Bio 203 Ch 9

Both cellular respiration and fermentation

-NAD+ is produced -NADH is produced -ATP is produced -Glucose is oxidized

oxidative phosphorylation

-occurs under the action of ATP synthase -occurs when electrons move through and ETC and produce a proton-motive force that drives ATP synthase

substrate-level phosphorylation

-occurs under the action of pyruvate kinsase and phosphoglycerate kinase -occurs when enzymes remove a high-energy phosphate from a substrate and directly transfer it into ADP

How many NADH are produced by glycolysis? a. 2 b. 1 c. 5 d. 3 e. 4

a. 2 two NADH molecules are produced by glycolysis

Why is ATP production during cellular respiration characterized as indirect? a. ATP is not produced directly by the ETC but instead via the proton gradient generated during electron transport through the ETC. b. Most of the ATP is produced during glucose oxidation, which occurs through a series of intermediate steps. c. ATP is produced by enzymes indirectly associated with the ETC that perform substrate-level phosphorylation. d. Electrons are not passed directly from NADH and FADH2 to O2 but indirectly through the ETC.

a. ATP is not produced directly by the ETC but instead via the proton gradient generated during electron transport through ETC. Biologists characterize ATP production as indirect because ATP is NOT synthesized by the ETC (or associated enzymes) via substrate-level phosophorylation

What is produced as a waste product of pyruvate processing? a. CO2 b. water c. amino acids d. NADH

a. CO2 CO2 is a waste product of cellular respiration created in the pyruvate processing and the citric acid cycle steps

What happens to glycolysis as ATP binds to phosphofructokinase at the allosteric regulatory site? a. it inhibits the reaction b. it allows the reaction to continue c. it speeds up the reaction rate d. it has no effect on the rate of glycolysis

a. It inhibits the reaction When ATP concentrations increase, the enzyme is inhibited to allow for the conservation of glucose.

Which of the following products of cellular respiration would accumulate if there were no final electron acceptor in the ETC? a. NADH b. NAD+ c. ATP d. pyruvate

a. NADH If there were no final electron acceptor, the ETC would no longer oxidize NADH to NAD+, which would result in an accumulation of NADH

Which of the following is true of NADH and FADH2? a. NADH has more potential energy than FADH2 b. Only NADH donates electrons to the ETC c. Only FADH2 can become oxidized d. Only NADH is produced in the citric acid cycle

a. NADH has more potential energy than FADH2 Indicated in figure 9.14

Which of these enters the citric acid cycle? a. acetyl CoA b. pyruvate c. G3P d. NADH + H e. glucose

a. acetyl CoA Acetyl CoA is a reactant in the citric acid cycle

If a cell is treated with a drug that inhibits ATP synthase, the pH in the mitochondrial intermembrane space will _____. a. decrease b. it is impossible to determine what will happen to the pH c. not change d. increase

a. decrease Hydrogen ions are pumped from the matrix to the intermembrane space as electrons are transferred from NADH to oxygen. This will continue to happen for some time after ATP synthesis is blocked

Which enzymes in glycolysis consume ATP to allow for full transition of glucose to pyruvate? a. Hexokinase and phosphofructokinase b. Phosphoglucose isomerase and triose phosphate isomerase c. Glyceraldehyde-3-phophate dehydrogenase and phosphoglycerate mutase d. Phosphoglycerate kinase and pyruvate kinase

a. hexokinase and phosphofructokinase These enzymes are kinases that consume ATP to phosphorylate target molecules.

Which of the following is true of glycolysis? a. It leads to the reduction of NAD+ b. It occurs in the matrix of mitochondria c. ATP is produced via oxidative phosphorylation d. It only requires five distinct enzymes

a. it leads to the reduction of NAD+ NAD+ is reduced to NADH as glyceraldehyde-3-phosphate is phosphorylated in step 6

In muscle cells, fermentation produces _____. a. lactate and NAD+ b. lactate, NADH, and ATP c. carbon dioxide, ethanol, NADH, and ATP d. carbon dioxide, ethanol, and NAD+pyruvate

a. lactate and NAD+ These a re products of fermentation as it occurs in muscle cells

In glycolysis, ATP molecules are produced by ______. a. substrate-level phosphorylation b. oxidative phosphorylation c. photosynthesis d. photophosphorylation e. cellular respiration

a. substrate-level phosphorylation a phosphate group is transferred from glyveraldehyde phosphate to ADP

