Week 6 Questions (Exam 2)

If the citric acid cycle was interrupted after the reaction that forms citrate, predict how this would affect the total amount of ATP generated per glucose molecule. The amount of ATP would be reduced from a total of 38 ATP to 8 ATP. The amount of ATP would be reduced from a total of 38 ATP to 30 ATP. The amount of ATP would be reduced from a total of 38 ATP to 22 ATP. The amount of ATP would be reduced from a total of 38 ATP to 14

What occurs at the bridge step in the CAC? The production of GTP Decarboxylation of pyruvic acid The formation of oxaloacetate The formation of succinyl CoA

Based on the animation, how many electron carriers are reduced in the Krebs cycle only? Three Five Six Four

What is the function of GTP? A scaffolding for carbon atoms An electron carrier An oxidizer to produce CO2 An energy carrier

What is the fate of metabolites during respiration? They are rearranged to form GTP. They are oxidized completely to form pyruvic acid. They are reduced to from NADH and FADH2. They are oxidized completely to carbon dioxide and water.

Which of the following is needed as a reactant for the first step of the citric acid cycle? Oxaloacetic acid Malic acid Succinyl CoA Citric acid

Where does the energy come from to power the formation of GTP? ATP Water NADH Succinyl CoA

Which step involves the release of carbon dioxide? The seventh step The first and eighth steps The second step The third and fourth steps

How many molecules of ATP can be generated from one molecule of NADH? Three One Two Four

Which step(s) of the Krebs cycle does (do) not produce any usable energy? The sixth step The third step The first and eighth steps The second and seventh steps The fifth step

How is anaerobic respiration different from aerobic respiration? The terminal electron acceptor in anaerobic respiration is not oxygen. The terminal electron acceptors are the same, but the chemical reactions are different. The terminal electron acceptor in anaerobic respiration is oxygen. The two processes are identical. The only difference is the presence or absence of oxygen.

Steps of electron transport chain

The proton motive force (PMF) is driven by __________. the difference in charge across the plasma membrane with protons outside the membrane the pumping of protons through the plasma membrane the pumping of electrons though the plasma membrane the difference in charge across the plasma membrane with electrons outside the membrane

Depending on the particular metabolism of a bacterium, electron transport can be used to energize and rotate ATP synthase. True False

The terminating step of moving electrons onto oxygen releases additional ATP during aerobic metabolism not made during anaerobic growth. True False

n electron transport systems, the electron carriers are membrane associated. True False

The net result of electron transport is the generation of a pH gradient and an electrochemical potential across the membrane. True False

Why does lack of oxygen result in the halt of ATP synthesis in the ETC? Oxygen prevents uncoupling of the electron transport chain. It causes one of the cytochromes in the electron transport chain to be permanently stuck in the reduced state. The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained.

Why might some cells uncouple the electron transport chain? Uncoupling proteins offset the effect of cyanide. Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation. A cell does not require ATP. Too much ATP is bad for the cell.

How does cyanide poisoning result in the decrease of ATP production? Cyanide permanently binds to oxygen, preventing its use as the final electron acceptor. Cyanide permanently oxidizes cytochrome a3, preventing other components to change into the reduced state. This causes the proton gradient to break down, stopping ATP synthesis. Cyanide permanently reduces cytochrome a3, preventing other components to change into the oxidized state. This causes the proton gradient to break down, stopping ATP synthesis. Cyanide uncouples the proton gradient from the process of ATP synthesis.

Which of the following situations does not result in a breakdown of the proton gradient? Oxygen deprivation Cyanide poisoning Uncoupling proteins

Which is one major difference between anaerobic and aerobic respiration? electron acceptor use of proton motive force use of electron transport electron donor

Which metabolic strategy does NOT invoke the proton motive force for energy conservation? fermentation chemoorganotrophy photoautrophy aerobic catabolism

Cellular respiration Inputs and outputs

Whether a molecule is oxidized or reduced in a redox reaction depends on its reduction potential relative to the available electron donors and acceptors present that the organism can utilize. Given the following reduction potentials for various redox half reactions, in a lithotroph capable of utilizing ammonia as an energy source, which substances would be potential terminal electron acceptors for respiration? NO2 -/NH3 +0.34 V NO3 -/NO2 - +0.43 V O2/H2O +0.82 V O2 NO3 - NO2 - Both O2 and NO3 - are possible electron acceptors

Because H2 levels in oxic environments are transient, it is likely that aerobic hydrogen bacteria shift between chemoorganotrophy and chemolithotrophy depending on levels of organic compounds and hydrogen in their habitats. True False

In Bacteria, the most common oxidized form of nitrogen is ________ and of sulfur is ________. nitrate / sulfate nitrite / sulfate nitrate / sulfite nitrite / sulfite

Some organisms are capable of using aerobic respiration or anaerobic respiration but use aerobic respiration preferentially. Why is aerobic respiration favored? Aerobic respiration generates more oxygen, which is needed by many organisms. Using aerobic respiration allows them to use fermentation as well. Respiration with oxygen as a terminal electron acceptor generates more energy than respiration with other terminal electron acceptors. It is more efficient to focus on one process than to use two simultaneously, so aerobic respiration is the default and anaerobic respiration is used only as a backup.

Gluconeogenesis is the process of synthesizing __________. glucose from other compounds proteins from glucose polysaccharide slime from glucose glucose from genes

Which two metabolic processes are most dissimilar? proton motive force and substrate-level phosphorylation glycolysis and gluconeogenesis citric acid cycle and glycolysis pentose phosphate pathway and glycolysis

Since glucose, a hexose, is the major source of energy for most prokaryotes, why would they need to have pentose sugars available? Pentose sugars are needed for transport processes. Pentose sugars are needed for protein synthesis. Pentose sugars are needed for nucleic acid synthesis. Pentose sugars are needed for membrane synthesis.

Catabolic pathways are essential for microorganisms to obtain energy, because biosynthetic reactions for cellular growth generally require energy input. True False

With respect to nitrogen utilization, relatively few bacteria can use NH3 whereas many more can make use of N2. True False

Which metabolic cycle or pathway is LEAST likely to be invoked during the biosynthesis of DNA? pentose phosphate pathway gluconeogenesis citric acid cycle glycolysis

Most of the carbon in amino acid biosynthesis comes from glycolysis products. glycolysis intermediates and products. citric acid cycle intermediates and glycolysis products. citric acid cycle intermediates.

A bacterium that lacks an arginine biosynthetic pathway would still be able to make proteins with arginine and grow only if arginine is supplemented into the growth medium. True False

Improperly functioning acyl carrier proteins (ACPs) would likely result in no harm to bacteria, because only archaeons and eukaryotes use ACPs for fatty acid biosynthesis. death for a bacterium due to poor lipid bilayer integrity. enhanced growth of a bacterium due to faster growth substrate uptake by a weakened membrane. a physiological shift to anaerobic metabolism where an energized membrane is less important for energy production.

Many defined growth media that support microbial growth lack malonate, which is an important precursor for biosynthesis of lipid membranes. Based on this, we can infer cells also must have a metabolic pathway to generate malonate from other compounds. True False