Biochemistry: Electron Transport Chain Quiz

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Questions and Answers

Which of the following molecules is NOT a reduced electron carrier involved in the electron transport chain?

FADH2

NADH

ADP (correct)

ATP

Where does the electron transport chain take place within the mitochondria?

Inner mitochondrial membrane (correct)

Mitochondrial matrix

Cytoplasm

Outer mitochondrial membrane

What is the final electron acceptor in the electron transport chain?

FAD

Water

Oxygen (correct)

NAD+

Which of the following complexes is responsible for the transfer of electrons from FADH2 to Coenzyme Q (CoQ)?

Complex II (B) Signup and view all the answers

What is the main purpose of the electron transport chain?

To produce ATP (B) Signup and view all the answers

What is the relationship between the electron gradient and ATP production?

The electron gradient drives the movement of protons across the mitochondrial membrane, which is used to produce ATP by ATP synthase. (D) Signup and view all the answers

Which of the following statements about the electron transport chain is TRUE?

The electron transport chain uses energy released from electron transfer to pump protons across the mitochondrial membrane. (B) Signup and view all the answers

Which of the following components of the electron transport chain is directly involved in the transfer of electrons from Complex III to Complex IV?

Cytochrome C (B) Signup and view all the answers

What is the significance of a negative ΔG in chemical reactions?

The reaction is more likely to occur spontaneously. (B) Signup and view all the answers

What does the apostrophe in K′eq represent?

Modified standard conditions. (C) Signup and view all the answers

Which of the following statements about equilibrium constants is false?

Equilibrium constants can only be calculated at room temperature. (C) Signup and view all the answers

Which of the following metabolites has the highest equilibrium constant K′eq?

Phosphoenolpyruvate (A) Signup and view all the answers

Which reaction condition would most likely increase the equilibrium constant K′eq?

Raising the concentration of reactants. (A) Signup and view all the answers

Which of the following is NOT a stage of cellular respiration?

Calvin cycle (B) Signup and view all the answers

What role does compartmentalization play in cellular metabolism?

It prevents opposing metabolic pathways from interfering with each other. (C) Signup and view all the answers

What is the absolute temperature (T) used in the equation ΔG°′ = –RT ln K′eq?

Degrees Kelvin. (A) Signup and view all the answers

What is the primary function of the mitochondria in cellular respiration?

Krebs cycle and fatty acid oxidation (A) Signup and view all the answers

What does the equation C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy represent?

Aerobic respiration process (C) Signup and view all the answers

Which complex in the electron transport chain does not pump protons?

Complex 2 (A) Signup and view all the answers

What does the acronym OILRIG stand for in the context of redox reactions?

Oxidation Is Loss, Reduction Is Gain (A) Signup and view all the answers

What is the primary output of Complex 4 in the electron transport chain?

H2O (C) Signup and view all the answers

What role does negative feedback play in regulating biochemical pathways?

It inhibits a pathway based on the end product. (A) Signup and view all the answers

Which of the following coenzymes is reduced during cellular respiration?

All of the above (D) Signup and view all the answers

Which of the following complexes directly utilizes NADH?

Complex 1 (A) Signup and view all the answers

What process is primarily associated with the cytosol?

Glycolysis (A) Signup and view all the answers

What is the primary function of Coenzyme Q (CoQ) in the electron transport chain?

It carries electrons between complexes. (C) Signup and view all the answers

Which metabolic fuel has the highest energy content (kcal/g)?

Fats (B) Signup and view all the answers

Which substrates are used by Complex 2 in the electron transport chain?

FADH2 and succinate (D) Signup and view all the answers

How does compartmentalization in the mitochondrion benefit metabolic reactions?

It enhances the efficiency of energy production. (A) Signup and view all the answers

What type of feedback loop is most common in physiology and biochemistry?

Negative feedback (B) Signup and view all the answers

What is produced during oxidative metabolism in the mitochondria?

ATP and heat (B) Signup and view all the answers

Which complex facilitates the transfer of electrons to cytochrome c?

Complex 3 (D) Signup and view all the answers

What role does ubiquinone play in the electron transport chain?

It accepts electrons from major mitochondrial flavoproteins. (C) Signup and view all the answers

What is the primary function of cytochrome c in the electron transport chain?

It shuttles electrons from complex III to complex IV. (D) Signup and view all the answers

Which complex is responsible for transferring electrons from NADH to coenzyme Q?

Complex I: NADH-Q Reductase (D) Signup and view all the answers

How do iron-sulfur complexes facilitate electron transport?

Through one-electron redox reactions. (D) Signup and view all the answers

In complex III, what happens to protons during the conversion of QH2 to coenzyme Q?

