Biology Electron Transport Chain Quiz

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Questions and Answers

What is the primary role of NADH dehydrogenase in the electron transport chain?

To convert ubiquinone to FMNH2

To accept protons from the mitochondrial matrix

To transfer electrons from NADH to ubiquinone (correct)

To produce ATP directly

Which of the following describes coenzyme Q?

An enzyme that catalyzes ATP formation

A lipid-soluble electron carrier with a long isoprenoid tail (correct)

A type of cytochrome involved in ATP synthesis

A proton pump embedded in the mitochondrial membrane

How does the iron in cytochromes function within the electron transport chain?

It is reversibly converted between ferric and ferrous states (correct)

It is involved in the synthesis of NADH

It catalyzes the reaction of ADP to ATP

It binds to oxygen permanently

What forms after NADH is oxidized by NADH dehydrogenase?

FMNH2 and free protons Signup and view all the answers

What component is NOT part of the electron transport chain discussed?

Complex V Signup and view all the answers

Which structure within NADH dehydrogenase is essential for transferring hydrogen atoms?

Iron-sulfur centers Signup and view all the answers

Which option accurately describes the conversion of cytochrome iron during electron transport?

It alternates between oxidized and reduced forms Signup and view all the answers

Where does coenzyme Q get its hydrogen atoms from?

From both FMNH2 and FADH2 Signup and view all the answers

Which enzyme complex is directly involved in the oxidation of succinate?

Succinate dehydrogenase Signup and view all the answers

What is the primary function of cytochrome a + a3 within the electron transport chain?

To produce water as a byproduct. Signup and view all the answers

How do site-specific inhibitors affect the electron transport chain?

They block the passage of electrons. Signup and view all the answers

What occurs to electron carriers located before a site-specific inhibitor?

They become reduced. Signup and view all the answers

What type of reaction is always associated with oxidation in redox pairs?

Reduction. Signup and view all the answers

What is the role of standard reduction potential (E°) in redox pairs?

It determines the tendency to lose or gain electrons. Signup and view all the answers

Which molecule acts as an electron acceptor in the electron transport chain?

Oxygen. Signup and view all the answers

What happens to electrons as they move through the electron transport chain?

They produce free energy. Signup and view all the answers

What forms when cytochrome a + a3 reacts with molecular oxygen?

Water. Signup and view all the answers

What does NAD+ gain during a redox reaction?

Hydride ions. Signup and view all the answers

Which of the following statements about electron transport is true?

Free energy is released during the transfer of electrons. Signup and view all the answers

What is the primary function of the inner mitochondrial membrane?

Being impermeable to most ions and small molecules Signup and view all the answers

What are the structures called that increase the surface area of the inner mitochondrial membrane?

Cristae Signup and view all the answers

Which complex in the inner mitochondrial membrane catalyzes ATP synthesis?

Complex V Signup and view all the answers

What role do dehydrogenases play in the formation of NADH?

They remove two hydrogen atoms from their substrate. Signup and view all the answers

Which component is NOT part of the electron transport chain?

NAD+ Signup and view all the answers

Which redox pair has the most positive standard reduction potential (E°)?

1/2 O2/H2O Signup and view all the answers

Which protein carrier accepts electrons from electron donors in the electron transport chain?

Coenzyme Q Signup and view all the answers

What is the standard free energy change (ΔG°) when one electron is transferred from NADH to cytochrome c?

-52,580 cal/mol Signup and view all the answers

What approximately composes fifty percent of the mitochondrial matrix?

Proteins Signup and view all the answers

How many ATP can be produced from the transport of electrons from NADH to oxygen?

3 Signup and view all the answers

What are the protruding spheres attached to the inner membrane known as?

Inner membrane particles Signup and view all the answers

What does the chemiosmotic hypothesis primarily describe?

The coupling of electron transport to ATP production Signup and view all the answers

What metal is commonly involved in the electron transport chain proteins?

Iron Signup and view all the answers

Which compound is a strong reducing agent from the provided standard reduction potentials?

NAD+/NADH Signup and view all the answers

What is the Faraday constant (F) value used in calculating ΔG°?

23,062 cal/volt * mol Signup and view all the answers

What is the primary byproduct of oxygen's role in the electron transport chain?

Water Signup and view all the answers

What is formed when metabolic intermediates donate electrons to NAD+ and FAD?

NADH and FADH2 Signup and view all the answers

Where is the electron transport chain located within the mitochondrion?

Inner mitochondrial membrane Signup and view all the answers

What role does the electron transport chain play in ATP production?

Pumps protons to create a proton gradient Signup and view all the answers

Which complex in the electron transport chain accepts electrons from NADH?

