Chapter 5 Mastering Microbiology Homework
Which of the following statements regarding competitive inhibitors is true? - The inhibitor will degrade the substrate. - The inhibitor will destroy the substrate. - Competitive inhibitors decrease the rate of enzyme activity. - The inhibitor will destroy the enzyme.
Competitive inhibitors decrease the rate of enzyme activity.
What enables competitive inhibitors to bind to a specific enzyme? - Competitive inhibitors have structures that resemble the enzyme's substrate. - Competitive inhibitors have unique sugars that are attracted to the enzyme. - Competitive inhibitors cover the entire surface of an enzyme. - Competitive inhibitors form unique covalent bonds with enzyme structures.
Competitive inhibitors have structures that resemble the enzyme's substrate.
Why do all enzymatic reactions need activation energy? Energy allows only the substrate to bind. Energy is required to disrupt a substrate's stable electron configuration. Energy is needed for the enzyme to find its substrate. Energy is required by an enzyme so that it can be reused.
Energy is required to disrupt a substrate's stable electron configuration.
Why are enzymes important to biological systems? Enzymes prevent unwanted chemical by-products from forming. Enzymes decrease the amount of activation energy required for chemical reactions to occur. Enzymes increase the energy barrier required of chemical reactions. Enzymes are reuseable.
Enzymes decrease the amount of activation energy required for chemical reactions to occur.
What is meant by the statement "Enzymes are biological catalysts"? Enzymes speed up the chemical reactions in living cells. Enzymes produce products useful for biology. Enzymes are products of biological systems. Enzymes produce biological organisms.
Enzymes speed up the chemical reactions in living cells.
(True/False) The following statement correctly applies to aerobic respiration: A total of 2 ATP are produced per molecule of glucose input.
False
(True/False) The following statement correctly applies to aerobic respiration: Between 2 and 38 ATP are produced per molecule of glucose input.
False
(True/False) The following statement correctly applies to aerobic respiration: Can generate ATP in the absence of O2.
False
(True/False) The following statement correctly applies to aerobic respiration: End products may include lactic acid or ethanol.
False
(True/False) The following statement correctly applies to anaerobic respiration: A total of 2 ATP are produced per molecule of glucose input.
False
(True/False) The following statement correctly applies to anaerobic respiration: A total of 38 ATP are produced per molecule of glucose input.
False
(True/False) The following statement correctly applies to anaerobic respiration: End products are CO2 and H2O
False
(True/False) The following statement correctly applies to anaerobic respiration: End products may include lactic acid or ethanol.
False
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: A toxin that causes a leak to form in the inner mitochondrial membrane such that protons could bypass the ATP synthase would disrupt the flow of electrons to O2.
False
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: ATP serves as an electron carrier in the electron transport chain.
False
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: Electrons moving from the FMN to Q to cytochrome b are gaining energy.
False
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: The electrons carried by FADH2 have more potential energy than those carried by NADH.
False
If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected? Sulfanilamide products will be in higher concentration. PABA will not be catalyzed. PABA products will increase in concentration. The substrate will destroy the inhibitor.
PABA will not be catalyzed.
Which of the following statements regarding redox reactions is true? Redox reactions are only seen in the electron transport chain. Redox reactions involve an oxidation reaction coupled with a reduction reaction. Redox reactions must either be oxidizing reactions or reducing reactions. No metabolic reactions are redox reactions.
Redox reactions involve an oxidation reaction coupled with a reduction reaction.
Consider the glycolysis pathway. Select all statements that correctly describe glycolysis This process occurs in the mitochondria of eukaryotic cells. CO2 is produced during glycolysis.The 6-carbon skeleton of glucose is enzymatically split into two 3-carbon compounds. Glyceraldehyde 3-phosphate is oxidized, and NAD+ is reduced to NADH. More ATP is formed than is consumed in this process. Glucose is the original electron donor.Each of the 10 steps in this pathway is catalyzed by the same enzyme. Pyruvate is the electron acceptor.
