Biology 1002B Lecture 11: Bio Lecture 11 Respiration part 2.docx

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raspberrywater-buffalo978

27 Feb 2012

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Many genes go into building this complex. 40 proteins go into assembling this complex: nadh dehydrogenase. cyt c = cytochrome c: cytochromchrom oxidase. Nadh donates the e- and shuttles all the way down to combine with oxygen to form h2o. Nadh is easily oxidized (negative redox potential) and oxygen is very electronegative and have a very positive redox potential. Proteins function by binding the cofactors to themselves, it is the co-factor that get reduced. Oxygen is the terminal electron receptor of respiration: because it is strongly electro-negative, a very good oxidizing molecule. Establishing a proton gradient across the membrane (called the proton-motive force: how much energy there is to do work, protons accumulate at the inter-membrane space, potential energy is created through this gradient. Energy of nadh is conserved into pumping proton and creating the gradient: happens at the nadh dehydrogenase, ubiquinone, cytochrome oxydase. Oxidative phosphorylation (occurs at the level of the membrane, linking the electron transport)

Related Questions

19. Which of the following is a component of Succinate dehydrogenase in Electron transport chain?

A. Niacin

B. FMN

C. FAD

D. Coenzyme Q

E. Lipoic acid

20. In electron transport the flow of electrons:

A. is bidirectional

B. goes from a high energy state to a low energy state

C. takes place in the outer mitochondrial membrane

D. are used to pump H+ into the mitochondrial matrix

21. Which of the following statements about the electron transport chain is NOT correct

A. It is located in the inner mitochondrion membrane

B. Cytochrome c accepts electrons from complex II

C. Cytochrome c oxidase (complex IV) accepts electrons from Cytochrome c

D. Complex I is called NADH dehydrogenase

E. Coenzyme Q accepts electrons from complex I and complex II

22. In the electron transport chain, the enzyme cytochrome C oxidase:

A. Uses H2O as a substrate

B. Produces HOOH as a product

C. Cannot function if oxygen is absent

D. Accepts electrons from hydrogen ions

E. Uses ADP and Pi as substrates

Can you answer the following questions:

1. Carbon monoxide is considered toxic because it acts on Complex IV. How would the addition of carbon monoxide to actively respiring mitochondria affect the relative oxidation-reduction states of all components of the electron-transport chain?

A) All four complexes would remain oxidized because they function as a multisystem complex.

B) Complexes I and III would be reduced, but complexes II and IV would be oxidized because the

electrons come from FADH2 oxidation, not NADH.

C) Complexes I, II, and III would be oxidized but Complex IV would remain reduced.

D) Complexes I, II, and III would be reduced and Complex IV would be oxidized.

E) All four complexes would remain reduced because they function as a multisystem complex.

2. Electrons are not very soluble in hydrophobic environments such as a bilipid membrane. What evidence is there that electrons move from complex to complex through the lipid membrane?

A) Cytochrome C is the electron carrier in the membrane and undergoes a head-over-heel flip to set up the proton gradient.

B) Cytochrome C is the electron carrier in the membrane and contains a cydrophoric porphyrin center.

C) CoQ is the electron carrier within the membrane and seems to be confined to the respirasome.

D) CoQ is the electron carrier within the membrane and it contains a hydrophobic porphyrin center.

E) FeS clusters are the carriers within the membrane and the electrons move from one cluster to the

next in a chain-like fashion.

3. What is the rationale for saying that âelectrons flow down the electron-transport chainâ?

A) Electrons flow from oxidized carriers to reduced carriers in discrete steps like a staircase.

B) Electrons flow from half-reactions with more positive redox potentials to more negative.

C) Electrons flow from reactions that continuously generate negative free energy values.

D) Electrons flow from the outer surface to the inner surface, a top down perception.

E) Because we think of electrons flowing like a liquid, the only direction electrons can flow is down.

Oxidative phosphorylation is the final stage of cellular respiration and the main pathway of aerobic energy generation from glucose. Which of the following statements is NOT true?

a. NADH and FADH2 are used as âinputâ into the electron transport chain

b. The electron transport chain produces a proton gradient across the inner mitochondrial membrane

c. FADH2 stores less energy than NADH

d. The electron transport chain is made up of several membrane protein complexes

e. ATP synthesis by chemiosmosis requires about 30 protons per ATP molecule

Biology 1002B Lecture 11: Bio Lecture 11 Respiration part 2.docx

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