Biochemistry: Electron Donors & Acceptors

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Questions and Answers

What occurs during the oxidation process in redox reactions?

Production of ATP

Formation of complex molecules

Loss of electrons (correct)

Gain of electrons

In a redox reaction, the substance that gains electrons is classified as what?

Oxidizing agent (correct)

Reducing agent

Organic fuel

Electron donor

What is the term used for a chemical entity that accepts electrons from another compound?

Oxidizing agent (correct)

Catalyst

Reducing agent

Electron donor

Which of the following best defines reduction in redox reactions?

Gain of electrons Signup and view all the answers

What happens to an electron acceptor in the process of a redox reaction?

It is reduced. Signup and view all the answers

Which process occurs when organic molecules are broken down without oxygen?

Fermentation Signup and view all the answers

What kind of reaction is characterized by the transfer of electrons leading to energy release?

Redox reaction Signup and view all the answers

Which of the following statements about catabolic reactions is true?

They release energy during the breakdown of organic molecules. Signup and view all the answers

Which chemical entity acts as an electron donor in oxidation-reduction reactions?

Reducing agent Signup and view all the answers

What happens to a reducing agent during the oxidation-reduction reaction?

It is oxidized. Signup and view all the answers

If a carbon-containing molecule loses hydrogen atoms during a reaction, what is likely to occur?

It is oxidized. Signup and view all the answers

What does the acronym LEO stand for in the context of oxidation-reduction?

Loses Electrons Oxidized Signup and view all the answers

How can one determine if a carbon-containing molecule has been reduced?

If it has gained hydrogen atoms. Signup and view all the answers

In a redox reaction, what is the role of oxygen?

It is the oxidizing agent and often reduced. Signup and view all the answers

Which statement best describes how glucose behaves in a redox reaction?

It loses hydrogen and is oxidized. Signup and view all the answers

What is the role of NAD+ in cellular respiration?

It serves as an electron carrier, accepting electrons during oxidation. Signup and view all the answers

During which stage of cellular respiration is NADH predominantly produced?

Citric Acid Cycle Signup and view all the answers

What does the reduction of NAD+ to NADH involve?

Gaining of hydrogen atoms. Signup and view all the answers

What is the main function of the Electron Transport Chain (ETC) in oxidative phosphorylation?

To transport electrons, ultimately combining with oxygen to form water. Signup and view all the answers

In which part of the mitochondrion does the Citric Acid Cycle occur?

Matrix Signup and view all the answers

What drives ATP synthesis during chemiosmosis?

The energy released from redox reactions of the electron transport chain. Signup and view all the answers

Which statement about oxidation-reduction reactions in cellular respiration is true?

Hydrogen is lost in oxidation and gained in reduction. Signup and view all the answers

What is the final product of the electrons from the electron transport chain?

Water Signup and view all the answers

Study Notes

Electron Donors & Acceptors

Electron donors donate electrons to another compound and are oxidized in the process.
Electron acceptors accept electrons and are reduced in the process.
Examples of electron donors include:
- Methane
- NADH
Examples of electron acceptors include:
- Oxygen
- NAD+

Oxidation and Reduction

Carbon-containing molecules that gain H atoms or lose O atoms have been reduced.
Carbon-containing molecules that lose H atoms or gain O atoms have been oxidized.
In redox reactions, the net change in electrons is zero, meaning that if one molecule is oxidized, another molecule must be reduced at the same time.

Catabolic Reactions

Complex molecules are broken down into simpler molecules, releasing energy.
Energy is released in the form of ATP and heat.
A common example is the breakdown of organic molecules (like sugars) in the presence of oxygen to produce carbon dioxide and water.

Cellular Respiration Overview

Occurs within organelles called mitochondria.
The process uses energy from organic molecules to produce ATP.
Involves the transfer of electrons from organic molecules to oxygen.

Cellular Respiration Types

Aerobic Respiration:
- Oxygen is used as an electron acceptor.
- The most common type of respiration, often referred to as "cellular respiration" itself.
Fermentation:
- Occurs without the use of oxygen.
- A partial degradation of sugars.
- An anaerobic process.

How Catabolic Reactions Produce ATP

Redox reactions (oxidation-reduction reactions) are central to energy production:
- Oxidation: Loss of electrons
- Reduction: Gain of electrons
Electron transfer during these reactions releases energy from organic molecules, which is used to make ATP.

3 Stages of Cellular Respiration

Glycolysis:
- Occurs in the cytoplasm.
- Breaks down glucose into two pyruvate molecules.
- Generates a small amount of ATP and NADH.
Citric Acid Cycle (Krebs Cycle):
- Occurs in the mitochondrial matrix.
- Oxidizes pyruvate to carbon dioxide.
- Generates more NADH and ATP.
Oxidative Phosphorylation:
- Takes place in the inner mitochondrial membrane.
- Consists of two parts:
  - Electron Transport Chain (ETC): Electrons are passed from one molecule to another, releasing energy.
  - Chemiosmosis: The energy released from the ETC is used to create a proton gradient across the inner mitochondrial membrane, which powers ATP synthesis.

Electron Carriers

NADH and FADH2 are electron carriers that play a key role in cellular respiration.
They accept electrons during oxidation reactions and transfer them to the ETC.

Summary of Cellular Respiration Stages

Glycolysis: Glucose is broken down into pyruvate (2 molecules) with a net gain of 2 ATP and 2 NADH molecules.
Citric Acid Cycle: Pyruvate is further broken down, releasing CO2, and generating 2 ATP, 6 NADH, and 2 FADH2 molecules.
Oxidative Phosphorylation: The NADH and FADH2 molecules deliver electrons to the ETC, and the energy released from electron transport is used to power ATP synthesis.
Total ATP Yield: Around 30-38 ATP molecules per glucose molecule (depending on the organism and conditions).

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Description

This quiz covers the concepts of electron donors and acceptors in redox reactions, alongside the principles of oxidation and reduction. It also explores catabolic reactions and the process of cellular respiration. Test your understanding of these fundamental biochemistry topics.