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Questions and Answers
Fe-S clusters within proteins can carry ______ electron at a time.
Fe-S clusters within proteins can carry ______ electron at a time.
1
Haems are capable of carrying ______ electron at a time.
Haems are capable of carrying ______ electron at a time.
1
Quinones can carry ______ electrons at a time.
Quinones can carry ______ electrons at a time.
2
Cofactors in respiration have their own ______ potentials.
Cofactors in respiration have their own ______ potentials.
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The structure known as 'Complex I' is part of the ______ chain in mitochondria.
The structure known as 'Complex I' is part of the ______ chain in mitochondria.
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NADH is a key electron donor in the ______ process.
NADH is a key electron donor in the ______ process.
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In the mitochondrial matrix, fatty acids are transferred through ______.
In the mitochondrial matrix, fatty acids are transferred through ______.
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Oxygen is utilized as the final electron ______ in the electron transport chain.
Oxygen is utilized as the final electron ______ in the electron transport chain.
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The ______ is the site of ATP synthesis within the mitochondrion.
The ______ is the site of ATP synthesis within the mitochondrion.
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The ______ transport chain is responsible for transferring electrons during mitochondrial respiration.
The ______ transport chain is responsible for transferring electrons during mitochondrial respiration.
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Redox potentials measure the tendency of a substance to gain or lose ______.
Redox potentials measure the tendency of a substance to gain or lose ______.
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Mitochondrial respiration occurs in the ______ of the cell.
Mitochondrial respiration occurs in the ______ of the cell.
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______ are molecules that assist enzymes in biochemical reactions during respiration.
______ are molecules that assist enzymes in biochemical reactions during respiration.
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The proton motive force is defined as Δp (mV) = Δψ – 59(or 61)Δp______.
The proton motive force is defined as Δp (mV) = Δψ – 59(or 61)Δp______.
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In electron transport, the strongest reductants are found at the ______ of the redox potential scale.
In electron transport, the strongest reductants are found at the ______ of the redox potential scale.
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The main function of the mitochondrion is to produce ______ for the cell.
The main function of the mitochondrion is to produce ______ for the cell.
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A common electron donor in respiration is ______/NADH.
A common electron donor in respiration is ______/NADH.
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In the process of respiration, approximately ______ ATPs are produced per O2 molecule burned.
In the process of respiration, approximately ______ ATPs are produced per O2 molecule burned.
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The redox couple ½O2/H2O has a standard reduction potential of ______ volts.
The redox couple ½O2/H2O has a standard reduction potential of ______ volts.
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Flavins can carry ______ electrons at a time.
Flavins can carry ______ electrons at a time.
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Each proton releases roughly ______ kJ mol-1 of free energy.
Each proton releases roughly ______ kJ mol-1 of free energy.
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In the context of respiration, electron transfer occurs within ______ via cofactors.
In the context of respiration, electron transfer occurs within ______ via cofactors.
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For every O2 consumed, about ______ protons are pumped across the mitochondrial membrane.
For every O2 consumed, about ______ protons are pumped across the mitochondrial membrane.
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The reaction NADH + H+ + ½O2 → NAD+ + H2O has a ΔE0' of ______ volts.
The reaction NADH + H+ + ½O2 → NAD+ + H2O has a ΔE0' of ______ volts.
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The P:O ratio indicates the number of protons required to make one ______.
The P:O ratio indicates the number of protons required to make one ______.
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The process of ATP synthesis in mitochondria is linked to the flow of ______ through the inner mitochondrial membrane.
The process of ATP synthesis in mitochondria is linked to the flow of ______ through the inner mitochondrial membrane.
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The strongest oxidants are located at the ______ of the redox potential scale.
The strongest oxidants are located at the ______ of the redox potential scale.
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In the electron transport chain, SO42-/H2S has a redox potential of ______ volts.
In the electron transport chain, SO42-/H2S has a redox potential of ______ volts.
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Thermodynamically, it takes approximately ______ kJ mol-1 to synthesize ATP from ADP.
Thermodynamically, it takes approximately ______ kJ mol-1 to synthesize ATP from ADP.
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The Adenine Nucleotide Translocator (ANT) is influenced by Δ______, contributing to ATP transport.
The Adenine Nucleotide Translocator (ANT) is influenced by Δ______, contributing to ATP transport.
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The transfer of electrons in respiration is crucial for ______ synthesis.
The transfer of electrons in respiration is crucial for ______ synthesis.