Which mode of energy production is most efficient (produces the most ATP) per glucose? a. They all produce the same amount of ATP because they can all start with the same initial substrate, glucose. b. Aerobic respiration c. Anaerobic respiration d. Fermentation

b. Aerobic respiration Aerobic respiration can produce about 29 ATP per glucose, more than other methods listed

A substrate-level phosphoylation occurs in the citric acid cycle when ____. a. NAD+ is phosphorylated to NADH b. GDP is phosphorylated to produce GTP c. acetylation of oxaloacetate takes place d. oxaloacetate is phosphorylated

b. GDP is phosphorylated to produce GTP

In the phosphofructokinase molecule shown in Figure 9.7, the active site has a higher affinity for ATP than the regulatory site does. Which answer best summarizes what the consequences would be if the regulatory site had a higher affinity for ATP than the active site did? a. Glucose oxidation would occur faster at low ATP concentrations. b. Glucose oxidation would be inhibited even if ATP were scarce in the cell. c. Glucose oxidation would be inhibited only at high ATP concentrations. d. Glucose oxidation would occur via a completely different metabolic pathway

b. Glucose oxidation would be inhibited even if ATP were scarce in the cell Because regulatory site has a higher affinity for ATP, more enzyme molecules would be inhibited at low ATP concentrations

According to the chemiosmotic hypothesis, ATP can be produced without an electron transport chain as long as which conditions are met? Assume the ADP and Pi are available in all conditions. a. ATP synthase and NADH are present. b. Membrane-embedded ATP synthase and a proton motive force are present. c. A proton motive force and enzymes capable of substrate-level phosphorylation are present. d. Glucose and oxygen are present.

b. Membrane-embedded ATP synthase and a proton motive force are present ATP synthase can produce ATP via protons flowing through it down their electrochemical potential

If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production? a. There would be no change in ATP production, but we would observe an increased rate of carbon dioxide production. b. The rates of ATP production and carbon dioxide production would both increase. c. The rate of ATP production would decrease, but the rate of carbon dioxide production would increase. d. Rates of ATP and carbon dioxide production would probably both decrease

b. The rates of ATP production and carbon dioxide production would both increase.

Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in ____. a. nonphotosynthesizing cells only b. all cells all the time c. cells that are storing glucose only d. photosynthetic cells in the light, while photosynthesis occurs concurrently e. photosynthesizing cells in the light and in other tissues in the dark

b. all cells all the time

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of ___. a. allosteric regulation b. an endergonic reaction coupled to an exergonic reaction c. osmosisactive transport d. a reaction with a positive ΔG

b. an endergonic reaction coupled

Glycolysis is active when cellular energy levels are ____; the regulatory enzyme, phosphofructokinase is ____ a. high; inhibited b. low; inhibited c. low: activated d. high; activated

b. low; inhibited

When electrons flow along the ETC of mitochondria, which of the following changes occurs? a. the electrons gain free energy b. the pH of the matrix increases c. NAD+ is oxidized d. the cytochromes phosphorylate ADP to form ATP. e. ATP synthase pumps protons by active transport

b. the pH of the matrix increases

Which of the following statements is true for prokaryotes that perform aerobic respiration? a. they are unable to use oxygen b. they oxidize NADH at the plasma membrane c. these prokaryotes contain mitochondria d. they do not make ATP

b. they oxidize NADH at the plasma membrane The ETC is embedded in the plasma membrane of the prokaryotic cell

If you were to expose cells that are undergoing aerobic respiration to a radioactive oxygen isotope in the form of O2, which of the following molecules would you expect to be radioactively labeled? a. C6H12O6 b. water c. CO2 d. pyruvate

b. water O2 is reduced to H2O during aerobic respiration, and so the oxygen atoms end up in water and so would be radiolabeled

In glycolysis there is a net gain of _____ ATP a. 5 b. 1 c. 2 d. 4 e. 5

c. 2 It takes 2 ATP to produce 4 ATP

Which of the following compounds inhibits pyruvate dehydrogenase via feedback inhibition? a. AMP b. Coenzyme A c. Acetyl CoA d. Pyruvate

c. Acetyl CoA Acetyl CoA is a product that can feed back to inhibit pyruvate dehydrogenase

