CHAPTER 9

ATP hydrolysis is an exergonic reaction while the synthesis of ATP requires the input of energy. What is the direct source of energy that is used for the synthesis of ATP during oxidative phosphorylation? A. The movement of ions down their concentration gradient. B. The exergonic release of energy from the electron transport chain. C. The oxidation of a molecule of glucose. D. The oxidation of a molecule of acetyl CoA in the TCA cycle.

A

The electron transport chain of cellular respiration is located in which part of the mitochondrion. A. Inner mitochondrial membrane B. Outer membrane C. Matrix D. Intermembrane space

A

When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________. A. reduced, and energy is released B. reduced, and energy is used C. oxidized, and energy is used D. oxidized, and energy is released

A

Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration? A. glucose → NADH → electron transport chain → oxygen B. glucose → pyruvate → ATP → oxygen C. glucose → pyruvate → electron transport chain → NADH → ATP D. food → glycolysis → citric acid cycle → NADH → ATP

A

Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate? A. ATP B. acetyl CoA C. citrate D. water

B

Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability? A. citric acid cycle B. glycolysis C. lactate fermentation D. oxidative phosphorylation

B

Which of the following processes is driven by chemiosmosis? A. substrate-level phosphorylation B. oxidative phosphorylation C. ATP hydrolysis D. reduction of NAD+ to NADH

B

5. Which of the following molecules is not a net or overall product (output) of Glycolysis? A. Pyruvate B. ATP C. Water D. NADH

C

Approximately how many molecules of ATP are produced from the complete oxidation of 1 molecule of glucose in cellular respiration? A. 1 million B. 1000 C. 30 D. 1

C

The energy released by the electron transport chain is directly used to do which of the following: A. Reduce CO2 to H2O B. To synthesize ATP from ADP and phosphate C. To transport hydrogen ions across the inner membrane of the mitochondria D. To oxidize glucose and transfer electrons to NADH

C

When Triglycerides (fats) are digested, the fatty acids are broken down into 2 carbon molecules that enter which stage of respiration? A. Glycolysis B. Electron transport C. Citric Acid Cycle D. Oxidative Phosphorylation

C

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains an electron (by the addition of a H atom), the molecule becomes _____. A. Dehydrogenated B. Oxidized C. Reduced D. Redoxed

C

Where does Glycolysis occur in the cell? A. Chloroplasts B. Lysosome C. Cytoplasm D. Mitochondria E. Nucleus

C

Which of the following events takes place in the electron transport chain? A. the breakdown of glucose into six carbon dioxide molecules B. the breakdown of an acetyl group to carbon dioxide C. the harnessing of energy from redox reactions to generate a proton gradient D. substrate-level phosphorylation

C

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy 1. The reaction above represents which metabolic process in cells?

Cellular Respiration

The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes? A. active transport B. allosteric regulation C. a reaction with a positive ΔG D. coupling of an endergonic reaction to an exergonic reaction

D

Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules? A. acetyl-CoA B. ATP C. CO2 D. NADH

D

What types of cells carry out ATP synthesis by chemiosmosis? A. all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor B. only animal cells in mitochondria, exclusively using oxygen as the electron acceptor C. only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors D. all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

D

Which of the following statements best describes the primary role played by oxygen in cellular respiration? A. It yields energy in the form of ATP as it is passed down the electron transport chain. B. It oxidizes glucose to form two molecules of pyruvate. C. It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. D. It serves as the final acceptor for electrons from the electron transport chain.

D

What are the energy investment and energy payoff phases of glycolysis?

FOR THE ENERGY INVESTMENT PHASE TWO MOLECULES OF ATP MUST BE USED (HYRDOLYZED) IN ORDER TO MAKE THE STARTING MOLECULE (GLUCOSE) HIGHLY UNSTABLE SO THAT THE FORMATION OF 2 3 CARBON MOLECULES IS SPONTANEOUS. IN THE ENERGY PAYOFF PHASE, THE TWO 3 CARBON MOLECULES ARE USED TO PRODUCE 4 ATP MOLECULES BY SUBSTRATE PHOSPHORYLATION. 2 NADH MOLECULES ARE ALSO PRODUCED. THE NET GAIN OF ATP IS 2 SINCE 4 ATP ARE MADE IN THE PAYOFF PHASE AND 2 ARE USED IN THE INVESTMENT PHASE.

The final acceptor of electrons in the electron transport chain is

OXYGEN

What happens to the pyruvate molecules produced from glycolysis, prior to entering the Citric Acid (TCA) cycle?