Four protons are ejected into the intermembrane space. (D) Signup and view all the answers

What is the final product produced when cytochrome c passes electrons to O2 in complex IV?

Water (B) Signup and view all the answers

What occurs in the process of oxidative phosphorylation?

Energy is generated by transferring electrons through protein complexes. (C) Signup and view all the answers

What does the proton gradient created during electron transport drive?

ATP synthesis via ATP synthase. (B) Signup and view all the answers

What is the role of NAD+ in metabolic processes?

It accepts electrons during oxidation. (A) Signup and view all the answers

Which reduced coenzyme is derived from niacin (vitamin B3)?

NADH (D) Signup and view all the answers

Which reaction occurs in the first stage of fuel oxidation?

Production of reduced nucleotide coenzymes (A) Signup and view all the answers

What happens during the process of using free energy from reduced coenzymes?

It is utilized to generate ATP. (C) Signup and view all the answers

What defines the reduced form of NAD+?

NADH, which has gained an electron. (A) Signup and view all the answers

What is generated in the reductive biosynthetic reactions?

NADPH (B) Signup and view all the answers

What is the primary difference between FAD and FADH2?

FAD is oxidized, FADH2 is the reduced form. (D) Signup and view all the answers

Which statement describes the catabolism stage?

It involves the synthesis of NADH from fuels. (B) Signup and view all the answers

Study Notes

Biosystems II Course Information

Course name: PHAR 3240
Instructor: Dr. Janet Lighthouse
Email: [email protected]
Office Location: WEGPHAR 336
Spring 2025 Office Hours: Mondays 12:00 PM - 1:30 PM or by appointment in Calendly

Course Overview Weeks 1-4

Week 1: Introduction to aerobic metabolism, electron transport chain
Week 1-2: Carbohydrate metabolism (glycolysis, TCA/Krebs cycle, glycogenesis, glycogenolysis, gluconeogenesis)
Week 2-3: Lipid metabolism
Week 4: Nitrogen metabolism

Energy Generation Location

Mitochondria

Most ATP Production Step

Electron transport chain

Aerobic vs. Anaerobic Respiration

Aerobic respiration uses oxygen as the final electron acceptor.
Aerobic respiration includes glycolysis, Krebs/TCA cycle, and electron transport chain.
Anaerobic respiration uses a different final electron acceptor.
Anaerobic respiration may or may not include glycolysis, the Krebs/TCA cycle, and the electron transport chain.

Learning Objectives

Learn basic cellular metabolism terminology and concepts.
Describe how thermodynamics relates to cellular metabolism.
Outline the mitochondrial electron transport system, showing major electron carriers.
Explain how ubiquinone and iron-sulfur complexes participate in electron transport.
Define membrane potential and its role in ATP synthesis and thermogenesis.
Describe ATP synthase's mechanism.
Explain the role of feedback loops in regulating ATP synthesis.
Explain the role of uncoupling proteins in thermogenesis.
Describe the effects of inhibitors (rotenone, antimycin A, carbon monoxide, cyanide, and oligomycin) on oxygen uptake by mitochondria.

Vocabulary - Aerobic Metabolism

Metabolism
Anabolism
Catabolism
Endergonic reaction
Exergonic reaction
Gibbs Free Energy
Potential Energy
Glycolysis
Pyruvate oxidation
Citric Acid/TCA/Krebs Cycle
ATP synthase
Oxidative
Phosphorylation/Electron Transport Chain
Coenzyme Q10/ubiquinone
Succinate dehydrogenase
Cytochrome c
Nicotinamide adenine dinucleotide (NAD+)
Flavin adenine dinucleotide (FAD)
Flavin mononucleotide (FMN)

What is Metabolism?

Metabolism is the sum of all chemical reactions in a cell.
It involves both energy generation and the use of energy to build complex molecules.

Cells Require Energy

Energy is stored and released from chemical bonds of adenosine triphosphate (ATP).

ATP vs. Nucleotides

ATP is a specific nucleotide with three phosphate groups.
DNA and RNA nucleotides use deoxyribose and ribose sugars, respectively.
Both use adenine but differ in their attached sugar and phosphate groups.

ATP Hydrolysis

ATP hydrolysis releases energy stored in the phosphate bonds, converting ATP to ADP and releasing inorganic phosphate (Pi).
ATP hydrolysis is used to drive many cellular processes.

Metabolic Pathways (Anabolism vs. Catabolism)

Anabolism: Small molecules are assembled into larger ones, requiring energy input.
Catabolism: Large molecules are broken down into smaller ones, releasing energy.
These opposing pathways are coupled to efficiently use released energy.

