hw 5

Under anaerobic conditions, NADH produced by glycolysis is recycled by a reaction that produces NAD + and A. pyruvate. B. ethanol or lactate. C. ethanol. D. lactate

B. ethanol or lactate.

How many carbons from 13 original glucose molecules enter the Krebs cycle in the absence of oxygen? A. 0 B. 26 C. 52 D. 78

A. 0

Glycolysis yields a net gain of _______ ATP molecules per molecule of glucose. A. 2 B. 36 C. 32 D. 4

A. 2

Coenzyme Q carries electrons from complex _______ to complex _______. A. I; III B. I; II C. II; III D. III; IV

A. I; III

Which of the following is a product of glycolysis that is transported into the mitochondria? A. Pyruvate B. Lactic acid C. Ethanol D. Acetate as acetyl CoA

A. Pyruvate

A stronger oxidizing agent exhibits ___________. A. greater electron affinity B. lower electron affinity C. lower oxygen-binding affinity D. greater oxygen-binding ability

A. greater electron affinity

Protons are freely permeable across A. the outer, but not the inner, mitochondrial membrane. B. neither mitochondrial membrane. C. the inner, but not the outer, mitochondrial membrane. D. both mitochondrial membranes.

A. the outer, but not the inner, mitochondrial membrane.

The role of cytochrome c in the electron transport chain is to A. transfer electrons from complex III to complex IV. B. couple the passage of protons down the gradient to ATP production. C. transfer the electrons to molecular oxygen. D. transfer electrons from complex I to complex III.

A. transfer electrons from complex III to complex IV (Cytochrome c is a peripheral inner-membrane protein that receives electrons from cytochrome b in complex III and transfers them to complex IV)

Fatty acids are broken down in a stepwise process, _______ carbon(s) at a time. A. two B. one C. four D. six

A. two

NADH produced in glycolysis yields fewer ATP molecules than that produced in the citric acid cycle because A. ATP molecules are hydrolyzed to transport the NADH across the mitochondrial inner membrane. B. its electrons are shuttled across the mitochondrial inner membrane to complex II. C. it must be converted to FADH2 for transport into the mitochondrial matrix. D. its electrons are donated to complex I on the cytoplasmic side, so it pumps no protons out of the matrix.

B. its electrons are shuttled across the mitochondrial inner membrane to complex II (Since electrons are donated to complex II, no protons are pumped out of the matrix by complex I, and fewer ATP molecules are made)

The ATP synthases of mitochondria and chloroplasts are examples of _______ proteins in which polypeptide rotation provides a mechanical coupling to ATP synthesis. A. Na+-K+ ATPase B. motor C. symport D. proton pump

B. motor (Rotation of the polypeptide, a property of a motor protein, leads to mechanical coupling necessary for ATP synthesis)

Under aerobic conditions, the NADH formed during glycolysis A. converts acetaldehyde to ethanol and hence serves as the basis of many fermentation processes. B. provides additional energy by donating its electrons to the electron transport chain. C. is a waste product of glycolysis. D. has no metabolic advantage to the cell.

B. provides additional energy by donating its electrons to the electron transport chain (Under aerobic conditions NADH can donate electrons to the electron transport chain and additional ATP can be generated.)

Together, glycolysis and the citric acid cycle (also known as the Krebs cycle) directly generate two molecules of ATP and two molecules of GTP. Most of the energy derived from the oxidation of glucose comes from the oxidation of the _______ generated from _______. A. NADH; glycolysis B. NADPH; the citric acid cycle C. NADH; the citric acid cycle D. FADH2; the citric acid cycle

C. NADH; the citric acid cycle (Six molecules of NADH are generated from the citric acid cycle, four more than from glycolysis. Eighteen molecules of ATP are formed from the oxidation of NADH through the electron transport chain)

The citric acid cycle consists of the oxidation of _______ to produce _______. A. pyruvate; CO2, NADH, and FADH2 B. acetate; CO2 C. acetyl CoA; CO2, NADH, and FADH2 D. pyruvate; CO2

C. acetyl CoA; CO2, NADH, and FADH2

Under aerobic conditions, the end product of glycolysis is A. lactate. B. ethanol. C. pyruvate. D. phosphoenolpyruvate.

C. pyruvate.

When electrons from the cofactors reduced by breakdown of one glucose are transferred to oxygen in mitochondria, the process is coupled to the formation of _______ molecules of ATP. A. 22-24 B. 2 C. 10-12 D. 32-34

D. 32-34

The inner mitochondrial membrane contains proteins that A. synthesize ATP. B. pump protons. C. transport pyruvate and fatty acids. D. All of the above

D. All of the above

What is produced when the electrons leave the electron transport chain of mitochondria and bind to the final electron acceptor for that chain? A. CO B. CO2 C. O2 D. H2O

D. H2O

What happens to the carbons of pyruvate that do NOT enter the Krebs cycle? A. They are converted to carbon monoxide (CO). B. They are converted to carbohydrates. C. They are converted to ATP. D. They are converted to glucose. E. They are converted to CO2.

E. They are converted to CO2.

The direct formation of ATP by the transfer of a phosphate group from a donor molecule to ADP is called ________. A. indigenous phosphorylation B. substrate-level phosphorylation C. cyclic photophosphorylation D. noncyclic photophosphorylation E. oxidative phosphorylation

E. oxidative phosphorylation

Most of the ATP derived from the breakdown of glucose in aerobic cells is derived from glycolysis. True False

False

Most of the ATP derived from the breakdown of glucose in anaerobic cells is derived from glycolysis. True False

True