Homework 8 Flashcards
The citric acid cycle is often described as amphibolic, because ________.
it can operate both in the presence and absence of oxygen
it can oxidize both carbons and nitrogens equally well
it plays a role in both catabolism and anabolism
it is both reversible and irreversible
it plays a role in both catabolism and anabolism
The only membrane bound enzyme of the eight enzymes catalyzing reactions of the citric acid cycle is ________.
malate dehydrogenase
citrate synthase
α-ketoglutarate dehydrogenase
succinate dehydrogenase
isocitrate dehydrogenase
succinate dehydrogenase
Although the reaction in which malate is oxidized to oxaloacetate is not thermodynamically favored (∆G is close to zero), it takes place because ________.
it is coupled to ATP hydrolysis
it is coupled to a strong reduction
it is an example of anaplerotic reaction
the product is continuously used up in the next reaction which is thermodynamically favored
the product is continuously used up in the next reaction which is thermodynamically favored
Why must citrate be converted to isocitrate prior to the synthesis of α-ketoglutarate?
The enzyme that generates α-ketoglutarate cannot bind normal citrate.
Dehydrogenation of citrate does not yield NADH.
Isomerization of citrate to isocitrate is energetically favorable and drives the cycle forward.
It contains a tertiary alcohol which cannot be oxidized.
The enzyme that generates α-ketoglutarate must bind an asymmetric substrate molecule.
It contains a tertiary alcohol which cannot be oxidized.
Why is the citric acid cycle considered to be part of aerobic metabolism even though oxygen does not explicitly appear in any reaction?
Because it produces reduced electron carriers, which are re-oxidized by transferring their electrons ultimately to oxygen.
Because it takes place in the mitochondrion.
Because it contains oxidation reactions.
Because it produces carbon dioxide.
Because NADH and FADH2 produce lots of ATP when re-oxidized.
Because it produces reduced electron carriers, which are re-oxidized by transferring their electrons ultimately to oxygen.
In the mitochondrial electron transport system, the component that delivers electrons directly to oxygen is ________.
ubiquinone
succinate dehydrogenase
cytochrome oxidase
cytochrome c
cytochrome bc1
Cytochrome Oxidase
Which of the following is the electron carrier that is reduced by complexes I and II?
NADH
ubiquinone
cytochrome c
ATP synthase
FADH2
ubiquinone
The uneven distribution of protons across the inner mitochondrial membrane is often referred to as ________.
the proton gradient force
the protonmotive force
the delta force
the chemiosmotic force
the electron transport force
the protonmotive force
The electron transport chain and the ATP synthase are effectively coupled. Which of the following statements best describes how this occurs?
ATP synthase utilizes oxidized cofactors.
Through a series of conformational changes, ATP synthase generates ATP.
The electron transport chain generates an electrochemical gradient that drives the production of ATP.
The electron transport chain re-oxidizes reduced cofactors.
The electron transport chain generates an electrochemical gradient that drives the production of ATP.
