BIOC 3110 Chapter Notes - Chapter 20: Cytochrome, Joule, Intermembrane Space

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16 Oct 2016

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Electron flow occurs in 4 large protein complexes embedded in the inner mitochondrial membrane-3 of them use energy from electron flow to pump protons, then proton gradient powers synthesis of atp. Oxidative phosphorylation depends on electron transfer: electrons from nadh and fadh2 are used to reduce oxygen to water, the electron transfer potential of an electron is measured as redox potential. The electron transfer potential is converted to phosphoryl transfer potential of atp. A strong reducing agent like nadh has low affinity for electrons (therefore wants to donate them), therefore has negative reduction potential wants to reduce by giving away electrons! In contrast, the strong oxidant like o2 really wants to accept electrons, thus has high affinity for them, therefore has positive reduction potential, because it wants to be reduced. Positive reduction potential means you want to be reduced: electron flow through the etc creates proton gradient.

Related Questions

1. Oxidative Phosphorylation and the electron transport chain (ETC)

a. How are H⁺ being pumped across the inner membrane?

b. Why is the proton gradient important in oxidative phosphorylation?

c. What are the mobile carriers (ubiquinone and cytochrome c) in the ETC doing?

d. What is meant that with the subsequent proteins in the ETC, each has a greater redox potential?

e. From where are the H⁺ ions coming from which are being pumped across the inner mitochondrial eemembrane?

f. Where would the enzymes for citric acid cycle be found?

g. Where are the protein complexes for the electron transport chain found?

1. Compared to the generation of ATP by oxidative phosphorylation, what is a major difference in mechanism of ATP generation by substrate-level phosphorylation in glycolysis?

A. A proton gradient is not involved

B. The ATP produced has less energy content because oxygen was not involved.

C. Substrate level phosphorylation occurs in the inter-mitochondrial space

D. One can't generalize without knowing the substrate.

2. Which of the following statements is true?

A. Because the electrons in NADH are at a higher energy than the electrons in reduced ubiquinone, the NADH dehydrogenase complex can pump more protons than can the cytochrome b-c1 complex.

B.The pH in the mitochondrial matrix is higher than the pH in the intermembrane space.

C. The proton concentration gradient and the membrane potential across the inner mitochondrial membrane tend to work against each other in driving protons from the intermembrane space into the matrix.

D. The difference in proton concentration across the inner mitochondrial membrane has a much larger effect than the membrane potential on the total proton-motive force.

Why does an electron have lower potential energy in an H-O bondthan in an O=O bond?

H has a higher electronegativity than O.

O=O is not stable.

O=O contains a double bond.

The electrons are closer to the oxygen atom in the H-O bond.

None of the answers are correct.

How is the energy from the electron transport chain used mostdirectly?

to form the bonds of a water molecule

to pump hydrogen ions across the mitochondrial inner membraneinto the mitochondrial intermembrane space

to join ADP with a phosphate

to decompose glucose into pyruvate

to rotate ATP synthase

Which process provides the energy needed to pump protons acrossthe mitochondrial membrane during oxidative phosphorylation?

the transfer of electrons in redox reactions

the breakdown of ATP to ADP

the rotation of the ATP synthase rotor

oxidation of isocitrate

None of the answers are correct.

What causes the ATP synthase rotor to spin?

the passing of electrons through ATP synthase

the movement of protons across the mitochondrial membrane

the movement of electrons across the mitochondrial membrane

the synthesis of ATP from ADP and a phosphate group

None of the answers are correct.

What of the following generates the proton-motive force duringoxidative phosphorylation?

buildup of NADH molecules at protein complex I

movement of H⁺ ions across the mitochondrial membraneduring electron transport

rotation of the ATP synthase rotor

joining of H⁺ ions with oxygen to form water

None of the answers are correct.

Suppose a microorganism invades a cell, causing damage to ATPsynthase. How would cellular respiration be affected?

Electrons could not be passed down the electron transportchain.

ADP could not be joined with a phosphate to form ATP.

Hydrogen ions could not be pumped into the mitochondrialintermembrane space.

The cell could not release any energy from the glucosemolecule.

Glucose could not be broken down into pyruvate.

Which molecules transport electrons from the citric acid cycleto the electron transport chain?

NADH and FADH₂

ATP and ADP

GTP and GDP

oxaloacetate and citric acid

None of the answers are correct.

Which type of reactions control the energy release from glucoseduring the citric acid cycle?

acid-base reactions

redox reactions

random reactions

All answers are correct.

None of the answers are correct.

What is the role of NAD⁺ in cellular respiration?

to receive electrons from the citric acid cycle and deliver themto the electron transport chain

to catalyze the synthesis of ATP from ADP

to accumulate in the mitochondrial intermembrane space tofacilitate ATP synthesis

to serve as a substrate to bind to acetyl-CoA at the beginningof the citric acid cycle

None of the answers are correct.

10.

Which molecule enters the citric acid cycle?

glucose

pyruvate

ATP

acetyl-CoA

None of the answers are correct.

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BIOC 3110 Chapter Notes - Chapter 20: Cytochrome, Joule, Intermembrane Space

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