Oxidative Phosphorylation

1.

1 point

For eukaryotes, oxidative phosphorylation using redox energy (NADH and FADH2) occurs largely in the:

Mitochondria

Nucleus

Cytosol

Endoplasmic reticulum

2.

1 point

Which of the following statements is NOT true?

The matrix of the mitochondria contains the PDH complex, citric acid cycle enzymes, ATP, and ions.

Glycogen synthase synthesizes a glucogen chain by forming a 1>4 polyglucose chain, and adds glucose units to the chain sequentially.

Muscle glycogen can’t give rise to blood glucose, but it can power muscle contractions for extended periods of time.

The inner membrane of mitochondria contains respiratory electron carriers, ADP-ATP translocase, and ATP synthase.

3.

1 point

Oxidative phosphorylation is the process of converting:

Redox energy from glycolysis and the Krebs cycle to chemical energy, in the form of ATP.

NAD+, FAD+ and GTP from glycolysis and the Krebs cycle into ATP.

Chemical energy from glycolysis and the Cori cycle into redox energy in the form of ATP.

Chemical energy in the form of ATP from glycolysis and the Cori cycle into redox energy in the form of NADH and FADH2.

4.

1 point

The chemiosmotic model states that redox energy is converted into an electrochemical gradient, which drives the unfavourable reaction of:

4e- + ATP + Pi <> ADP + H2O

+H + ADP + Pi <> ADP + CO2

+H + ADP + Pi <> ATP + H2O

4e- + ADP + PPi <> ATP + H2O

5.

1 point

Which of the following is NOT a step of oxidative phosphorylation?

STEP 1: Electrons from NADH and/or FADH2 are transferred to complex III and complex IV respectively.

STEP 2: Electrons flow through mitochondrial membrane complexes and electron transporters of the electron transport chain.

STEP 3: Protons are pumped from the matrix to the intermembrane space using the proton pumps of complex I, III, and IV while electrons flow through the complexes.

STEP 4: Protons flow from the inner membrane space to the Fo component of ATP synthase back into the matrix. This causes the y and Fo component to rotate, and the F1 component to make ATP from ADP and Pi.

6.

1 point

The electron transport chain be described as:

The flow of electrons through complexes in the inner mitochondrial membrane and the pumping of protons from the matrix to the intermembrane space to create a proton gradient.

The flow of protons through complexes in the intermembrane space and the pumping of electrons from the matrix of the inner mitochondrial membrane to create an electron gradient.

The flow of electrons through complexes in the matrix and the pumping of protons from the intermembrane space to the inner mitochondrial membrane to create a proton gradient.

The flow of electrons through complexes in the intermembrane space and the pumping of protons from the matrix of the inner mitochondrial membrane to create a proton gradient.

7.

1 point

Complex I is an enzyme made of 42 subunits, including a flavoprotein subunit, Fe-S clusters, and an iron-sulphur protein called N-2 that electrons flow through. Which 2 simultaneous reactions does it catalyze?

The exergonic transfer of a hydride ion and 2e- from NADH and a proton from the matrix to ubiquinone. The endergonic pumping of 4 protons per NADH from the matrix to the intermembrane space, causing the intermembrane space to become positive and the matrix negative.

The endergonic transfer of a hydride ion and 2e- from NADH and a proton from the matrix to ubiquinone. The exergonic pumping of 4 protons per NADH from the matrix to the intermembrane space, causing the intermembrane space to become positive and the matrix negative.

The exergonic transfer of a proton from NADH, and a hydride ion and 2e- from the matrix to ubiquinone. The endergonic pumping of 6 protons per NADH from the matrix to the intermembrane space, causing the intermembrane space to become positive and the matrix negative.

The exergonic transfer of a hydride ion and 2e- from NADH and a proton from the matrix to ubiquinone. The endergonic pumping of 4 protons per NADH from the matrix to the intermembrane space, causing the intermembrane space to become negative and the matrix positive.

8.

1 point

What is the purpose of coenzyme Q? (Hint: Its oxidized form is called ubiquinone. When it acquires e- and becomes reduced, it is called ubiquinol.)

It is an inner mitochondrial membrane electron carrier which transfers electrons from Complex III to Complex IV.

It is an inner mitochondrial membrane proton carrier which transfers protons from Complex III to Complex IV.

It is an inner mitochondrial membrane proton carrier which transfers protons from Complex I and II to Complex III.

