problem sets 27-30

The passage lists the student's calculated ∆G for photosynthesis, but does not include her calculated value for cellular respiration. What is the ∆G for cellular respiration?

-686 kcal/mol [same as photosyn, opposite sign]

How many total protons are pumped across the inner mitochondrial membrane per mitochondrial NADH molecule?

10 [complex I = 4 complex II = 0 complex III = 2 complex IV = 4]

How many total ATP molecules can be generated for each FADH2, without accounting for transport of ATP back into cytoplasm? - 2 - 2.5 - 3.3

2

How many electrons enter Complex II from complete oxidation of pyruvate?

2 [4 NADH and 1 FADH2 produced per pyruvate, only FADH2 enters complex II]

How many total ATP molecules can be generated for each NADH, without accounting for transport of ATP back into cytoplasm? - 2 - 2.5 - 3.3

3.3

How many molecules of ATP are produced per glucose molecule, assuming the Malate-Aspartate shuttle is used for cytoplasmic NADH?

32 [glycolysis: 2 NADH, 2 ATP pyruv→acetyl coA: 2 NADH CAC: 6 NADH, 2 FADH2, 2 ATP net NADH: 10 net FADH2: 2 net ATP: 4 total ATP = 10(2.5) + 2(1.5) + 4 = 32]

How many electrons enter Complex I from the complete oxidation of pyruvate?

8 [4 NADH and 1 FADH2 produced per pyruvate, only NADH enters complex I]

The experimentally determined number of c subunits in the c-ring of ATP synthase varies from 8 to 15, according to species. Consider 2 different ATP synthases, one with 9 c subunits and the other with 12. Which would you expect to have a higher ATP yield per NADH oxidized? - 9 c subunits - 12 c subunits - neither, 2.5 ATP produced per NADH oxidized

9 c subunits [less subunits require less H+ to fully rotate the ring 360º]

Based on your knowledge of the components of the electron transport chain, assign the correct values of E°´ for each component listed: A. NAD+ + H+ + 2 e- → NADH B. FAD + 2 H+ + 2 e- → FADH2 C. Q + 2 H+ + 2 e- → QH2 D. cytochrome c (+3) + e- → cytochrome c (+2) E. ½ O2 + 2 H+ + 2 e- → H2O

A. -0.32 B. -0.22 C. +0.04 D. +0.25 E. +0.82

Imagine that a toxin is introduced to the body and inhibits the establishment of the proton gradient in the intermembrane space. What would you predict would be the result? - Pyruvate would be unable to enter the Citric acid cycle - Fermentation could not occur - ATP synthase would be unable to produce ATP - Substrate-level phosphorylation would be inhibited

ATP synthase unable to produce ATP

What are the products of the CAC? - CO2, ATP, and NADPH - Pyruvate, ADP, and NADH - O2, NADH, and FADH2 - CO2, NADH, and FADH2

CO2, NADH, and FADH2

If you found an individual with a genetic mutation that resulted in six protein complexes in the electron complex chain, how might you expect the production of ATP in that individual to compare to an individual with a normal four-complex electron transport chain? - Increase - Decrease - No change - Can't determine

Can't determine

Which of these processes in aerobic respiration would not be possible in the absence of oxygen? - Glycolysis - Formation of NADH from NAD+ - The Electron Transport Chain - Substrate-level phosphorylation

ETC

Oxidative phosphorylation refers to __________. - the ETC coupled to glycolysis - the ETC coupled to ATP synthesis - the CAC coupled to ATP synthesis - beta-oxidation coupled to ATP synthesis

ETC coupled to ATP synth

A scientist is studying typical mitochondria as described in the passage. In the course of his study, he measures the generation of NADH and FADH2. What is the normal destination of NADH and FADH2? - Pyruvate dehydrogenase - The intermembrane space - Electron transport chain proteins - The mitochondrial matrix

ETC proteins

One of the main arguments in favor of the theory of endosymbiosis is that mitochondria have their own genome. Which of the following cellular structures is most likely to be coded for only by mitochondrial DNA? - Growth hormone - Electron transport chain proteins - Insulin-like growth factor 1 - Glycolytic enzymes

ETC proteins

What determines the sequence of electron carriers in the electron transport chain? - e- passed through the complexes in a manner that decreases entropy - e- passed through the complexes in order of increasing reduction potential - e- passed through the complexes in order of decreasing reduction potential

Electrons are passed through the complexes in order of increasing reduction potential.

Cyanide poisoning can be deadly. Based on the passage, what is a plausible reason for why taking barbiturates is not toxic if it also inhibits part of the electron transport chain? - FADH2 can still donate electrons at Complex II - Electrons can still flow downstream of Complex I - Cyanide inhibition of Complex IV also inhibits ATP Synthase. - NADH can still donate electrons at Complex II

FADH2 can still donate electrons at Complex II

Most of the oxygen that we take in by breathing is converted to __________. - neither water nor carbon dioxide - carbon dioxide - water - hydrogen peroxide

H2O

Cytochrome c, an essential protein of the electron transport chain, is located in the mitochondria. Please identify its specific location - Intermembrane space - Inner membrane - Matrix - Outer membrane

IMS

Which of the following areas of the mitochondria has the lowest pH? - The mitochondrial cristae - The mitochondrial matrix - The cytosol - The intermembrane space

IMS

During the electron transport, energy from ________ is used to pump hydrogen ions into the ________. - NADH; mitochondrial matrix - NADH and FADH2 ; mitochondrial matrix - NADH and FADH2 ; intermembrane space - NADH; intermembrane space

NADH and FADH2 ; intermembrane space

Why is more ATP produced per molecule of NADH than FADH2? - FADH2 donates its electrons at Complex IV - More NADH is produced in the Citric Acid Cycle than FADH2 - NADH is in its reduced form and FADH2 is in its oxidized form - NADH donates its electron at Complex I

NADH donates to complex I

Figure 1 shows O2 as a reactant in cellular respiration. What is the role of O2 in this reaction? - O2 is a product of glycolysis. - O2 is a reactant in glycolysis. - O2 serves as the final electron acceptor in the ETC - O2 is required as a reactant in the Citric Acid Cycle.

