BIOL 1105 Lecture Notes - Lecture 9: Chemiosmosis, Nitrogen Fixation, Ethanol Fermentation

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magentafrog738

13 Nov 2017

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Still have about 580 kcal/mol of energy in nadh and fadh2. Nadh is used only in catabolic reactions. Series of membrane-bound protein complexes and lipid soluble electrons carriers in the mitochondrial inner membrane. Use energy harvested from the electrons to pump protons (h+) from matrix intermembrane space. Harvest energy from protons moving down the gradient to synthesize atp. Movement of 4 h+ through atp synthase powers the synthesis of atp. Number of protons results in the amount of atp. Atp and citrate inhibit a step in glycolysis. Amount of citrate produced exceeds the amount consumed. High levels of nadh inhibit pyruvate dehydrogenase. Excess nadh starts pyruvate dehydrogenase to reduce the amount of substrate entering the krebs cycle. High levels of atp inhibit citrate synthase. Respiration may be activated by high adp levels. Inorganic molecules (not o2) used as final electron acceptor. Many prokaryotes use sulfur, nitrate, co2, or even inorganic metals. Inorganic sulfate (so4) to hydrogen sulfide (h2s)

Related Questions

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

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?

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BIOL 1105 Lecture Notes - Lecture 9: Chemiosmosis, Nitrogen Fixation, Ethanol Fermentation

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