Wize University Biology Textbook > Cellular Respiration

The Electron Transport Chain [detailed]

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.

Image illustrating The Electron Transport Chain

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

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.

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).

Complex III transfers electrons to complex IV through cytochrome C. Complex III transports 4 H+ across the membrane.

Complex IV transfers electrons to reduce ½ O2 to H2O. Complex IV transports 2 H+ across the membrane.

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)

Summary

Photo by RegisFrey / CC BY

How much ATP is produced from the oxidation of 1 molecule of glucose?

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

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

Practice: Complexes of ETC

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

I don't know

Practice: Names of Complexes

Match the full name to the ETC complex. (Even though not specified in the video lesson, the names match function)

Succinate/Q reductase

NADH-Q reductase complex

Cytochrome c oxidase

Ubiquinol/cytochrome c oxidoreductase

Complex I

Complex III

Complex II

Complex IV

I don't know

Practice: H+ Gradient

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

A) Protomotive force of H+ ions entering the mitochondrial matrix drives ATP synthesis.

B) H+ ions cause a conformational change in ATP synthase as they flow into the matrix.

C) The gradient is created by H+ ions being pumped out of the matrix due to multiple oxidative phosphorylation reactions.

D) The outer surface of the inner mitochondrial membrane will be charged.

E) The pHmatrix > pHintermembrane before ATP synthesis occurs.

I don't know

Practice: Cascade of Electrons

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

A) With the current generated by proton (H+) pumps

B) Against the current generated by proton (H+) pumps

C) By subsequently passing from a carrier with a higher affinity to one with a lower affinity for electrons

D) By subsequently passing from a carrier with a lower affinity to one with a higher affinity for electrons

E) O2 draws electrons down the chain

I don't know

Extra Practice

Letter A is pointing to the location of:

The label that points to the matrix is

What process is occurring in the D site

What would not be found along the membrane marked by A

You are testing a drug that causes the inner mitochondrial membrane to become permeable to $H^+$ . How would this drug affect mitochondrial ATP output?

Which complex in the electron transport system accepts electrons from reduced cytochrome c carriers?

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

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

Match the full name to the ETC complex. (Even though not specified in the video lesson, the names match function)

ATP Stynthase: Similar to 2014 Question 15

Which is TRUE about ATP synthase?

Using calculations, show how the P/O ratios for NADH (form the mitochondrial matrix) and NADH (from the cytosol) have different P/O ratios.

4𝑥��+ + 𝑥𝐴𝐷�� + 𝑥𝑃𝑖 → 𝑥𝐴𝑇𝑃

1/2��2 + 2��− + 2𝐻+ → 𝐻2𝑂

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.

The electron transport chain (Similar to 2018 question 48)

Which Statement is FALSE about complex I of the electron transport chain?

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

Why do the electrons form NADH pump more protons across the inner mitochondrial membrane than the electrons from FADH2?

Eletron transport chain (Similar to 2018 question 46)

What is FALSE about Coenzyme Q?

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.

Which Statement is FALSE about ATP synthesis?

What metabolic pathways generate ATP to be used during cruising activity versus burst activity?

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?

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

As we move downstream the electron transport chain, what happens?

During which of the following process is ATP produced?

Which of the following is not a common electron carrier?

Regarding electron transport, downhill electron carriers have what?

Which of the following is the highest affinity electron acceptor in the ETC?

Which of the following statements is correct?

Practice: Carrier

Which of the following is a potential pathway for electrons to travel from carrier to carrier?

In which situation would ATP production by oxidative phosphorylation only be partially inhibited?

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?

Which of the following statements is true about the hypothesized reason why eukaryotic cells are more complex than aerobic bacterial cells?

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 are shared between electron transport of cellular respiration and photosynthesis?

Which of the following situations would signal a loss of respiratory control?

Which of the following are common to all electron transport chains?

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?

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)

Mitochondrial anatomy

Letter A is pointing to the location of:

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?

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)?

Where does the oxygen come from to produce water in the ETC?

Oxygen sensitivity question

Which process(es) are not oxygen sensitive

substrate level phosphorylation

In which of the following process(es) do we see substrate level phosphorylation?

ETC question

Oxidative phosphorylation comprises of both the ETC and

What is the final electron acceptor in the ETC (during cellular respiration) is?

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

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.

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?

As electrons move through the ETC, each carrier molecule is:

As electrons are passed from a protein complex to the next, the final acceptor of the ETC (in animals) is

Which electron carrier would have the greatest negative impact on ATP production if its production was inhibited during oxidative phosphorylation?

Which complex of the electron transport chain does not directly impact the pH of the intermembrane space?

What would happen if you removed all malate a-ketogluterate antiporters from the mitochondria of a cell?

What is true about the ETC and/or the movement of protons across the inner membrane?

Complexes of ETC

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

Practice: Locations in Mitochondria

Letter A is pointing to the location of:

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?

ATP Synthase: Similar to 2014 Question 15

Which is TRUE about ATP synthase?

ATP Production

Which processes in central metabolism are able to generate ATP? Select all that apply.

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

Electron Transport Chain: Similar to 2014 Question 12

What causes electrons to be transported across the mitochondrial membrane in the electron transport chain?

Eletron transport chain (Similar to 2018 question 46)

What is FALSE about Coenzyme Q?

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

Why do the electrons form NADH pump more protons across the inner mitochondrial membrane than the electrons from FADH2?

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)

Practice: Carrier

Which of the following is a potential pathway for electrons to travel from carrier to carrier?

Practice: Complexes of ETC

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

Complexes of ETC

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

The Electron Transport Chain [detailed]

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