12. Microbial Metabolism

Which product of the Krebs cycle is also used as a reactant in the Krebs cycle?

a) Citrate.

b) ATP.

c) Acetyl-CoA.

d) Oxaloacetate.

Taking one molecule of glucose through glycolysis, pyruvate oxidation, and the Krebs cycle generates:

a) 6 CO₂, 8 NADH, 2 FADH₂ and 4 ATP.

b) 6 CO₂, 8 NADH, 1 FADH₂ and 2 ATP. 

c)  6 CO₂, 10 NADH, 2 FADH₂ and 4 ATP.  

d) 6 CO₂, 10 NADH, 2 FADH₂ and 2 ATP.

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.

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

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

_______ is a cyclic series of eight reactions involved in the catabolism of acetyl-CoA that yields eight molecules of NADH and two molecules of FADH2.