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Wize University Biology Textbook > Cellular Respiration

The Electron Transport Chain [detailed]

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The Electron Transport Chain

Glycolysis, pyruvate processing, and the citric acid cycle transferred energy from glucose to 10 NADH and 2 FADH2 and produced 4 ATP by substrate level phosphorylation.
  • The electron carriers NADH and FADH2 are then used to produce more ATP by oxidative phosphorylation by transferring electrons to the electron transport chain.
  • The electron transport chain consists of a series of 4 transmembrane complexes and a transmembrane ATP synthase.
  • The energy from NADH and FADH2 is used to transport H+ ions across the membrane to generate an electrochemical gradient.

The electron transport chain can be broken down into the following steps:

  1. NADH transfers electrons to complex I, which transports 4 H+ across the membrane. The 4 electrons (e-) are transported by coenzyme Q (CoQ) to complex III.

  1. FADH2 transfers electrons to complex II. The electrons (e-) are transported by coenzyme Q (CoQ) to complex III. (NOTE: no H+ are transported by complex II).
  1. Complex III transfers electrons to complex IV through cytochrome C. Complex III transports 4 H+ across the membrane.



  1. Complex IV transfers electrons to reduce ½ O2 to H2O. Complex IV transports 2 H+ across the membrane.
  1. The electrochemical gradient that was generated in steps 1 through 4 is used to synthesize ATP. H+ ions flow through ATP synthase to produce ATP from ADP and Pi. This is called oxidative phosphorylation.

ATP YIELD: 30 - 32 ATP per glucose (Note: 2 ATP from glycolysis + 2 from TCA cycle)

PAGE BREAK

Summary


Photo by RegisFrey / CC BY
How much ATP is produced from the oxidation of 1 molecule of glucose?




(10H+/NADH)x(1ATP/4H+)=2.5ATPperNADH(10H^+/NADH)x(1ATP/4H^+)=2.5ATPperNADH

(6H+/FADH2)x(1ATP/4H+)=1.5ATPperFADH2(6H^+/FADH_2)x(1ATP/4H^+)=1.5ATPperFADH_2




Practice: Complexes of ETC

Which complex in the electron transport system initially accepts electrons from FADH2?

Practice: Names of Complexes

Match the full name to the ETC complex. (Even though not specified in the video lesson, the names match function)
A.
Cytochrome c oxidase
B.
Ubiquinol/cytochrome c oxidoreductase
C.
Succinate/Q reductase
D.
NADH-Q reductase complex
Complex I
Complex II
Complex III
Complex IV

Practice: H+ Gradient

Which of the following is FALSE regarding the H+ gradient?

Practice: Cascade of Electrons

How do electrons cascade down the electron transport chain (ETC)?

