂ released in pathways (b) and (c)?
f. Show where a long-chain hydrocarbon such as petroleum is catabolized.
g. Where is NADH (or FADH₂ or NADPH) used and produced in these pathways?
h. Identify four places where anabolic and catabolic pathways are integrated.
Problem 5.10a
DRAW IT What nutritional type is a colorless microbe that uses the Calvin-Benson cycle, uses H₂ as the electron donor to its ETC, and uses elemental S as the final electron acceptor in the ETC?
Problem 5.1a
Which substance in the following reaction is being reduced?
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a. acetaldehyde
b. NADH
c. ethanol
d. NAD⁺
Problem 5.10a
Use the following choices to answer questions 7–10.
a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days
b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days
c. both a and b
d. neither a nor b
Which culture uses the most glucose?
Problem 5.2a
DRAW IT Using the following diagrams, show each of the following:
a. where the substrate will bind
b. where the competitive inhibitor will bind
c. where the noncompetitive inhibitor will bind
d. which of the four elements could be the inhibitor in feedback inhibition
e. What effect will the reactions in (a), (b), and (c) have?
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Problem 5.2a
Which of the following reactions produces the most molecules of ATP during aerobic metabolism?
a. glucose → glucose 6-phosphate
b. phosphoenolpyruvic acid → pyruvic acid
c. glucose → pyruvic acid
d. acetyl CoA → CO₂ + H₂O
e. succinic acid → fumaric acid
Problem 5.3a
DRAW IT An enzyme and substrate are combined. The rate of reaction begins as shown in the following graph. To complete the graph, show the effect of increasing substrate concentration on a constant enzyme concentration. Show the effect of increasing temperature.
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Problem 5.3a
Which of the following processes does not generate ATP?
a. photophosphorylation
b. the Calvin-Benson cycle
c. oxidative phosphorylation
d. substrate-level phosphorylation
e. All of the above generate ATP
Problem 5.4a
Which of the following compounds has the greatest amount of energy for a cell?
a. CO₂
b. ATP
c. glucose
d. O₂
e. lactic acid
Problem 5.4a
Define oxidation-reduction, and differentiate the following terms:
a. aerobic and anaerobic respiration
b. respiration and fermentation
c. cyclic and noncyclic photophosphorylation
Problem 5.5a
There are three mechanisms for the phosphorylation of ADP to produce ATP. Write the name of the mechanism that describes each of the reactions in the following table.
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Problem 5.5a
Which of the following is the best definition of the Krebs cycle?
a. the oxidation of pyruvic acid
b. the way cells produce CO₂
c. a series of chemical reactions in which NADH is produced from the oxidation of pyruvic acid
d. a method of producing ATP by phosphorylating ADP
e. a series of chemical reactions in which ATP is produced from the oxidation of pyruvic acid
Problem 5.6a
All of the energy-producing biochemical reactions that occur in cells, such as photophosphorylation and glycolysis, are ________ reactions.
Problem 5.6a
Which of the following is the best definition of cellular respiration?
a. a sequence of redox reactions with O₂ as the final electron acceptor
b. a sequence of redox reactions with the final electron acceptor from the environment
c. a method of generating ATP
d. the complete oxidation of glucose to CO₂ and H₂O
e. a series of reactions in which pyruvic acid is oxidized to CO₂ and H₂O
Problem 5.7a
Fill in the following table with the carbon source and energy source of each type of organism.
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Problem 5.7a
Use the following choices to answer questions 7–10.
a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days
b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days
c. both a and b
d. neither a nor b
Which culture produces the most lactic acid?
Problem 5.8a
Write your own definition of the chemiosmotic mechanism of ATP generation. On Figure 5.16, mark the following using the appropriate letter:
a. the acidic side of the membrane
b. the side with a positive electrical charge
c. potential energy
d. kinetic energy
Problem 5.8a
Use the following choices to answer questions 7–10.
a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days
b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days
c. both a and b
d. neither a nor b
Which culture produces the most ATP?
Problem 5.9a
Why must NADH be reoxidized? How does this happen in an organism that uses respiration? Fermentation?
Problem 5.9a
Use the following choices to answer questions 7–10.
a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days
b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days
c. both a and b
d. neither a nor b
Which culture uses NAD⁺ ?
Problem 6.10a
An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an
a. aerobe.
b. aerotolerant anaerobe.
c. obligate anaerobe.
Problem 6.3a
Define and explain the importance of each of the following:
a. catalase
b. hydrogen peroxide
c. peroxidase
d. superoxide radical
e. superoxide dismutase
Problem 8.3a
Feedback inhibition differs from repression because feedback inhibition
a. is less precise.
b. is slower acting.
c. stops the action of preexisting enzymes.
d. stops the synthesis of new enzymes.
e. all of the above
Problem 8.5a
Suppose you inoculate three flasks of minimal salts broth with E. coli. Flask A contains
glucose. Flask B contains glucose and lactose. Flask C contains lactose. After a few hours of incubation, you test the flasks for the presence of ß-galactosidase. Which flask(s) do you predict will have this enzyme?
a. A
b. B
c. C
d. A and B
e. B and C
Problem 10.5a
NAME IT Use the key in the Clinical Focus box to identify the gram-negative, oxidase-positive rod causing pneumonia in a sea otter. It is H₂S-positive, indole-negative, and urease-positive.
Problem 11.10a
Unlike purple and green phototrophic bacteria, cyanobacteria
a. produce oxygen during photosynthesis.
b. do not require light.
c. use H₂S as an electron donor.
d. have a membrane-enclosed nucleus.
e. all of the above