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In mitochondrial respiration, the case of extra protons is due to the need to produce ATP for the ______.
In mitochondrial respiration, the case of extra protons is due to the need to produce ATP for the ______.
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______ are essential cofactors in respiration that assist in the electron transport chain.
______ are essential cofactors in respiration that assist in the electron transport chain.
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The mitochondrion creates ATP for the cell, not for its own ______.
The mitochondrion creates ATP for the cell, not for its own ______.
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The ______ is the site for electron transport in mitochondria.
The ______ is the site for electron transport in mitochondria.
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The proton gradient across the inner membrane creates a ______ that drives ATP synthesis.
The proton gradient across the inner membrane creates a ______ that drives ATP synthesis.
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Electrons are ultimately transferred to the terminal ______ in the electron transport chain.
Electrons are ultimately transferred to the terminal ______ in the electron transport chain.
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Uncoupling protein 1 (UNC1) in brown fat mitochondria plays a role in ______ thermogenesis.
Uncoupling protein 1 (UNC1) in brown fat mitochondria plays a role in ______ thermogenesis.
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Dinitrophenol (DNP) is a chemical that acts as a potent ______ of oxidative phosphorylation.
Dinitrophenol (DNP) is a chemical that acts as a potent ______ of oxidative phosphorylation.
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The transfer of electrons in the mitochondrial electron transport chain is coupled with the pumping of ______ ions.
The transfer of electrons in the mitochondrial electron transport chain is coupled with the pumping of ______ ions.
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Quinones are ______ that facilitate electron flow in mitochondrial respiration.
Quinones are ______ that facilitate electron flow in mitochondrial respiration.
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In the electron transport chain, the redox potentials of molecules determine their ability to ______ electrons.
In the electron transport chain, the redox potentials of molecules determine their ability to ______ electrons.
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The ______ region of the mitochondria is involved in ATP synthesis through the enzyme ATP synthase.
The ______ region of the mitochondria is involved in ATP synthesis through the enzyme ATP synthase.
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What is the primary function of the mitochondrion within the cell?
What is the primary function of the mitochondrion within the cell?
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Which process is directly coupled to ATP synthesis in mitochondria?
Which process is directly coupled to ATP synthesis in mitochondria?
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What is the primary role of the TCA Cycle within cellular metabolism?
What is the primary role of the TCA Cycle within cellular metabolism?
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Which component of the mitochondrion is primarily responsible for ATP synthesis?
Which component of the mitochondrion is primarily responsible for ATP synthesis?
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What is the significance of the proton motive force in mitochondria?
What is the significance of the proton motive force in mitochondria?
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What is the role of mitofusin proteins in mitochondrial biogenesis?
What is the role of mitofusin proteins in mitochondrial biogenesis?
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Which of the following best describes the mitochondrial proton electrochemical gradient?
Which of the following best describes the mitochondrial proton electrochemical gradient?
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What is the approximate size of the mitochondrial genome?
What is the approximate size of the mitochondrial genome?
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What triggers Drp1 to form a ring structure that constricts during mitochondrial division?
What triggers Drp1 to form a ring structure that constricts during mitochondrial division?
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How much free energy is generally produced from the proton gradient in the mitochondrion?
How much free energy is generally produced from the proton gradient in the mitochondrion?
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What does the equation ΔG = R × T × ln ([inside]/[outside]) represent in terms of an electrochemical gradient?
What does the equation ΔG = R × T × ln ([inside]/[outside]) represent in terms of an electrochemical gradient?
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Which constant is used in the equation for calculating the change in free energy for a proton gradient?
Which constant is used in the equation for calculating the change in free energy for a proton gradient?
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In a proton gradient, what does a ΔpH of approximately 0.5 indicate?
In a proton gradient, what does a ΔpH of approximately 0.5 indicate?
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What should be carefully considered when working through electrochemical gradient calculations?
What should be carefully considered when working through electrochemical gradient calculations?
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What effect does a positive Δψ have on the inner membrane in terms of proton movement?
What effect does a positive Δψ have on the inner membrane in terms of proton movement?
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What is the significance of the electron transfer potential within the electron transport chain?
What is the significance of the electron transfer potential within the electron transport chain?
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Flavins, as electron carriers, have a specific feature. What is it?
Flavins, as electron carriers, have a specific feature. What is it?
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In the context of respiration, what is primarily indicated by the standard reduction potentials (E0')?
In the context of respiration, what is primarily indicated by the standard reduction potentials (E0')?
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What does a higher standard reduction potential (E0') indicate for an electron acceptor?