The 6-carbon skeleton of glucose is enzymatically split into two 3-carbon compounds. Glyceraldehyde 3-phosphate is oxidized, and NAD+ is reduced to NADH. More ATP is formed than is consumed in this process. Glucose is the original electron donor. The pyruvic acid that is formed during the last step of glycolysis may be converted to acetyl CoA and enter into Krebs cycle to continue with cellular respiration, or it may enter into fermentation reactions. The specific outcome will depend on the presence of O2 and the specific enzymes in the cell.
A key feature of cellular respiration is the removal of electrons from fuel molecules (oxidation) and the ultimate acceptance of these electrons by a low-energy electron acceptor. The process involves the use of electron carriers, NAD+ and FAD, which play crucial roles in multiple steps of the metabolic pathways. The overall equation for cell respiration is shown below. Why do NAD+ and FAD NOT appear in the overall equation? ADP is the electron carrier in this pathway and picks up electrons to form ATP. The NAD+ and FAD are initially reduced then oxidized to their original state, so they do not appear in the net equation. Glucose and CO2 are the electron carriers in this pathway. This pathway doesn't use electron carriers such as NAD+ and FAD and uses only the electron transport chain.
The NAD+ and FAD are initially reduced then oxidized to their original state, so they do not appear in the net equation. At least 10 NAD+ and 2 FAD are used in the cellular respiration pathway. They pick up electrons during oxidation reactions in glycolysis, oxidation of pyruvate to form acetyl CoA, and the Krebs cycle, and then they give up these electrons to the electron transport chain. They don't appear in the net reaction equation because all of the NAD+ and FAD that enter into the reactions are oxidized back to their original form when they give up their electrons.
Why is reduction the term used to describe the gain of an electron? The amount of energy in the molecule decreases. The electron acceptor's net charge decreases. The electron acceptor gets smaller. The number of molecules in the reaction decreases.
The electron acceptor's net charge decreases.
Which of the following best describes the role of the gut microbiome in human digestion? The gut microbiome produces ATP for human cells. The gut microbiome breaks down dietary compounds that human metabolic enzymes cannot break down. The gut microbiome reduces the production of intestinal gases. The gut microbiome does not contribute to human digestion.
The gut microbiome breaks down dietary compounds that human metabolic enzymes cannot break down. The gut microbiome is an important component of our digestive system. It breaks down many compounds that our own digestive enzymes cannot handle. It also provides us with certain vitamins and assists our immune system.
How does a competitive inhibitor slow enzyme catalysis? - They compete with the substrate for the enzyme's active site. - They produce products toxic to the enzymes. - They degrade the substrate. - They bind to the substrate.
They compete with the substrate for the enzyme's active site.
What is the main function of fermentation? To regenerate NAD+ for glycolysis. To produce sugars for ATP generation. To generate acetyl CoA for the Krebs cycle. To regenerate NADH for the electron transport chain.
To regenerate NAD+ for glycolysis. In the absence of O2, the electron carrier NADH accumulates, effectively lowering the available NAD+. Fermentation uses pyruvate and its derivatives to oxidize NADH to regenerate NAD+ for glycolysis.
(True/False) The following statement correctly applies to aerobic respiration: A total of 38 ATP are produced per molecule of glucose input.
True
(True/False) The following statement correctly applies to aerobic respiration: End products are CO2 and H2O Submit
True
(True/False) The following statement correctly applies to aerobic respiration: Much or most of the ATP produced is produced by oxidative phosphorylation.
True
(True/False) The following statement correctly applies to aerobic respiration: Process includes glycolysis
True
(True/False) The following statement correctly applies to aerobic respiration: Process involves electron transport and chemiosmosis
True
(True/False) The following statement correctly applies to aerobic respiration: Process involves the Krebs cycle
True
(True/False) The following statement correctly applies to aerobic respiration: The coenzyme NAD+ plays an important role in the pathway.
