Q: Which of the following reactions is an example of substrate-level phosphorylation (SLP) in microbial metabolism?

$$\text{ADP}^{3-} + \text{P}_i$$^{2-}$$ + \text{H}^+ \rightarrow \text{ATP}^{4-} + \text{H}_2\text{O}$$

Q: A microbe is fermenting glucose to ethanol and carbon dioxide. Which of the following equations best represents the overall process?

$$\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{CH}_3\text{CH}_2\text{OH} + 2\text{CO}_2 + \text{energy}$$

Q: Which of the following is a correct pattern for the oxidative decarboxylation of an alpha-keto acid?

$$\text{R-CO-COOH} \rightarrow \text{R-COOH} + \text{CO}_2$$

Q: Which of the following is a correct equation for the oxidation of glucose to pyruvate during glycolysis?

$$\text{C}_6\text{H}_{12}\text{O}_6 + 2\text{NAD}^+ \rightarrow 2\text{CH}_3\text{COCOO}^- + 2\text{NADH} + 2\text{H}^+$$

Question 1

Which of the following best describes the main difference between fermentation and respiration in microbial metabolism?

Accepted Answer

Fermentation generates ATP primarily through substrate-level phosphorylation, while respiration uses an electron transport chain to generate a proton motive force.

Question 2

Which of the following reactions is an example of substrate-level phosphorylation (SLP) in microbial metabolism?

Accepted Answer

$$	ext{ADP}^{3-} + 	ext{P}_i$$^{2-}$$ + 	ext{H}^+ ightarrow 	ext{ATP}^{4-} + 	ext{H}_2	ext{O}$$

Question 3

A microbe is fermenting glucose to ethanol and carbon dioxide. Which of the following equations best represents the overall process?

Accepted Answer

$$	ext{C}_6	ext{H}_{12}	ext{O}_6 ightarrow 2	ext{CH}_3	ext{CH}_2	ext{OH} + 2	ext{CO}_2 + 	ext{energy}$$

Question 4

Which of the following is NOT a typical product of microbial fermentation?

Accepted Answer

Oxygen

Question 5

During the catabolism of fats, which molecule is repeatedly generated and then used in the TCA cycle to produce reducing power?

Accepted Answer

Acetyl-CoA

Question 6

Which of the following statements about lyase-catalyzed reactions is correct?

Accepted Answer

Lyases catalyze the cutting of bonds without involving redox chemistry.

Question 7

Which of the following is the correct oxidation number for carbon in methane ($$	ext{CH}_4$$)?

Accepted Answer

-4

Question 8

In the context of fermentation, what is the main purpose of balancing redox reactions?

Accepted Answer

To ensure that all electrons removed from the substrate are accounted for in the products

Question 9

Which of the following bonds in ATP is considered 'high-energy' and is directly involved in energy transfer?

Accepted Answer

Anhydride bond

Question 10

A bacterium is growing anaerobically on glucose and produces butanediol, formic acid, and CO$$_2. If $$the total oxidation number of the products is nearly equal to that of the substrate, what does this indicate?

Accepted Answer

The redox balance of the fermentation is nearly complete.

Question 11

Which of the following is a correct pattern for the oxidative decarboxylation of an alpha-keto acid?

Accepted Answer

$$	ext{R-CO-COOH} ightarrow 	ext{R-COOH} + 	ext{CO}_2$$

Question 12

Which of the following best explains why energy yields from fermentation are lower than those from respiration?

Accepted Answer

Fermentation lacks a terminal electron acceptor and does not generate a proton motive force.

Question 13

Which of the following is a typical sequence in the microbial degradation of a substrate for energy conservation?

Accepted Answer

Activate substrate, rearrange C skeleton, oxidize, couple to SLP, balance redox, excrete products

Question 14

Which of the following is a correct equation for the oxidation of glucose to pyruvate during glycolysis?

Accepted Answer

$$	ext{C}_6	ext{H}_{12}	ext{O}_6 + 2	ext{NAD}^+ ightarrow 2	ext{CH}_3	ext{COCOO}^- + 2	ext{NADH} + 2	ext{H}^+$$

Question 15

Which of the following is a common high-energy intermediate used in substrate-level phosphorylation?

Accepted Answer

1,3-Bisphosphoglycerate

Question 16

Which of the following is NOT a step in the general strategy for microbial degradation of organic substrates?

Accepted Answer

Direct use of oxygen as a substrate

Question 17

Which of the following is a correct pattern for the oxidation of a saturated bond between two methylene groups?

Accepted Answer

$$-	ext{CH}_2-	ext{CH}_2- ightarrow -	ext{CH}=	ext{CH}-$$

Question 18

Which of the following is a benefit to the cell from the TCA cycle?

Accepted Answer

Generation of reducing power for the electron transport system

Lectures 18 and 19

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