Gibbs Free Energy

Gibbs free energy (ΔG) is the maximum amount of energy available to do work at a constant temperature and pressure.
ΔG = G_products – G_reactants, where G is the free energy of reactants and products.
All reactions in biological systems are considered to be reversible reactions

ΔG in Metabolism

Exergonic reactions release energy (negative ΔG).
Endergonic reactions require energy input (positive ΔG).
Coupled reactions utilize energy released from an exergonic reaction to drive an endergonic reaction.

Free Energy

Spontaneous (exergonic) reactions have negative ΔG, releasing energy.
Nonspontaneous (endergonic) reactions have positive ΔG, requiring energy input to proceed.

Equilibrium Constants

ΔG°' = -RT ln K'_eq (for pH 7)
K'_eq represents the equilibrium constant.
R is the gas constant, T is the absolute temperature in Kelvin.

Equilibrium Constants (examples)

Specific metabolites and their respective K'_eq and ΔG°' values are provided for various hydrolysis reactions.

What is the form of energy utilized by the cell?

Catabolic Reactions

Catabolic reactions are characterized by being spontaneous and exergonic.

Anabolic Reactions

Anabolic reactions require energy input and are characterized by having a positive ΔG.

Thermodynamics

Learn basic terminology and concepts central to cellular metabolism.
Describe how thermodynamics is related to cellular metabolism.

The Release of Energy (v1)

The breakdown of glucose releases energy via cellular respiration.

The Release of Energy (v2)

Glycolysis, pyruvate oxidation, and the citric acid cycle release energy that is stored in ATP and electron carriers.

Cellular Respiration

Cellular respiration uses glucose and oxygen to produce ATP and water.
It occurs in the mitochondria in multiple stages.
It uses multiple enzymes and electron carriers to perform the process.

Compartmentalization

Cellular pathways are compartmentalized into specific cellular compartments.
This allows for regulated processes and prevents interference in different processes.
Transport systems regulate the movement of materials across membranes.

Why is the Mitochondrion the "Powerhouse of the Cell"?

It's the location of ATP synthesis

Cellular Respiration (Detailed)

Aerobic respiration's four stages are described: glycolysis, pyruvate oxidation, citric acid cycle, and oxidative phosphorylation.

Oxidation and Reduction

Learn basic terminology and concepts central to cellular metabolism.
Describe how thermodynamics relates to cellular metabolism.

Oxidative Metabolism

Oxidation of metabolic fuels is crucial for life.
Most metabolic energy arises from oxidation-reduction (redox) reactions in mitochondria.
The important concepts to understand are electron transport to oxygen and oxidative phosphorylation. It also involves compartmentalization and mitochondrial structure.

OILRIG

Oxidation is loss of electrons.
Reduction is gain of electrons.

Oxidation as Energy

The energy content of fats, carbohydrates, proteins and alcohol is tabulated (kJ/g and kcal/g).

Redox Coenzymes

The coenzymes NAD+, FAD, and FMN are important electron carriers.
Electrons are transferred from carbohydrates and fats to these coenzymes.
This transfers to NADH, FADH2, and FMNH2, are important electron carriers crucial for oxidative phosphorylation in metabolic processes.

Energy Transfer

Learn basic terminology and concepts central to cellular metabolism.
Describe how thermodynamics is related to cellular metabolism.
Outline the mitochondrial electron transport system, showing major electron carriers.

Electron Carriers

Electron carriers (like NAD+ and FAD) store energy through electrons.
Follow the movement of hydrogens while acknowledging electrons lost or gained.

Fuel Oxidation

Fuel oxidation occurs in two main stages.
Stage 1 involves creating reduced nucleotide coenzymes from fuel oxidation.
Stage 2 involves using the energy from oxidation to produce ATP.

Nicotinamide

NAD+ is derived from niacin and plays a crucial role in catabolism and reductive biosynthetic processes.

Flavin

FAD is derived from riboflavin and is essential for electron transfer.

Redox Coenzymes (Detailed)

Chemical structures for NAD+, NADH, FAD, and FADH2 and FMN and FMNH2 are described.

ETC Components

Detailed description of electron transport system components and where they are involved in ETC.

Complex I: NADH-Q Reductase

NADH dehydrogenase uses FMN and Fe-S complexes.
Electrons are passed form NADH to coenzyme Q (ubiquinone) and protons are pumped from the matrix to the intermembrane space.

Complex II: Succinate-Q Reductase

Succinate-Q reductase does not pump protons.
Succinate is converted to fumarate, and coenzyme Q is reduced to QH2.