True
(True/False) The following statement correctly applies to anaerobic respiration: Between 2 and 38 ATP are produced per molecule of glucose input.
True
(True/False) The following statement correctly applies to anaerobic respiration: Can generate ATP in the absence of O2.
True
(True/False) The following statement correctly applies to anaerobic respiration: Much or most of the ATP produced is produced by oxidative phosphorylation.
True
(True/False) The following statement correctly applies to anaerobic respiration: Process includes glycolysis
True
(True/False) The following statement correctly applies to anaerobic respiration: Process involves electron transport and chemiosmosis
True
(True/False) The following statement correctly applies to anaerobic respiration: Process involves the Krebs cycle
True
(True/False) The following statement correctly applies to anaerobic respiration: The coenzyme NAD+ plays an important role in the pathway.
True
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: A chemical that inactivates cytochrome c so that it can't pass electrons on to cytochrome a would block electron transport and ATP synthesis.
True
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: A toxin that causes a leak to form in the inner mitochondrial membrane such that protons could bypass the ATP synthase would prevent oxidative phosphorylation.
True
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: The final electron acceptor is O2.
True
(True/False) The following statement correctly describes some aspect of the electron transport chain and chemiosmosis: The pH of the intermembrane space in mitochondria would be lower than the pH of the mitochondrial matrix in an actively metabolizing cell.
True
A reaction that involves the transfer of electrons from one molecule to another is referred to as: a redox reaction. an oxidation reaction. a reduction reaction.
a redox reaction.
Arrange the basic processes of cellular respiration in the order they occur:
glycolysis, Krebs cycle, electron transport chain and chemiosmosis.
During an oxidation reaction, the acceptor molecule gains an electron and becomes oxidized. the acceptor molecule loses an electron and becomes oxidized. the donor molecule gains an electron and becomes oxidized. the donor molecule loses an electron and becomes oxidized.
the donor molecule loses an electron and becomes oxidized.
Choose the following statements that correctly apply to fermentation: End products are CO2 and H2O The coenzyme NAD+ plays an important role in the pathway. Process involves the Krebs cycle A total of 38 ATP are produced per molecule of glucose input. Between 2 and 38 ATP are produced per molecule of glucose input. Process involves electron transport and chemiosmosis Process includes glycolysis Can generate ATP in the absence of O2. End products may include lactic acid or ethanol. A total of 2 ATP are produced per molecule of glucose input. Much or most of the ATP produced is produced by oxidative phosphorylation.
• A total of 2 ATP are produced per molecule of glucose input .• End products may include lactic acid or ethanol. • Can generate ATP in the absence of O2 .• The coenzyme NAD+ plays an important role in the pathway. • Process includes glycolysis Some microorganisms rely on just one of these metabolic processes. For example, Pseudomonas spp. use aerobic respiration to release energy from glucose. Other microorganisms possess multiple metabolic pathways and maybe able to do aerobic respiration in the presence of O2, but when deprived of O2 will revert to anaerobic respiration and/or fermentation. Other microorganisms rely entirely on fermentation.
Select all statements that correctly describe the preparatory step and the Krebs cycle
• The oxaloacetic acid that accepts the acetyl group is regenerated, enabling the cyclic nature of this process • The potential energy in the pyruvate is transferred to coenzymes NAD+ and FAD • The equivalent of one ATP is made for each turn of the Krebs cycle • It takes two "turns" of the Krebs cycle to process the pyruvic acid molecules resulting from the glycolysis of one glucose molecule • Carbons from pyruvic acid end up as CO2 • There are five oxidation-reduction reactions depicted You have identified correct statements about the Krebs cycle. At this point, most of the potential energy that was originally in the glucose molecule is now in the electrons carried by NADH and FADH2. The next process will involve moving the electrons from these coenzymes down a series of electron carriers until they reach their lowest energy level in the final electron acceptor. The energy given up by the electrons will be use to phosphorylate ADP to make ATP.