What does substrate-level phosphorylation and oxidative phosphorylation have in common? a. both processes produce NADPH from NADH and Pi b. Both processes occur under the action of ATP synthase c. Both processes produce ATP from ADP and Pi d. Both processes occur in the matrix of mitochondria

c. Both processes produce ATP from ADP and Pi

If glucose is fully labeled with C14 (a radioisotope of carbon), what molecule will become radioactive as glycolysis and the citric acid cycle are completed? a. water b. NADH c. CO2 d. ATP

c. CO2 All of the carbons of glucose become oxidized into carbon dioxide, two as pyruvate becomes acetyl CoA and four during the citric acid cycle

Under which conditions will the citric acid cycle be activated? a. High levels of NADH b. High levels of ATP c. High levels of AMP d. The citric acid cycle is not regulated; it just runs at a constant rate

c. High levels of AMP High levels of AMP stimulate pyruvate dehydrogenase, so the citric acid cycle would be activated because more acetyl CoA would be available

Which pathways of cellular respiration must a carbohydrate processed through to be useful as a substrate for nucleotide synthesis? a. They must proceed through all of pyruvate processing. b. Glucose must proceed through all of glycolysis. c. It only needs to proceed through the first few steps of glycolysis. d. It must proceed through the citric acid cycle.

c. It only needs to proceed through the first few steps of glycolysis Glucose is quickly converted into a useful substrate for nucleotide synthesis

The energy of electron transport serves to move (translocate) protons to the outer mitochondrial compartment. How does this help the mitochondrion produce ATP? a. The protons receive electrons from the NAD+ and FAD that are accepted by electrons in glycolysis and the citric acid cycle. b. The protons pick up electrons from the electron transport chain on their way through the inner mitochondrial membrane. c. The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria. d. The hydrogen ions (protons) are transferred to oxygen in an energy-releasing reaction.

c. The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria.

During cellular respiration, the carbons initially present in pyruvate are derived from ____ and are ultimately converted to ____. a. acetyl CoA; CO2 b. NAD+; ATP c. glucose; CO2 d. glucose; ATP

c. glucose; CO2 Glycolysis converts glucose to pyruvate. Pyruvate processing and the citric acid cycle lead to the complete oxidation of the carbons in pyruvate into CO2

Which stage of cellular respiration is also part of fermentation? a. oxidative phosphorylation b. citric acid cycle c. glycolysis d. pyruvate processing

c. glycolysis In both cellular respiration and fermentation, glycolysis oxidizes glucose to produce pyruvate and ATP

What will happen to the concentration of lactate if a human muscle cell runs out of oxygen? a. it is impossible to predict what will happen to the concentration of lactate b. lactate levels will decrease c. lactate levels will increase d. lactate levels will not change

c. lactate levels will increase If oxygen is unavailable as a final electron acceptor, pyruvate accepts electrons and is reduced to lactate

If a proton ionophore, a molecule that forms an artificial channel allowing hydrogen ions to cross membranes, is inserted into the inner mitochondrial membrane, what happens to the concentration of ATP in a cell? a. It is impossible to determine what will happen to ATP levels b. The ATP levels increase c. The ATP levels decrease d. The ATP levels do not change

c. the ATP levels decrease The ionophere prevents the buildup of hydrogen ions necessary for ATP synthesis

In glycolysis, what starts the process of glucose oxidation? a. NADPH b. hexokinase c. FADH2 d. ATP e. ADP

d. ATP Some ATP energy is used to start the process of glucose oxidation

Which of these is NOT a product of glycolysis a. ATP b. pyruvate c. NADH d. FADH2

d. FADH2 FADH1 is a product of the citric acid cycle

What purpose does fermentation serve? a. It produces an abundance of ATP when oxygen is present. b. It allows for the production of NADH, which keeps the electron transport chain going. c. Under aerobic conditions, it drives the formation of acetyl-CoA, which then feeds into the citric acid cycle. d. It regenerates NAD+ from NADH to keep glycolysis going in the absence of oxygen.

d. It regenerates NAD+ from NADH to keep glycolysis going in the absence of oxygen. Fermentation us unlikely to occur when oxygen is available as the final electron acceptor at the end of the ETC