Complex I Signup and view all the answers

What is the end product of the electron transport chain when electrons are transferred to oxygen?

Water Signup and view all the answers

How does the movement of electrons through the electron transport chain affect free energy?

Free energy is lost as electrons move Signup and view all the answers

What is the coupling process associated with ATP synthesis in oxidative phosphorylation?

Movement of electrons driving proton pumping Signup and view all the answers

Which component of the electron transport chain has the highest reduction potential?

Oxygen Signup and view all the answers

What is the consequence of the proton gradient created by the electron transport chain?

It drives ATP synthesis by ATP synthase Signup and view all the answers

Which of the following is not a component of the electron transport chain?

FADH2-Succinate reductase Signup and view all the answers

Study Notes

Electron Transport Chain

Complex V is not illustrated; it plays a role in ATP synthesis.
NAD+ is reduced to NADH, generating a free proton (H+) during the process.
NADH Dehydrogenase (Complex I) transfers hydrogen atoms to ubiquinone, using FMN as a coenzyme and possesses iron-sulfur centers for electron transfer.
Coenzyme Q (Ubiquinone) is a ubiquitous quinone that accepts hydrogen atoms from both NADH dehydrogenase and FADH2.
Cytochromes are components of the electron transport chain, containing heme groups with iron. They facilitate electron transfer by changing oxidation states between Fe3+ and Fe2+.
Cytochrome a + a3 is significant as it can directly interact with molecular oxygen, converting transported electrons and protons into water.
Site-Specific Inhibitors can obstruct electron flow by binding to electron transport chain components, affecting redox reactions and leading to reduced carriers upstream and oxidized carriers downstream.
Electrons are transferred from donors to acceptors, releasing free energy throughout the process. They can be carried as hydride ions to NAD+, hydrogen atoms to other coenzymes, or solely as electrons to cytochromes.

Bioenergetics and Oxidative Phosphorylation

The inner mitochondrial membrane is rich in proteins (50%), crucial for electron transport and oxidative phosphorylation.
The membrane is convoluted into structures called cristae, enhancing surface area for metabolic reactions.

Structures within the Mitochondria

ATP Synthase complexes protrude into the mitochondrial matrix, facilitating ATP synthesis.
The matrix is protein-rich, housing enzymes for metabolic pathways, including the TCA cycle, and containing NAD+, FAD, ADP, and inorganic phosphate (Pi) needed for ATP production.
Mitochondrial RNA and DNA (mtRNA and mtDNA) along with ribosomes are also present in the matrix.

Organization of the Electron Transport Chain

Comprises five enzyme complexes (I to V) embedded in the inner mitochondrial membrane.
Complexes I to IV function in electron transport, while Complex V is responsible for ATP synthesis.
Electron carriers, such as coenzyme Q and cytochrome c, shuttle electrons between complexes, maintaining a flow dictated by reduction potentials.

Reactions in the Electron Transport Chain

All chain members besides coenzyme Q are proteins functioning as enzymes, with various metal-containing cofactors (iron, copper) essential for their activity.

Formation of NADH

NAD+ is reduced to NADH via dehydrogenases that oxidize substrates by removing hydrogen atoms.

Energy Production and Electron Transport

Energy-rich substrates, such as glucose, are oxidized ultimately leading to CO2 and water production.
NADH and FADH2 donate electrons to the electron transport chain, where energy is released and partial ATP synthesis occurs via oxidative phosphorylation.

Standard Reduction Potential (E°)

Electrons flow from carriers with lower to higher reduction potentials, showcasing a defined order that enhances the efficiency of the electron transport chain.

Change in Free Energy (ΔG°)

ΔG° values correlate with E° variations, facilitating the conversion of energy from electron transport into usable chemical energy for ATP synthesis.

Standard Free Energy of ATP Hydrolysis

The hydrolysis of ATP releases -7300 cal/mol, while electron transfer from NADH yields approximately 52,580 cal, sufficient for producing multiple ATP molecules.

Oxidative Phosphorylation and Chemiosmotic Hypothesis

In oxidative phosphorylation, the transport of electrons triggers ATP synthesis indirectly by creating a proton gradient across the inner mitochondrial membrane.
The Chemiosmotic Hypothesis asserts that the free energy from electron transport is harnessed to drive ATP production through the movement of protons (H+) across membranes, coupling electron flow to ATP synthesis.

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Description

Test your knowledge on the Electron Transport Chain, focusing on the role of NADH and the enzymes involved. This quiz covers key concepts such as the function of Complex I and the transfer of protons. Enhance your understanding of mitochondrial processes.