Extra Practice
Complexes of ETC
Which complex in the electron transport system initially accepts electrons from FADH2?
Practice: Complexes of ETC
Which complex in the electron transport system initially accepts electrons from FADH2?
Practice: Carrier
Which of the following is a potential pathway for electrons to travel from carrier to carrier?
Match the full name to the ETC complex. (Even though not specified in the video lesson, the names match function)
The electron transport chain (Similar to 2018 question 48)
Which Statement is FALSE about complex I of the electron transport chain?
The electron transport chain
Why do the electrons form NADH pump more protons across the inner mitochondrial membrane than the electrons from FADH2?
Cytochrome C (Similar to 2018 question 51)
Which statement is best describes the role of cytochrome C in the electron transport chain?
Eletron transport chain (Similar to 2018 question 46)
What is FALSE about Coenzyme Q?
Electron Transport Chain: Similar to 2014 Question 12
What causes electrons to be transported across the mitochondrial membrane in the electron transport chain?
Which of the following is FALSE regarding the H+ gradient?
ATP Production
Which processes in central metabolism are able to generate ATP? Select all that apply.
ATP Synthase: Similar to 2014 Question 15
Which is TRUE about ATP synthase?
Practice: Permeability to H+
You are testing a drug that causes the inner mitochondrial membrane to become permeable to H+. How would this drug affect mitochondrial ATP output?
Practice: Locations in Mitochondria
Letter A is pointing to the location of:
Complexes of ETC
Which complex in the electron transport system initially accepts electrons from FADH2?
What is true about the ETC and/or the movement of protons across the inner membrane?
What would happen if you removed all malate a-ketogluterate antiporters from the mitochondria of a cell?
Which complex of the electron transport chain does not directly impact the pH of the intermembrane space?
Which electron carrier would have the greatest negative impact on ATP production if its production was inhibited during oxidative phosphorylation?
As electrons are passed from a protein complex to the next, the final acceptor of the ETC (in animals) is
As electrons move through the ETC, each carrier molecule is:
Let's pretend you were the found of the ETC (sending respect to Peter D. Mitchell - the real founder!). After concluding there are 4 electron accepting complexes involved, you try blocking each of them individually to find out unique characteristics about each of them. When you blocked complex lll, all ATP production stopped and the proton gradient dissipated. When you blocked complex l, the ATP production was only down regulated but it still took place. The same thing happened when you blocked complex ll. What could explain these findings?
Cyanide is known to cause extremely quick death. Its main action is on complex lV of the electron transport chain. It acts to inhibit the reduction of O2. Working backwards through the chain, indicated all the problems that make this toxin so lethal.
If QH2 donated its electrons to complex lll but then didn't move to its secondary site on complex lll, what would be the result? Select all that apply
Mitochondria: Similar to 2014 Question 13
Which statement is FALSE about the mitochondria?
Electron Transport Chain: Similar to 2014 Question 12
What causes electrons to be transported across the mitochondrial membrane in the electron transport chain?
ATP Production
Which processes in central metabolism are able to generate ATP? Select all that apply.
Using calculations, show how the P/O ratios for NADH (form the mitochondrial matrix) and NADH (from the cytosol) have different P/O ratios.
4𝑥𝐻+ + 𝑥𝐴𝐷𝑃 + 𝑥𝑃𝑖 → 𝑥𝐴𝑇𝑃
1/2𝑂2 + 2𝑒− + 2𝐻+ → 𝐻2𝑂
ATP Stynthase: Similar to 2014 Question 15
Which is TRUE about ATP synthase?
Which Statement is FALSE about ATP synthesis?
A lizard is exposed to different body temperatures by changing its environment
and its oxygen consumption recorded as follows:
Why does an increase in body temperature affect the oxygen consumption?
What is the final electron acceptor in the ETC (during cellular respiration) is?
ATP Synthase
Explain the rotor like mechanism of ATP synthase. Use drawings to show the formation of ATP and explain how many H+ are needed to synthesize one ATP molecule.
Eletron transport chain (Similar to 2018 question 46)
What is FALSE about Coenzyme Q?
The electron transport chain
Why do the electrons form NADH pump more protons across the inner mitochondrial membrane than the electrons from FADH2?
Cytochrome C (Similar to 2018 question 51)
Which statement is best describes the role of cytochrome C in the electron transport chain?
The electron transport chain (Similar to 2018 question 48)
Which Statement is FALSE about complex I of the electron transport chain?
Match the full name to the ETC complex. (Even though not specified in the video lesson, the names match function)
ETC question
Oxidative phosphorylation comprises of both the ETC and
chemiosmosis
substrate level phosphorylation
In which of the following process(es) do we see substrate level phosphorylation?
Oxygen sensitivity question
Which process(es) are not oxygen sensitive
What would not be found along the membrane marked by A
What process is occurring in the D site
Letter A is pointing to the location of:
What metabolic pathways generate ATP to be used during cruising activity versus burst activity?
Where does the oxygen come from to produce water in the ETC?
Practice: Cascade of Electrons
How do electrons cascade down the electron transport chain (ETC)?
Practice: H+ Gradient
Which of the following is FALSE regarding the H+ gradient?
Electron transport chain
You are testing a drug that causes the inner mitochondrial membrane to become permeable to H+. How would this drug affect mitochondrial ATP output?
Mitochondrial anatomy
Letter A is pointing to the location of:
Practice: Names of Complexes
Match the full name to the ETC complex. (Even though not specified in the video lesson, the names match function)
Practice: Complexes of ETC
Which complex in the electron transport system initially accepts electrons from FADH2?
Similarities between ETCs in chloroplasts and mitochondria - Practice Question
The electron transport chains in the chloroplast and the mitochondria share many similarities. Which of the following statements are true?
Which of the following are common to all electron transport chains?
Which of the following situations would signal a loss of respiratory control?
Which of the following are shared between electron transport of cellular respiration and photosynthesis?
In which of the following situations can Chlamydomonas grow?
In the presence of light, carbon dioxide and water alone
In the presence of acetate, water and oxygen alone
Which of the following statements is true about the hypothesized reason why eukaryotic cells are more complex than aerobic bacterial cells?
The given figure shows the effect of different compounds on the amount of chlorophyll in a Chlamydomonas cell, a single cells photosynthetic eukaryote. Based on the figure, which of the following statements most accurately describes what the amount of chlorophyll is indicating?
In which situation would ATP production by oxidative phosphorylation only be partially inhibited?
Practice: Carrier
Which of the following is a potential pathway for electrons to travel from carrier to carrier?
Which of the following statements is correct?
Which of the following is the highest affinity electron acceptor in the ETC?
Regarding electron transport, downhill electron carriers have what?
Which of the following is not a common electron carrier?
During which of the following process is ATP produced?
As we move downstream the electron transport chain, what happens?
How do electrons cascade down the electron transport chain (ETC)?
Which of the following is FALSE regarding the H+ gradient?
Which complex in the electron transport system initially accepts electrons from FADH2?
Which complex in the electron transport system accepts electrons from reduced cytochrome c carriers?
You are testing a drug that causes the inner mitochondrial membrane to become permeable to H+H^+. How would this drug affect mitochondrial ATP output?
The label that points to the matrix is