BMB211 Final Exam Shiwa Park PSU Exam

BMB211 Final Exam Shiwa Park PSU Exam Questions with Correct Answers Which of the following reactions of electron transport liberate enough free energy to be able to drive the phosphorylation of ATP? You may assume that all reactants and products are at standard state concentrations.(Select all that apply.)

• Two electrons are passed from two cytochrome c1 proteins to two cytochrome b proteins.
• Electrons are passed from a flavin-containing protein through an Fe-S cluster protein to coenzyme

Q.

• Electrons are passed from NADH to a flavin-containing protein.
• Two electrons are passed from two cytochrome c1 proteins to two cytochrome c proteins. -

Correct Answer Electrons are passed from a flavin-containing protein through an Fe-S cluster protein to coenzyme Q.Electrons are passed from NADH to a flavin-containing protein.How does mitochondrial structure contribute to aerobic metabolism, particularly in the integration of the citric acid cycle and electron transport?

• The multifolded nature of the mitochondrial inner membrane reduces the need for diffusion of

NADH from the citric acid cycle to the electron transport chain.

• The mitochondrion segregates the reactions of the citric acid cycle from the components of the

electron transport chain.

• The presence of two separate compartments in the mitochondrion allows electron transport

between compartments to be more efficiently coupled to NADH oxidation.

• Mitochondrial structure confines the reduced electron carriers from the citric acid cycle to the

matrix, near the respiratory complexes of the electron transport chain. - Correct Answer Mitochondrial structure confines the reduced electron carriers from the citric acid cycle to the matrix, near the respiratory complexes of the electron transport chain.WHY?The reactions of the citric acid cycle, being in the mitochondrial matrix, produce the reduced NADH and FADH2 there. The electron transport chain complexes, which are localized to the mitochondrial inner membrane, are thus in close proximity to the electron donors that supply the electrons that move down the transport chain. This makes the coupling between the citric acid cycle and the electron transport chain more efficient. 1 / 3

How does mitochondrial structure contribute to aerobic metabolism, particularly in the integration of the citric acid cycle and electron transport?The presence of two separate compartments in the mitochondrion allows electron transport between compartments to be more efficiently coupled to NADH oxidation.

• The reduced NADH and FADH2 produced in the citric acid cycle are localized close to the electron

transport chain complexes in the mitochondrial inner membrane.

• The mitochondrion segregates the reactions of the citric acid cycle from the components of the

electron transport chain.

• The multifolded nature of the mitochondrial inner membrane reduces the need for diffusion of

NADH from the citric acid cycle to the electron transport chain. - Correct Answer The reduced NADH and FADH2 produced in the citric acid cycle are localized close to the electron transport chain complexes in the mitochondrial inner membrane.WHY?The reactions of the citric acid cycle, being in the mitochondrial matrix, produce the reduced NADH and FADH2 there. The electron transport chain complexes, which are localized to the mitochondrial inner membrane, are thus in close proximity to the electron donors that supply the electrons that move down the transport chain. This makes the coupling between the citric acid cycle and the electron transport chain more efficient.Which of the following are NOT components of the respiratory chain complexes?Cytochrome c A flavoprotein Cytochrome a An Fe-S cluster protein - Correct Answer Cytochrome C WHY?Cytochrome c moves freely in the intermembrane space between complexes III and IV.The remainder of the above components are members of the electron transport complexes that are found in the mitochondrial inner membrane.Why does ATP production via oxidative phosphorylation require an intact mitochondrial membrane? 2 / 3

• Without an intact mitochondrial membrane, the membrane-bound enzymes responsible for ATP

synthesis would not be properly localized.

• The continuity of the mitochondrial membrane allows ATP to be segregated from ADP and Pi.
• The mitochondrial inner membrane allows a hydrogen ion gradient to form, and this gradient

powers ATP production.

• If the mitochondrial inner membrane was not intact, electron transport would not be able to

function. - Correct Answer The mitochondrial inner membrane allows a hydrogen ion gradient to form, and this gradient powers ATP production.WHY?Oxidative phosphorylation, which requires the movement of H+ ions across the mitochondrial inner membrane, would not function if the hydrogen ion gradient across the inner membrane collapsed.Thus, oxidative phosphorylation requires the compartmentalization provided by intact membranes Which of the following are reasons that a fatty acid is linked to coenzyme A for metabolic purposes?(Select all that apply.)

• An acyl-CoA has sufficient energy to initiate the β-oxidation process.
• The acyl-CoA complex can cross both the inner and outer mitochondrial membranes, unlike the

free fatty acid.

• The CoA of acyl-CoA is a molecular tag indicating that the acyl group is destined for oxidation.
• The thioester bond in acyl-CoA is resistant to oxidation during the β-oxidation cycle. - Correct

Answer An acyl-CoA has sufficient energy to initiate the β-oxidation process.The CoA of acyl-CoA is a molecular tag indicating that the acyl group is destined for oxidation.WHY?Acyl-CoAs are high-energy compounds. An acyl-CoA has sufficient energy to initiate the β-oxidation process. The CoA is also a tag indicating that the molecule is destined for oxidation.Calculate the ATP yield for the complete oxidation of the 20-carbon saturated fatty acid arachidic acid.(You should consider the β-oxidation steps, processing of acetyl-CoA through the citric acid cycle, and electron transport. Production of one GTP should be considered the equivalent of production of one ATP. Enter your answer to three significant figures.)

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