As shown in Figure 9.10, citrate is the initial carboxylic acid in the citric acid pathway and oxaloacetate is the final carboxylic acid. To determine if the citric acid pathway was cyclic, Krebs treated cells with radioactive oxaloacetate. What would have been the result of Krebs's experiment if the pathway were linear instead of circular? a. Radioactive oxaloacetate + acetyl CoA would produce radioactive citric acid. b. Radioactive oxaloacetate would produce radioactive acetyl CoA. c. Radioactive oxaloacetate + acetyl CoA would produce radioactive glucose. d. Radioactive oxaloacetate + acetyl CoA would produce no radioactive citric acid cycle intermediates.

d. Radioactive oxaloacetate + acetyl CoA would produce no radioactive citric acid cycle intermediates If the cycle were linear, oxaloacetate would not react with pyruvate to produce earlier compounds in the pathway

Which of the following statements correctly identifies why fermentation alone won't keep cells alive? a. Fermentation stores harvested energy in NADH, which has low potential energy. b. Fermentation can produce lactic acid, which is toxic to cells. c. Fermentation can produce ethanol and CO2, which are toxic to cells. d. The oxidation of glucose via cellular respiration has the potential yield of 29 ATP while the oxidation of glucose via fermentation yields only 2 ATP

d. The oxidation of glucose via cellular respiration has the potential yield of 29 ATP while the oxidation of glucose via fermentation yields only 2 ATP Cellular respiration is much more efficient at harvesting potential energy from glucose

If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production? a. The rate of ATP production would decrease, but the rate of carbon dioxide production would increase. b. There would be no change in ATP production, but we would observe an increased rate of carbon dioxide production. c. Rates of ATP and carbon dioxide production would both decrease. d. The rates of ATP production and carbon dioxide production would both increase.

d. The rates of ATP production and carbon dioxide production would both increase

Which of these is NOT a product of the citric acid cycle? a. CO2 b. ATP c. FADH2 d. Acetyl CoA e. NADH + H

d. acetyl CoA Acetyl CoA enters the citric acid cycle

In the Buchner experiment, why did boiling of the yeast extract prevent the processing of sugar? a. yeast cells were killed b. sucrose was destroyed c. phosphate required for the reactions was destroyed d. proteins were denatured

d. proteins were denatured the enzymes required to catalyze the reactions were proteins, which were denatured by boiling

One of the purposes of the citric acid cycle is to ____. a. oxidize NAD+ b. oxidize NADH c. reduce NADH d. reduce NAD+

d. reduce NAD+ This reaction produces NADH, which is then used in oxidative phosphorylation to generate ATP

During which phases of cellular respiration is ATP produced via oxidative phosphorylation instead of substrate level phosphorylation? a. Pyruvate processing and the citric acid cycle b. Glycolysis and pyruvate processing c. Glycolysis and the citric acid cycle d. The electron transport chain

d. the electron transport chain ATP is produced by oxidative phosphorylation, not via substrate-level phosphorylation, during the electron transport chain

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to _____. a. activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle. b. inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle. c. activate the enzyme and thus increase the rates of glycolysis and the citric acid cycle. d. inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate. e. inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.

e. inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.

In fermentation ____ is reduced and ____ is oxidized. a. NAD+ ... pyruvate b. lactate ... ethanol c. NADH ... lactate d. lactate ... NADH e. pyruvate ... NADH

e. pyruvate ... NADH The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+

In the citric acid cycle, ATP molecules are produced by _____. a. photophosphorylation b. oxidative phosphorylation c. photosynthesis d. cellular respiration e. substrate-level phosphorylation

e. substrate-level phosphorylation A phosphate group is transferred from GTP to ADP

True or False? Cellular respiration produces more lactate per mole of glucose than fermentation.

false

True or False? Cellular respiration produces more pyruvate per mole of glucose than fermentation.

false

Time sequence of four processes of cellular respiration

glycolysis -> pyruvate processing -> citric acid cycle

Cellular respiration only

pyruvate is oxidized

Fermentation only

pyruvate is reduced

True or False? Cellular respiration produces more ATP per mole of glucose than fermentation.

true

True or False? Cellular respiration produces more CO2 per mole of glucose than fermentation.

true

True or False? Cellular respiration produces more NADH per mole of glucose than fermentation.

true