Biochem for IU's Nerds

Which of the following is not a significant biological oxidizing agent ?

• O2

• Fe 3+

• NAD+

• FAD

The equation for the reduction of cytochrome a by cytochrome c is as follows:

Cyt a (+3) + Cyt c (+2) → Cyt a (+2) + Cyt c (+3)

Where

Cyt a (+3) + e- → Cyt a (+2), E'o = 0.27 V

Cyt c (+3) + e- → Cyt c (+2), E'o = 0.22 V

Which of the following answers complete the sentence correctly? Under standard conditions this reaction:

• involves the transfer of two electrons.

• does not alter the absorption spectra of the cytochromes.

• yields sufficient energy for ATP synthesis

• proceeds spontaneously

Which of the following statements about the generation of ATP in the electron transport chains is correct?

• The F1 subunit of the ATP synthase contains the motor which is driven to rotate by the proton flow.

• The F1 subunit of the ATP synthase contains the catalytic centre that synthesizes ATP.

• The F0 subunit of the ATP synthase binds ADP and Pi tightly before ATP synthesis occurs.

• The F0 subunit of the ATP synthase contains the catalytic centre that synthesizes ATP.

Coenzyme Q is involved in electron transport

• as a lipid-soluble electron carrier.

• as a water-soluble electron donor.

• as a covalently attached cytochrome cofactor.

• direct to O2.

• as a water soluble electron acceptor.

Which of the following answers completes the sentence more correctly? The rate of flow of electrons through the electron transport chain is most directly regulated by

• the concentration of acetyl CoA.

• feedback inhibition by H2O.

• the ATP : ADP ratio.

• the rate of oxidative phosphorylation.

• the catalytic rate of cytochrome oxidase.

Which molecule below has the highest affinity for electrons?

• FMN

• NAD+

• H2O

• FAD

• O2

Which statement about the chemiosmotic theory is CORRECT

• Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.

• It predicts that oxidative phosphorylation can occur, even without an intact inner mitochondrial membrane.

• The effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes.

• The membrane ATP synthase has no significant role in the chemiosmotic theory.

• All of the statements are correct.

Which statement about the chemiosmotic theory is FALSE?

• Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.

• Energy is conserved as a transmembrane pH gradient.

• Oxidative phosphorylation cannot occur in membrane-free preparations.

• The effect of uncoupling reagents is a consequence of their ability to carry protons through membranes.

• The membrane ATPase, which plays an important role in other hypotheses for energy coupling, has no significant role in the chemiosmotic theory.

In a eukaryotic cell, most of the enzymes of the Krebs cycle are located in the

• intermembrane space

• mitochondrial matrix

• inner mitochondrial membrane

• plasma membrane

Which of the following statements about the electron transport chain is correct ?

• The electron transport chain is made up of a chain of electron carriers with decreasing electron affinity.

• The electron transport chain is made up of a chain of electron carriers with increasing redox potential.

• The electron transport chain is made up of a chain of electron carriers with decreasing oxidizing power.

• The electrons transferred from carrier to carrier in the electron transport chain gain energy.