GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with the Electron Transport Chain
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #11 : Help With The Electron Transport Chain
Which of the following molecule(s) undergoes reduction during the electron transport chain?
NADH
Oxygen
None of these are reduced
Both of these are reduced
Oxygen
Reduction is the process of gaining electrons. In electron transport chain (ETC), electron carriers such as NADH and 
Example Question #32 : Cellular Respiration And Photosynthesis
Oligomycin is an inhibitor of ATP synthase. Which of the following will you observe in the cells of a patient taking oligomycin?
I. There will be a higher concentration of protons in the intermembrane space
II. Proton pump will no longer be functional
III. ATP production will be decreased
I and II
III only
I, II, and III
I and III
I and III
The question states that oligomycin inhibits ATP synthase. Recall that ATP synthase (found on the inner mitochondrial membrane) generates ATP by transporting protons from the intermembrane space (space between inner and outer mitochondrial membrane) into the mitochondria. Inhibiting this will prevent the transport of protons and will, subsequently, lead to a buildup of protons in the intermembrane space.
Proton pumps are also found on the inner mitochondrial membrane. They function to pump out protons from the inside of mitochondria to the intermembrane space, thereby providing the proton gradient for ATP synthase to generate ATP. Halting ATP synthase will cause proton pump to stop pumping protons into the intermembrane space (due to the increase in protons in intermembrane space).
ATP synthase is the major generator of ATP; therefore, halting ATP synthase via oligomycin will decrease the amount of ATP generated.
Example Question #12 : Help With The Electron Transport Chain
During ATP synthesis in mitochondria, protons move directly through __________.
F0 subunit of ATP synthase
Cytoplasmic cellular membrane
Ubiquinone
Outer mitochondrial membrane
F1 subunit of ATP synthase
F0 subunit of ATP synthase
The F0 subunit of ATP synthase is where protons flow through to create ATP. This mechanism involves a rotation of the subunit, producing ATP with each turn. ATP synthase is part of oxidative phosphorylation, the greatest ATP producing segment of cellular respiration.
Example Question #13 : Help With The Electron Transport Chain
You are studying three different reduction-oxidation couples in the electron transport chain. Their energies are as follows:
"A" +.02 V
"B" - .31 V
"C" - .41 V
What correctly describes the flow of electrons through these redox couples?
A, C, B
C, B, A
A, B, C
B, C, A
C, A, B
C, B, A
Electrons flow throughout the electron transport chain via redox reactions. They flow from the most negative voltage to the most positive voltage within the chain. Thus the correct flow would be from C (most negative) to B (Less negative) to A (most positive).
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All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
