BI110 Chapter Notes - Chapter 7: Inner Mitochondrial Membrane, Electrochemical Gradient, Cellular Respiration

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maroondeer323

14 Mar 2018

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Complete oxidation of glucose in rst three stages of cellular respiration produces two kinds of reduced electron carriers (nadh and fadh2) Energy stored in them is used to synthesize atp. Energy in these electron carriers is released in a series of redox reactions occurring as electrons pass through a chain of protein complexes in imm to oxygen reduced to water. Energy released by these redox reactions is not converted directly into chemical energy of atp. Passage of electrons is coupled to transfer protons across the inner mitochondrial membrane making a concentration and charge gradient. Electrochemical gradient provides a source of potential energy then used to drive the synthesis of atp. Electrons donated by nadh and fadh2 are transported along four large protein complexes that form electron transport chain. These membrane proteins are embedded in mitochondrial inner membrane. Inner mitochondrial membrane contains one of the highest concentration of proteins found in eukaryotic membrane. Electrons enter at complex 1 or 2.

Related Questions

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

Q1:

Enzymes are essential for the conversion of organic molecules in biochemical pathways. Which of the following statements is incorrect?

Enzymes reduce the activation energy of chemical reactions.

Enzymes are catalysts and appear unchanged at the end of the reaction.

Enzymes change the equilibrium of a reaction.

Enzymes form a complex with the substrate.

Enzymes facilitate both the conversion of substrates into products and of products into substrates.

Q2:

NADH and NADPH are important energy carriers in biochemical pathways. Which of the following statements about these compounds is incorrect?

NADP+ is reduced by two electrons (involving 2 protons) from photosystem I to form NADPH + H+.

NADH is produced both during glycolysis and in the TCA cycle.

NADH feeds electrons into the respiratory chain of mitcohondria, which are ultimately used to form water.

In the absence of oxygen NADH produced during glycolysis is reoxidised by formation of lactate from pyruvate or by formation of ethanol from acetaldehyde (fermentation).

The majority of NADH produced during oxidation of glucose (in the presence of oxygen) is generated during glycolysis.

Q3:

The respiratory chain converts the reducing power of NADH into the production of ATP. Which of the following statements is incorrect?

Electrons are passed through the respiratory chain in a way to optimise the production of heat.

The complexes of the respiratory chain use the energy of redox reactions to pump protons across the inner mitochondrial membrane.

The ATP synthase uses the protonmotive force to synthesize ATP.

The principle of energy conversion by respiratory chain and ATP synthase is called âchemiosmosisâ.

The electrons from NADH are passed along the respiratory chain in a number of redox reactions mostly involving complexes

raspberrytortoise897

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.

BI110 Chapter Notes - Chapter 7: Inner Mitochondrial Membrane, Electrochemical Gradient, Cellular Respiration

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