BIOC 2580 Lecture Notes - Lecture 19: Flavin Mononucleotide, Nadh Dehydrogenase, Cytochrome C Oxidase

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1 Oct 2015

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Oxidative phosphorylation constitutes the final and 3rd stage of oxidation of carbohydrates, lipids and amino acids. During this process, energy of oxidation is used to synthesise atp. It begins with the oxidation of reduced cofactors, nadh and fadh2 by the electron transport chain. Reduced cofactors such as nadh and fadh2 are good reducing agents. Oxygen is a very good oxidizing agent - one of the strongest known to chemistry. So the oxidation of any kind of reduced carbon compound is highly favourable thermodynamically. Now we see why oxygen presented such a threat - and such an opportunity - to life on this planet, when it first began to accumulate in the atmosphere, billions of years ago, thanks to photosynthesis. The calculations show you how much energy is released by the reoxidation of. Since oxygen is such a good oxidizing agent, both reactions have very large negative gibbs free energy changes.

Related Questions

Which of the following is common to both aerobic and anaerobicmicrobes?

	Fermentation
	An electron transport chain
	Pyruvate oxidation
	Glycolysis
	All of the above

The primary purpose of catabolism is

	generation of ADP.
	generation of ATP.
	oxidation of NADH to NAD⁺.
	degradation of organic molecules.
	biosynthesis.

What is a fate of pyruvate during alcoholic fermentation byyeast?

	It is reduced to lactic acid.
	It is oxidized to form glucose and carbon dioxide
	It is cleaved to form acetylaldehyde and carbon dioxide.
	It is catabolized in glycolysis.
	It is oxidized to form lactic acid and carbon dioxide.

Electrons needed to reduce an oxidized electron acceptor areprovided by

	a) externally provided compounds such asH<sub>2</sub>, lactate or formate.
	b) an intermediate electron carrier such as NADH.
	c) 0<sub>2</sub>.
	d) Both a and b
	e) All of the above

How are aerobic respiration and anaerobic respirationsimilar?

	Both use oxygen as a terminal electron carrier.
	These are other names for glycolysis.
	Both utilize inorganic molecules as terminal electronacceptors.
	Neither receives electrons from glycolysis.
	Anaerobic respiration does not exist in microbes.

The conversion of phosphoenolpyruvic acid (PEP) topyruvate

	a) releases CO<sub>2</sub>.
	b) involves the conversion of ADP and ATP.
	c) involves substrate-level phosphorylation.
	d) Both a and b
	e) Both b and c

Which of the following is the best definition offermentation?

	The reduction of glucose to pyruvic acid
	The complete catabolism of glucose to CO₂ andH₂O
	The oxidation of a carbohydrate with organic molecules servingas electron donors and acceptors
	The production of ATP from glucose
	The production of ethanol from glucose

A reaction that yields energy has a

	positive ?G_o?.
	negative ?G_o?.
	positive ?E_o?.
	negative ?E_o?.
	negative ?H_o?.

Oxidation and reduction reactions are always coupledbecause

	a) electrons generally accompany protons.
	b) protons generally accompany protons.
	c) electrons cannot exist free in solution.
	d) Both a and b
	e) All of the above

10.

Which of the following is true of aerobic respiration?

	It involves the reduction of oxygen.
	It involves the oxidation of oxygen.
	It involves the reduction of lactic acid.
	It involves the oxidation of lactic acid.
	It does not generate ATP.

plumgnu195

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.

Question 1

Which of the following statements regarding photosynthesis and cellular respiration is true?

	A.	Photosynthesis occurs in mitochondria, and cellular respiration occurs in chloroplasts.
	B.	Photosynthesis occurs in chloroplasts, and cellular respiration occurs in mitochondria.
	C.	Photosynthesis occurs in mitochondria and in chloroplasts.

Question 2

How do cells capture the energy released by cellular respiration?

	A.	They produce glucose
	B.	The energy is coupled to oxygen
	C.	They produce ATP

Question 3

During redox reactions

	A.	the loss of electrons from one molecule is called reduction
	B.	electrons are lost from one substance and added to another substance
	C.	protons from one molecule replace the electrons lost from another molecule

Question 4

Oxidation is the ________, and reduction is the ________.

	A.	gain of oxygen; loss of oxygen
	B.	loss of electrons; gain of electrons
	C.	gain of protons; loss of protons

Question 5

During cellular respiration, NADH

	A.	delivers its electron load to the first electron carrier molecule.
	B.	is chemically converted into ATP
	C.	is the final electron acceptor

Question 6

A drug is tested in the laboratory and is found to create holes in both mitochondrial membranes. Scientists suspect that the drug will be harmful to human cells because it will inhibit

	A.	the citric acid cycle only.
	B.	glycolysis only
	C.	the citric acid cycle and oxidative phosphorylation

Question 7

Which of the following metabolic pathways is common in aerobic and anaerobic metabolism?

	A.	glycolysis
	B.	the citric acid cycle
	C.	electron transport chain

Question 8

Which of the following is a result of glycolysis?

	A.	production of CO2
	B.	a net loss of two ATPs per glucose molecule
	C.	conversion of glucose to two three-carbon compounds

BIOC 2580 Lecture Notes - Lecture 19: Flavin Mononucleotide, Nadh Dehydrogenase, Cytochrome C Oxidase

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