What does a higher standard reduction potential (E0') indicate for an electron acceptor?
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Which redox couple is recognized as the strongest reductant based on its standard reduction potential?
Which redox couple is recognized as the strongest reductant based on its standard reduction potential?
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Study Notes
Biochemistry and Cell Biology - Bioenergetics
- Course code: BS31004
- Lecturer: Marios Stavridis
- University: University of Dundee
Intended Learning Outcomes
- Students should understand the structure and function of mitochondria.
- Students should appreciate the central principles of chemiosmotic theory.
- Students should have detailed knowledge of the respiratory electron transport chain's structure, function, and molecular mechanism.
- Students should be familiar with the molecular basis of ATP synthesis and its coupling with the respiratory electron transport chain function.
Mitochondrion Structure
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Outer membrane: surrounds the mitochondrion.
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Inner membrane: folded into cristae, increasing surface area.
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Intermembrane space: area between the inner and outer membranes.
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Matrix: inner compartment of the mitochondrion.
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Main functions within the matrix: ATP synthesis, the TCA Cycle, β-oxidation, and the Urea Cycle.
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Mitochondrial ribosomes (55S): present in the matrix
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Mitochondrial genome (16.5 kbp, 22 tRNAs, 2 rRNAs, 13 ORFs): present in the matrix
Biogenesis of Mitochondria
- Fusion: process of mitochondria joining together (mfn1 and 2, OPA1 proteins).
- Fission: process of mitochondria splitting apart (Drp1 protein).
- Mutations in mfn2 and OPA1 can lead to Charcot-Marie-Tooth neuropathy.
Degradation of Mitochondria - Mitophagy
- Degradation can be triggered by starvation events.
- Mitophagy is a process where damaged mitochondria are broken down.
Energy Transduction
- Proton electrochemical gradient: high concentration of protons in the intermembrane space relative to the matrix.
- This creates a difference in voltage and pH between the matrix and the intermembrane space.
- Δψ (membrane potential): voltage difference across the inner mitochondrial membrane, approximately -200 mV.
- ΔpH (pH gradient): the difference in pH between the matrix and IMS, approximately ~ 0.5.
- Free energy (G) in the gradient can be calculated using the formula G = n F Δ.
Respiration
- Electron transfer within proteins - cofactors: Flavins, Fe-S clusters, and haem proteins facilitate electron transfer amongst proteins.
- Flavins can carry two electrons at a time.
- Fe-S clusters can carry one electron at a time.
- Haem proteins can carry one electron at a time.
- Electron carriers: quinones (ubiquinone, menaquinone, demethylmenaquinone) facilitating electron transfer. Quinones can carry two electrons at a time.
- Redox potentials of relevant cofactors and compounds are important for understanding electron flow in the respiratory chain.
- Electron flow powers proton pumps and creates the proton electrochemical gradient. This gradient is crucial for ATP synthesis.
- Key compounds such as glycerol-3-P, fatty acids, succinate, and others can be oxidized and donate electrons in the respiratory process.
Mitochondrion ATP Synthesis
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ATP synthesis occurs through Complex V.
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The proton gradient powers ATP synthase (Complex V).
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Specific inhibitors such as rotenone, malonate, antimycin, cyanide, and oligomycin can inhibit the electron transport chain and affect ATP synthesis.
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P/O ratio: amount of ATP produced per O2 consumed. Generally, ~3-4 protons are required to make each ATP.
Uncoupling
- Uncoupling proteins (UCP) can dissipate the proton electrochemical gradient as heat.
- Dinitrophenol (DNP) is another uncoupler that can also dissipate the proton electrochemical gradient thereby reducing ATP efficiency.
- Brown fat mitochondria: particularly active in uncoupling to regulate heat generation.
- Uncoupling protein 1 (UCP1) plays a central role in brown fat mitochondria for heat production.
Summary
- Energy production in cells follows thermodynamics rules using complex biochemical pathways.
- Electron flow powers proton pumps to generate a chemiosmotic gradient.
- Electron transfer is facilitated by various compounds (quinones, etc.)
- A key concept is the link between the electrochemical proton gradient and ATP synthesis.
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Description
This quiz covers essential concepts in bioenergetics for the Biochemistry course BS31004. Students will delve into the structure and function of mitochondria, the principles of chemiosmotic theory, and the processes involved in ATP synthesis and the respiratory electron transport chain. Test your understanding of these critical cellular mechanisms and their implications in biochemistry.