O2 is the final e- acceptor

During aerobic respiration, which of the following pathways correctly orders the process of cellular metabolism after glycolysis in eukaryotic cells? - CAC → OxPhos → Pyruvate decarboxylation - CAC → Pyruvate decarboxylation → OxPhos - Pyruvate decarboxylation → OxPhos → CAC - Pyruvate decarboxylation → CAC → OxPhos

Pyruvate decarboxylation → CAC → OxPhos

Which of the following is the ETC mobile electron carrier that is soluble in the inner membrane? - Cytochrome c - QH2 - FMN - Cytochrome c1

QH2

Transferring electrons from a strong reducing agent to a weaker reducing agent would be associated with - a negative delta G - delta G = 0 - a positive delta G

a negative delta G

A deficiency in which of the following within the mitochondrial matrix will not limit a cell's rate of oxidative phosphorylation? - O2 - FADH2 - NAD+ - A deficiency in any of these will limit the rate of oxidative phosphorylation

all limit OxPhos

Rotenone, a natural product from plants, is an insecticide that inhibits complex I of the electron transport chain. Antimycin A is an antibiotic that inhibits complex III. Assuming both compounds are equally effective at blocking their respective sites in the electron transport chain, which do you expect to be a more potent poison?

antimycin A [if complex I blocked, complex II still produces QH2 which can continue through the ETC ; blocking complex III will also effectively block complex IV]

Which ATP synthase subunit catalyzes the phosphorylation of ADP? - Gamma - c - Beta - Alpha

beta

Which ATP synthase subunit binds protons from the intermembrane space? - Gamma - c - Beta - Alpha

c

At which point do electrons of NADH enter the electron transport chain?

complex I

At which point do the electrons of FADH2 enter the electron transport chain?

complex II

Coenzyme Q carries electrons from which stages of the electron-transport chain? - Complex I only - Complex I, II and III - Complex I and II only - all four

complexes I and II

Which of the following is NOT a two-electron carrier? - NADH - Cytochrome c - FADH2 - QH2

cytochrome c

With regard to the energy production by the mitochondria discussed in the passage, what is the main factor driving ATP production at the terminal step of aerobic metabolism? - Energy from the electrochemical gradient is captured by ATP synthase - The oxidation of glucose to lactate. - The reduction of glucose to lactate. - The oxidation of glucose to pyruvate.

energy from gradient captured by ATP synthase

The primary purpose of the electron transport chain of mitochondria described in the passage is - the generation of energy to sequester protons in the intermembrane space - to synthesize ATP synthase - to carry ADP into the mitochondrial matrix - to directly phosphorylate AMP

generation of energy to sequester protons in the intermembrane space

A protonated aspartic acid is more ___________ than an unprotonated one and rotates _______ the inner mitochondrial membrane - hydrophobic, into - hydrophobic, out of - hydrophilic, into - hydrophilic, out of

hydrophobic, into [conversely, a charged Asp is hydrophilic and will want to interact with the a subunit]

Cyanide is very toxic in high enough doses because it binds irreversibly to cytochrome C. Which of the following is not an effect of cyanide's inhibition of cytochrome C? - Increased pH in the mitochondrial intermembrane space - Increased ratio of ADP:ATP - Build-up of NADH - Increase in the rate of the citric acid cycle's activity

increased CAC rate

All of the following will decrease the flow of electrons through the electron transport chain EXCEPT: - Carbon monoxide - Increased levels of ATP - Increased levels of NADH - Cyanide

increased NADH

In mammalian cells, where does the electron transport chain take place? - Outer membrane of mitochondria - Cytoplasmic membrane - Inner membrane of mitochondria - Mitochondrial matrix

inner mitochondrial membrane

Where are the reactions of oxidative phosphorylation located in the cell? - mitochondrial matrix - IMS - outer membrane - inner membrane

inner mitochondrial membrane

In humans, not all glucose that is consumed is immediately utilized. Which hormones primarily regulate the storage and utilization of glucose? - Glucocorticoids and thyroid hormone - Insulin and glucagon - Insulin and glucocorticoids - Glucagon and glucocorticoids

insulin and glucagon

In mammalian cells, where are the ATP synthase catalytic sites located? - Cytoplasmic membrane - Outer membrane of mitochondria - Mitochondrial matrix - Inner membrane of mitochondria

mitochondrial matrix [F1 of ATP synthase protrudes into the matrix]

In cellular respiration, most ATP molecules are produced by _____ - oxidative phosphorylation - photophosphorylation - cellular respiration

oxidative phosphorylation

An inhibitor of Complex II would cause all of the following EXCEPT: - A build-up of FADH2 - Impaired oxidative phosphorylation - An unchanged proton concentration in the inter-membrane space

unchanged H+ conc in the IMS

How does the change in free energy (∆G) of photosynthesis compare to the ∆G of cellular respiration? - The absolute value of ∆G of photosynthesis is equal to that of cellular respiration, but positive in photosynthesis and negative in cellular respiration. - The absolute value of ∆G of photosynthesis is equal to that of cellular respiration, but negative in photosynthesis and positive in cellular respiration. - The absolute value of ∆G of photosynthesis is greater than that of cellular respiration. - The absolute value of ∆G of photosynthesis is less than that of cellular respiration.

|∆G| of photosyn = cellular resp, but + in photosyn and - in cellular resp