Complex III: QH2-Cytochrome c Reductase

Cytochrome c and Fe-S center are part of this complex.
It pumps protons into the intermembrane space.
Electrons are passed from QH2 to cytochrome с.

Complex IV: Cytochrome c Oxidase

Contains Cu ions and passes electrons from cytochrome c to O2.
O2 acts as the final electron acceptor, resulting in water production and proton pumping.

Chemiosmotic Model

The model describes how the electron transport chain generates a proton gradient across the inner mitochondrial membrane, driving ATP synthesis by ATP synthase.

Proton Gradient and ATP Production

Define membrane potential and its role in ATP synthesis and thermogenesis.
Describe ATP synthase's mechanism.

Proton Gradient Drives ATP Synthesis

Protons pumped into the intermembrane space create a gradient. This can be used to produce ATP, via ATP synthase.

Complex V: ATP Synthase

ATP synthase synthesizes ATP from ADP and inorganic phosphate (Pi).
It uses the proton gradient across the inner mitochondrial membrane to drive ATP synthesis and joins ADP and Pi via the enzyme.

As Electrons Enter Complexes

Hydrogen ions are pumped to the intermembrane space due to electron inputs into complexes in the ETC.

Electron Transport Chain Complexes

Table showing details for each complex and if they pump protons.

Which of the following are produced by the electron transport chain?

ATP
Water

Location of Hydrogen Ion Concentration

Hydrogen ion concentration is highest in the intermembrane space of the mitochondria.

Direction of H+ Movement by ATP Synthase

ATP synthase moves H+ ions from the intermembrane space toward the mitochondrial matrix.

Feedback Mechanisms

Feedback loops are common regulation mechanisms in physiology and biochemistry.
Negative feedback involves the end product inhibiting the pathway.
Positive feedback involves the end product activating the pathway.

Regulation of Oxidative Phosphorylation

ADP is the simplest activator of respiration.
Increasing ADP increases ATP production.
When ADP is used to produce ATP—respiration rate decreases.
NADH/NAD+ ratios and ATP/ADP ratios help regulate respiration and related processes.

Oxygen Consumption in Response to ADP

Graph showing the relationship between Oxygen consumption and ADP levels. Higher ADP levels increase oxygen consumption.

Mini Case Study

Instructions for forming small groups to break down the mystery case of seven deaths through lab and autopsy results.

The Mystery of the Seven Deaths

A fictionalized case study that can be used for investigation.

Background

Description of the background of a hypothetical case of deaths with similar symptoms.

7 Victims

Descriptions of 7 victims. Symptoms and how they were found.

Symptoms

Symptoms experienced by the victims. (e.g., dizziness, confusion, headache, shortness of breath, vomiting).

Autopsy Results

Results from the autopsy of the victims and normal controls. Results reveal massive cell death and mitochondrial damage and hypoxia is listed as the immediate cause of death. Normal O2 levels in blood.

Laboratory Analysis (Part 1)

Key metabolite levels were compared between normal and victim levels. ATP levels were very low and other metabolite levels were normal.

Question Set 1

Questions about the values in the chart, the different locations in respiration of NAD+/NADH production/use. Which step is most likely to be affected.

Laboratory Analysis (Part 2)

All victims tested positive for cyanide, which inhibits cytochrome c oxidase.

Question Set 2

Questions about the relationship of cyanide to cytochrome c oxidase function and the relationship between different metabolite levels (NAD+ and NADH) in the victims.

Conclusion

Summary of the case study.

Disruption of Oxidative Phosphorylation

Explain the role of uncoupling proteins in thermogenesis.
Describe the effects of inhibitors (rotenone, antimycin A, carbon monoxide, cyanide, and oligomycin) on oxygen uptake by mitochondria.

Uncouplers

Molecules/drugs that disrupt the proton gradient. This leads to loss of ATP production. They are typically hydrophobic and weak acids or bases.

Uncoupling Proteins (UCP)

Endogenous proteins found in brown adipose tissue.
They allow protons to transport outside the ETC without producing ATP.

Inhibitors of Oxidative Metabolism

Rotenone inhibits complex I.
Antimycin A inhibits complex III.
Cyanide and carbon monoxide inhibit complex IV (cytochrome c oxidase).
Oligomycin inhibits ATP synthase.

ETC Inhibitors (Details)

Detailed diagrams showing how these inhibitors disrupt electron flow in the electron transport chain. Different locations of inhibitor effects are also discussed.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the electron transport chain and its components, including the roles of electron carriers, final electron acceptors, and the significance of the electron gradient in ATP production. This quiz covers key concepts relevant to understanding cellular respiration in biochemistry.