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Oxidative Phosphorylation and Photophosphorylation

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Questions

Question 1

According to the chemiosmotic theory as proposed by Peter Mitchell, what is considered the reservoir for energy extracted from biological oxidation reactions in mitochondria and chloroplasts?

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Question 2

Which component of the mitochondrial respiratory chain is described as a lipid-soluble benzoquinone with a long isoprenoid side chain, capable of shuttling reducing equivalents between less mobile electron carriers?

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Question 3

What is the function of Complex IV, also known as cytochrome oxidase, in the mitochondrial respiratory chain?

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Question 4

For each pair of electrons transferred from NADH through the respiratory chain to oxygen, how many protons are pumped out of the matrix by Complex I, Complex III, and Complex IV respectively?

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Question 5

What is the standard free-energy change (DG'°) for the transfer of a pair of electrons from NADH to O2, given that the standard reduction potential (E'°) for the NAD+/NADH pair is -0.320 V and for the O2/H2O pair is 0.816 V?

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Question 6

The binding-change model for ATP synthase proposed by Paul Boyer describes a rotational catalysis mechanism. What is the direct driver of the conformational changes in the beta subunits of the F1 complex?

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Question 7

What is the function of thermogenin, also known as uncoupling protein 1 (UCP1), found in the mitochondria of brown adipose tissue?

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Question 8

What is the role of cytochrome c in the process of apoptosis?

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Question 9

According to the endosymbiotic hypothesis, how did primitive eukaryotes acquire the ability to carry out oxidative phosphorylation?

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Question 10

What is the key distinction between the light-dependent reactions and the carbon-assimilation reactions in photosynthesis?

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Question 11

What is the energy, in kilojoules per einstein, of photons with a wavelength of 700 nanometers, as calculated in the worked example?

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Question 12

In the photochemical reaction center of purple bacteria, what is the 'special pair' designated (Chl)2 that is the site of the initial photochemistry?

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Question 13

In the Z scheme of photosynthesis in plants, what is the role of Photosystem II (PSII)?

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Question 14

What is the function of the oxygen-evolving complex, also known as the water-splitting complex, in photosynthesis?

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Question 15

How many protons are moved from the stroma to the thylakoid lumen for every four electrons passed from water to NADP+ in plant chloroplasts?

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Question 16

The inhibitor IF1 prevents ATP hydrolysis during hypoxia. Under what condition is IF1 inhibitory?

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Question 17

Which genetic disease is caused by a mutation in a mitochondrial gene for a subunit of Complex I, leading to bilateral loss of vision in early adulthood?

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Question 18

What is the primary function of accessory pigments like carotenoids in photosynthesis?

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Question 19

How many protons must flow inward through the F-type ATPase in yeast mitochondria to drive the synthesis of one molecule of ATP, including the transport of substrates?

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Question 20

What is the primary function of the glycerol 3-phosphate shuttle, which is active in skeletal muscle and brain?

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Question 21

What is the immediate electron donor that replaces the electron lost from P700 in Photosystem I after photoexcitation?

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Question 22

What is the key difference in the products of noncyclic versus cyclic electron flow in photophosphorylation?

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Question 23

What is the function of the enzyme superoxide dismutase in cells?

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Question 24

How many subunits of Complex IV (cytochrome oxidase) in the human mitochondrial respiratory chain are encoded by mitochondrial DNA?

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Question 25

In the Hill reaction, what did Robert Hill's experiments demonstrate about photosynthesis in isolated chloroplasts?

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Question 26

What is the primary role of the hypoxia-inducible factor (HIF-1)?

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Question 27

On the basis of the binding-change model, what are the three successive conformations that each catalytic beta subunit of ATP synthase cycles through?

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Question 28

What is the P/O ratio, defined as the ratio of ATP synthesized per 1/2 O2 reduced, when electrons enter the respiratory chain from succinate?

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Question 29

What is the effect of the drug rotenone on mitochondrial respiration?

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Question 30

In the process of state transitions in chloroplasts, what triggers the phosphorylation of LHCII and its move from association with PSII to PSI?

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Question 31

What is the primary function of the cytochrome P-450 enzymes located in the endoplasmic reticulum of hepatocytes?

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Question 32

In the absence of a proton gradient, what is the key observation about the reaction ADP + Pi <-> ATP + H2O on the surface of the F1 component of ATP synthase?

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Question 33

Heteroplasmy in mitochondrial genetics refers to which condition?

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Question 34

What is the role of the Pi-triose phosphate antiporter in the inner chloroplast membrane?

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Question 35

What is the total number of subunits in the F1 portion of mitochondrial ATP synthase?

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Question 36

Which of the following agents acts as an uncoupler of oxidative phosphorylation by functioning as a K+ ionophore?

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Question 37

What is the primary role of bacteriorhodopsin in Halobacterium salinarum?

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Question 38

How is the regulation of Complex IV in mitochondria adapted for hypoxic conditions?

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Question 39

What is the estimated free-energy change for moving one mole of protons down the electrochemical gradient in actively respiring mitochondria, given a measured change in electrical potential of 0.15 V and a pH difference of 0.75 units?

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Question 40

In the context of photorespiration, what is the oxygenase activity of rubisco?

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Question 41

Which of these complexes is NOT involved in the cyclic electron flow pathway in plant chloroplasts?

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Question 42

What is the primary factor that regulates the partitioning of glucose 6-phosphate between glycolysis and the pentose phosphate pathway in plants?

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Question 43

What is the role of the adenine nucleotide translocase in mitochondrial function?

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Question 44

How does the uncoupler 2,4-dinitrophenol (DNP) disrupt the tight coupling between electron transfer and ATP synthesis?

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Question 45

What is the predicted ATP yield per pair of electrons from FADH2 if the mitochondrial ATP synthase has 10 c subunits, as in yeast?

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Question 46

How many protein subunits does the enzyme Complex II (succinate dehydrogenase) contain?

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Question 47

Which class of cytochromes contains a heme group that is covalently attached to the protein through thioether bonds to two Cys residues?

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Question 48

What is the acceptor control of respiration?

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Question 49

In the Rieske iron-sulfur proteins, what is the unique feature of the iron atom's coordination?

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Question 50

What is the function of the enzyme ferredoxin:NADP+ oxidoreductase in plant photosynthesis?

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