THE 3 CARBON PYRUVATE MOLECULES ARE OXIDIZED WHICH RESULTS IN THE PRODUCTION OF A MOLECULE OF CO2. THE ELECTRONS FROM PYRUVATE ARE TRANSFERRED TO NAD+ FORMING NADH. THE REMAINING 2 CARBON MOLECULE IS JOINED TO A MOLECULE OF COENZYME A TO PRODUCE ACETYL CO-A WHICH IS THE MOLECULE THAT ENTERS THE CITRIC ACID CYCLE.

The CO2 that results from the breakdown (catabolism) of glucose is released during what step of cellular respiration?

THE CITRIC ACID CYCLE (& PYRUVATE OXIDATION)

Why are more ATP molecules produced during oxidative phosphorylation than in either glycolysis or the citric acid cycle?

THIS IS BECAUSE THE NADH MOLECULES GENERATED IN GLYCOLYSIS, PYRUVATE OXIDATION AND CITRIC ACID CYCLE, DONATE ELECTRONS TO THE ELCTRON TRANSPORT CHAIN. THE ENERGY GENERATED FROM THE ELECTRON TRANSPORT CHAIN IS USED TO DRIVE THE SYNTHESIS OF MOST OF THE ATP THAT IS MADE IN CELLULAR RESPIRATION.

What are the 3 stages of Cellular respiration? What is the primary function of each and where does each process occur in the cell

(1) GLYCOLYSIS (2) CITRIC ACID CYCLE (& PYRUVATE OXIDATION which occurs first) (3) OXIDATIVE PHOSPHORYLATION

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (A) Which reactant is oxidized? (B) Which reactant is reduced? (C) What is the oxidizing agent and reducing agent for this reaction?

A) GLUCOSE B)OXYGEN C)GLUCOSE IS THE REDUCING AGENTOXYGEN IS THE OXIDIZING AGENT

Glycolysis results in the net production of which of the following sets of molecules per glucose molecule? 2 NAD+, 2 pyruvate, and 2 ATP 2 NADH, 2 pyruvate, and 2 ATP 4 NADH, 2 pyruvate, and 4 ATP 6 CO2, 2 pyruvate, and 2 ATP

B

What molecules regulate (ie. increase/decrease) cell respiration when the cell has a surplus or deficit of ATP?

If the cell has sufficient ATP then feedback inhibition occurs whereby the accumulated ATP inhibits an early step in glycolysis by allosterically regulating an enzyme. This is critical to prevent the cell from expending nutrients when the amount of ATP is sufficient. If the cell is expending ATP rapidly then cell respiration has to be increased. In periods of energy deficit, AMP (Adenosine Monophosphate) will accumulate. The AMP is an allosteric activator of an enzyme at an early stage of Glycolysis and will increase the rate of cellular respiration.

When oxygen levels are low, some cells will produce ATP only from Glycolysis by fermentation. What is the key step in fermentation that allows cells to continuously synthesize ATP from glycolysis?

In order to continuously supply ATP from Glycolysis, the NADH must be oxidized in order to regenerate NAD+. The NADH is oxidized and the electron are donated to pyruvate in lactose fermentation (or a 2C molecule derived from pyruvate in alcohol fermentation). The regenerated NAD+ allows Glycolysis to be repeated over and over.

What is the primary electron carrier in cellular respiration. What are the oxidized and reduced forms of this coenzyme?

NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD). THE OXIDIZED FORM IS NAD+ AND CARRIES A POSITIVE CHARGE. NAD+ CAN BE REDUCED BY ACCEPTING ELECTRONS (CARRIED BY ATOMS OF HYDROGEN) TO PRODUCE NADH. A GOOD WAY TO REMEMBER THIS IS THAT A MOLECULE THAT IS REDUCED GAINS ELECTRONS (REDUCES THE ELECTRICAL CHARGE) AND WHEN NAD+ IS REDUCED, THE GAINED ELECTRON RESULTS IN A MOLECULE OF NADH WITH A NEUTRAL (ZERO) ELECTRICAL CHARGE.

How do Proteins and Fats feed into cell respiration?

Other food sources in addition to carbohydrates can be utilized by cells. Proteins are broken down into amino acids. The amino acids can be chemically changed to intermediates that can enter respiration at several points (mostly in the citric acid cycle) of the cellular respiration pathway. An important first step is that the amino group (containing nitrogen) is removed from the amino acid. Fats primarily contribute to respiration by feeding 2 carbon molecules (ie. acetyl Co-A) into the citric acid cycle. Fatty acids are removed from glycerol (which also feeds into respiration in glycolysis) and the hydrocarbon chains are broken down (in an oxidation reaction) two carbon fragments at a time. Fats (ie. triacylglycerols) are more efficient stores of energy than carbohydrates.