Electron Transport Chain and Oxidative Phosphorylation

Questions and Answers

What is the primary function of the electron transport chain?

To oxidize NADH and FADH2

What is the net result of oxidative phosphorylation?

The synthesis of ATP from ADP and Pi

What is the role of NADH and FADH2 in the electron transport chain?

To donate electrons to the electron transport chain

What is the byproduct of the metabolism of energy-rich molecules?

CO2 and H2O Signup and view all the answers

What is the location of the enzymes responsible for electron transport and oxidative phosphorylation?

In the mitochondria Signup and view all the answers

What is the term for the process by which ATP is synthesized from ADP and Pi?

Oxidative phosphorylation Signup and view all the answers

What is the energy-rich molecule that can donate a pair of electrons to the electron transport chain?

NADH Signup and view all the answers

What is the outcome of the electron transport chain?

The release of energy used for ATP synthesis Signup and view all the answers

What is the role of cytochromes in the electron transport chain?

They accept electrons and are reduced from Fe3+ to Fe2+ Signup and view all the answers

Which complex in the electron transport chain does not produce ATP?

Complex II Signup and view all the answers

What is the result of the electrochemical gradient across the inner mitochondrial membrane?

An efflux of H+ out of the mitochondrial matrix Signup and view all the answers

What is the purpose of the proton gradient in the electron transport chain?

To produce a proton motive force for ATP synthesis Signup and view all the answers

What is the byproduct of the electron transport chain that accumulates in the intermembrane space?

H+ Signup and view all the answers

What is the chemical gradient generated across the inner mitochondrial membrane?

A lower pH outside the mitochondrial membrane Signup and view all the answers

What is the electron transport chain located in?

Inner mitochondrial membrane Signup and view all the answers

What is the purpose of the ATP synthase complex?

To synthesize ATP through oxidative phosphorylation Signup and view all the answers

What are the two components of the electrochemical gradient?

Electrical gradient and chemical gradient Signup and view all the answers

Study Notes

Electron Transport Chain (ETC) and Oxidative Phosphorylation

Mitochondria contain the enzymes responsible for electron transport and oxidative phosphorylation.
Energy-rich molecules are metabolized to form CO2 and H2O, producing metabolic intermediates that donate electrons to specific coenzymes (NAD+ and FAD) to form energy-rich reduced coenzymes (NADH and FADH2).

Electron Transport Chain

Electron transport chain (ETC) or respiratory chain (RC) oxidizes NADH and FADH2, releasing energy used for ATP synthesis through oxidative phosphorylation.
The ETC consists of four electron transport complexes in the inner mitochondrial membrane:
- Complex I: NADH-CoQ reductase (produces ATP)
- Complex II: Succinate CoQ reductase (no ATP produced)
- Complex III: CoQ- Cytochrome C reductase (produces ATP)
- Complex IV: Cytochrome C oxidase (produces ATP)

Cytochromes

Cytochromes are proteins with bound heme, each with a different reduction potential.
The iron atoms in cytochromes are in Fe3+, reduced to Fe2+ when accepting electrons, and reoxidized to Fe3+ when passing electrons to the next component.

Mechanism of Oxidative Phosphorylation

During the ETC, H+ are released into the intermembrane space, creating an electrochemical gradient across the inner mitochondrial membrane.
The electrochemical gradient consists of:
- Electrical gradient (more positive charges outside the membrane)
- Chemical gradient (pH gradient, with lower pH outside the membrane)
This H+ gradient (Proton Motif Force) is used by ATP synthase complex to make ATP via oxidative phosphorylation.

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Description

This quiz covers the electron transport chain and oxidative phosphorylation, including the role of mitochondria, energy-rich molecules, and electron donation.