Biochemistry 2280A Lecture Notes - Intermembrane Space, Atp Synthase, Electrochemical Gradient

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scarletdolphin427

30 Nov 2011

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Electron transport chain pumps protons out of the mitochondrial matrix. Intermembrane space ph ~ 7, matrix ph ~ 8; intermembrane more acidic therefore more protons. More protons in intermembrane space, they want to diffuse to lower concentration. Consequence of the fact that proteins are positive and there is no counter ion being moved across the membrane with them; accumulates a positive charge on the intermembrane space side of the inner mitochondrial membrane. Positives want to get into the more negative side membrane potential. Electrical potential contributes more strongly then the concentration difference. Chemeosmotic hypothesis: protonmotive force drives the synthesis of atp: destruction of proton gradient inhibits atp synthesis synthase. F1f0 atp: a protein complex that allows protons to flow down their electrochemical gradient. The energy from this proton movement is used to make atp; couples movement of protons to atp synthesis: atp is made in the matrix. 3b section with a subunit, allowing protons to be released into matrix.

Related Questions

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.

The free energy of ATP synthesis from ATP synthase under cellular conditions is +45 kJ/mol.

a. Where does the energy come from?

b. If the pH of the matrix is 7.84, the intermembrane space is 7.16 and the membrane potential is +/- 0.15 V at 37 C, how much energy can be produced from this gradient per mol of protons?

c. How many moles of protons moving across this gradient would be required to produce enough energy for one mole of ATP to be synthesized?

d. To generate a proton gradient the mitochondria use the energy of electron transport. How much energy is produced in the oxidation of NADH by oxygen (under standard biochemical conditions)?

e. Using the answer from b, how many moles of protons could be transported out of the matrix with this oxygen energy (d)?

f. How many moles of protons are actually transported in the oxidation of NADH theough the ETC?

bronzegoat54

2. The free energy of ATP synthesis from ATP synthase under cellular conditions is +45 kJ/mol.

a. Where does the energy come from?

b. If the pH of the matrix is 7.84, the intermembrane space is 7.16 and the membrane potential is ï±0.15 V at 37 Â°C, how much energy can be produced from this gradient per mol of protons?

c. How many moles of protons moving across this gradient would be required to produce enough energy for one mole of ATP to be synthesized?

d. To generate a proton gradient the mitochondria use the energy of electron transport. How much energy is produced in the oxidation of NADH by oxygen (under standard biochemical conditions)?

e. Using your answer from b, how many moles of protons could be transported out of the matrix with this oxidation energy (d)?

f. How many moles of protons are actually transported in the oxidation of NADH through the ETC?

magentajellyfish891

Biochemistry 2280A Lecture Notes - Intermembrane Space, Atp Synthase, Electrochemical Gradient

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