Cellular Respiration and Energy Metabolism

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Questions and Answers

What is the primary role of ATP synthase in oxidative phosphorylation?

Degrade ADP

Catalyze proton pumping

Transport electrons

Synthesize ATP (correct)

The outer mitochondrial membrane is impermeable to ions.

False

What is the function of the electron transport chain in mitochondria?

To facilitate the flow of electrons and generate a proton gradient.

The __________ membrane bears the components of the respiratory chain and the ATP synthase.

inner Signup and view all the answers

Which of the following is NOT a component in the mitochondrial matrix?

ATP synthase Signup and view all the answers

Photophosphorylation occurs in chloroplasts.

True Signup and view all the answers

What does the selective permeability of the inner mitochondrial membrane achieve?

It segregates metabolic pathways occurring in the matrix from those in the cytosol. Signup and view all the answers

Match the following components with their corresponding functions:

Porins = Form channels in the outer membrane ATP synthase = Synthesize ATP from ADP and phosphate Electron transport chain = Facilitate electron transfer Mitochondrial matrix = House citric acid cycle enzymes Signup and view all the answers

What is the main purpose of oxidative phosphorylation?

To synthesize ATP Signup and view all the answers

Photophosphorylation occurs in mitochondria.

False Signup and view all the answers

What is the ultimate electron acceptor in photophosphorylation?

NADP Signup and view all the answers

Oxidative phosphorylation involves the reduction of O2 to ______.

H2O Signup and view all the answers

Which of the following statements is true about oxidative phosphorylation and photophosphorylation?

They have fundamentally similar mechanisms. Signup and view all the answers

Match the following processes with their descriptions:

Oxidative phosphorylation = Occurs in mitochondria and involves reduction of O2 to H2O Photophosphorylation = Occurs in chloroplasts and involves oxidation of H2O to O2 Chemiosmotic theory = Explains energy storage in transmembrane proton gradient Signup and view all the answers

Who introduced the chemiosmotic theory?

Peter Mitchell Signup and view all the answers

The flow of electrons through a chain of membrane-bound carriers conserves free energy as a transmembrane ______.

electrochemical potential Signup and view all the answers

Study Notes

Oxidative Phosphorylation and Photophosphorylation

Oxidative phosphorylation is the final stage of energy metabolism in aerobic organisms, synthesizing ATP through the oxidation of carbohydrates, fats, and amino acids.
Photophosphorylation allows photosynthetic organisms to convert sunlight into ATP, the ultimate energy source in the biosphere.
Both processes are responsible for the majority of ATP production across various organisms.

Cellular Locations

In eukaryotes, oxidative phosphorylation occurs in mitochondria, while photophosphorylation happens in chloroplasts.

Chemical Reactions

Oxidative phosphorylation reduces O2 to H2O, utilizing electrons from NADH and FADH2, independent of light conditions.
Photophosphorylation oxidizes H2O to O2, using NADP as the electron acceptor, and is entirely reliant on light energy.

Mechanistic Similarities

Mechanistically, oxidative phosphorylation and photophosphorylation share three main features:
- Both entail electron flow through a series of membrane-bound carriers.
- The free energy from this electron flow is harnessed to transport protons across a membrane, creating a proton electrochemical gradient.
- Protons flow back through specific proteins (ATP synthase), generating ATP from ADP.

Chemiosmotic Theory

Proposed by Peter Mitchell in 1961, the chemiosmotic theory suggests that proton gradients across membranes serve as energy reservoirs for ATP synthesis.
This theory has significantly influenced biological energy transduction understanding and offers insight into other processes like active transport.

Mitochondrial Structure and Function

Mitochondria have two membranes: an outer membrane permeable to small molecules and ions, and an inner membrane that is impermeable without specific transporters.
The inner membrane contains the respiratory chain and ATP synthase, while the mitochondrial matrix houses various metabolic pathways, including the citric acid cycle and fatty acid oxidation.

Historical Context

The identification of mitochondria as the site of oxidative phosphorylation by Eugene Kennedy and Albert Lehninger in 1948 ushered in a new era of research on biological energy transduction.

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Description

Explore the critical processes of oxidative phosphorylation and photophosphorylation within aerobic organisms. This quiz covers how these mechanisms are essential for the synthesis of ATP and energy production from carbohydrates, fats, and amino acids. Understanding these concepts is key to grasping energy metabolism in biological systems.