It is an inner mitochondrial membrane electron carrier which transfers electrons from Complex I and II to Complex III.

9.

1 point

Complex II has 4 protein subunits. Which of the following is NOT true for its subunits?

Subunits A and B contain 3 Fe-S centres, a bound FADH2, and a binding site for ubiquinone.

Subunits C and D contain a heme group (heme b) and a ubiquinone binding site.

Subunits A and B extend into the matrix.

Subunits C and D are integral membrane proteins with 3 transmembrane helices.

10.

1 point

Which of the following is NOT true for Complex II?

Complex II has a heme C group with a Fe3+ atom that is reduced after accepting an electron from Complex I.

Electron flow through Complex II is via succinate > FAD > Fe-S > Q.

Complex II is not a proton pump.

It is also known as succinate dehydrogenase from the Krebs cycle.

11.

1 point

Complex III couples the transfer of e- from ubiquinol to cytochrome C. It is a dimer where each monomer has 3 subunits. Which is not one of these subunits?

Cytochrome b, which has 2 types of heme – bH and bL.

Cytochrome a, which binds electrons.

Rieske iron-sulphor proteins (RISPS) which contain a Fe-S cluster.

Cytochrome C1.

12.

1 point

The 2 cytochrome b subunits of Complex III surround a cavern in the middle of the membrane. This allows (a) __________ to move from the matrix site of the membrane (site QN) to the intermembrane space (site QP) as it shuttles e- and H+ across the (b) ___________.

(a) fumarate (b) intermembrane space

(a) FAD (b) intermembrane space

(a) succinate (b) inner mitochondrial membrane

(a) ubiquinone (b) inner mitochondrial membrane

13.

1 point

Cytochrome C is an inner membrane space protein which:

Has a central Fe2+ atom that is oxidized after accepting a proton from Complex III, and returns to Fe2+ after donating it to Complex IV.

Contains a heme C with a central Fe3+ atom that is reduced after accepting an electron from Complex III, and returns to Fe3+ after donating it to Complex IV.

Contains a heme C with a central Fe3+ atom that is reduced after accepting an electron from Complex II, and returns to Fe3+ after donating it to Complex III.

Contains a heme B with a central Fe3+ atom that is reduced after accepting an electron from Complex III, and returns to Fe3+ after donating it to Complex IV.

14.

1 point

Which of the following statements is NOT true of oxidative phosphorylation?

NADH experiences electron transferring. This causes a proton gradient, charge differentiation, and the production of ATP.

Complex III pumps 4 protons per a NADH.

Complex IV pumps 2 protons per NADH and 4 protons per O2.

Complex IV donates electrons to O2, which is oxidized to H2O.

15.

1 point

Complex IV is made of 4 core subunits. Which is not an accurately described subunit?

Subunit I – Contains 2 heme groups and a copper ion (CuB).

Subunit II – Contains the cytochrome C binding site, and has 2 copper ions complexed to 2 cysteines.

Subunit III – Needed for rapid proton movement through Subunit II.

Subunit IV – Contains Alana Mitchell, which passes the electron onto O2.

16.

1 point

ATP synthase uses the proton gradient formed by the proton pumps to drive the synthesis of ATP. Its Fo stalk spans the inner mitochondrial membrane and is made of ‘a’, 2B2, and 10c subunits. Its F1 head is on the matrix side of the inner membrane and has 9 subunits (a3, b3, y, d, e). It has 3 nonequivalent adenine-nucleotide-binding sites, one for each alpha-beta pair. Which of the following is not one of these sites?

A site in beta-ADP conformation, which binds ADP + Pi.

A site in beta-empty conformation.

A site in beta-ATP conformation, which binds ATP tightly.

A site in beta-PPi conformation, which binds PPi.

17.

1 point

Which of the following is not true for ATP synthesis?

Proton motive force causes rotation of the y subunit of ATP synthase as protons are pumped through the F0 component.

Terry Mulhern originally invented ATP and ATP is an acronym for Adenine Terry Phosphate.

ATP synthesis results from the rotational catalysis mechanism.

Peter Mitchell was awarded a Nobel prize for his chemiosmotic model.

18.

1 point

(a) ___ ATP is produced per a NADH, and (b) ___ ATP is made per a FADH2.

(a) 2.5 (b) 1.5

(a) 4 (b) 6

(a) 3.5 (b) 1.5

(a) 3.5 (b) 4