30 Questions
How many complexes are involved in electron transport in the electron transport chain?
Four complexes: I, II, III, and IV
Which complex is not involved in the transport of H+ ions?
Complex II (succinate dehydrogenase)
Which complex catalyzes the transfer of electrons from succinate to FAD to ubiquinone without transport of H+?
Complex II (succinate dehydrogenase)
Which enzyme is used in both the TCA and ETC?
Succinate dehydrogenase
What is the total number of H+ ions transported per pair of electrons by Complex III (cytochrome bc1)?
Four H+ ions
Which component of the proton gradient creates a pH gradient?
Concentration gradient of hydrogen ions between matrix and intermembrane space
What metabolic poisons bind catalytic sites in Complex IV (cytochrome c oxidase)?
CO, N3–, and CN–
Which complex catalyzes the transfer of electrons to O2?
Complex IV (cytochrome c oxidase)
What establishes the electric potential across the inner mitochondrial membrane?
Separation of charge across the membrane
Which complex catalyzes the transfer of electrons from NADH to ubiquinone?
Complex I (NADH dehydrogenase)
Which organelle contains enzymes for metabolic reactions and oxidative activities?
Peroxisomes
What is the lipid-soluble agent that uncouples glucose oxidation and ATP formation in mitochondria?
DNP
Which enzyme is responsible for ATP formation in mitochondria?
ATP synthase
What is the rare inherited disease characterized by neurologic, visual, and liver abnormalities due to peroxisome deficiency?
Zellweger syndrome
What visualizes the proton-electrochemical energy in active mitochondria with gradients?
Proton-motive force (p)
What causes excessive heat production in mitochondria by shuttling protons between intermembrane space and matrix?
DNP
What accounts for variations in metabolism rates due to differences in endogenous uncoupling proteins?
Endogenous uncoupling proteins (UCPs)
What explains how a proton electrochemical gradient drives ATP synthesis?
Paul Boyer's binding change mechanism hypothesis
What is the enzyme responsible for ATP formation in mitochondria composed of F1 and F0 portions?
ATP synthase
What are mitochondrial disorders often linked to mutations in and inherited maternally?
mtDNA
What is a special feature of mitochondrial DNA (mtDNA) mentioned in the text?
High mutation rate
Which factor makes mtDNA attractive to scientists?
High copy number in cell
What is speculated to be a major cause of aging based on the text?
Accumulations of mutations in mtDNA
What phenotype is caused by increased mutations in mtDNA according to the text?
Premature-aging phenotype
What is responsible for mtDNA replication?
Mitochondrial DNA polymerase
What do additional findings suggest about mutations in mtDNA?
They may cause premature aging but are not sufficient for the normal aging process
What is shown in the electron micrograph within the mitochondrial matrix?
Crystalline structures
What encodes for the DNA polymerase responsible for mtDNA replication?
Defective nuclear gene
What is the cause of signs of premature aging in mice according to the text?
Mutation in their mtDNA
What is a consequence of abnormal proliferation of mitochondria?
Red-staining 'blotches'
Study Notes
Mitochondrial Function and DNP: A Detailed Overview
- Proton-motive force (p) visualizes the proton-electrochemical energy in active mitochondria with gradients
- Treatment with DNP uncouples glucose oxidation and ATP formation by increasing inner membrane permeability to H+
- DNP, a lipid-soluble agent, inhibits ATP formation and was historically used as a deadly diet pill
- Differences in endogenous uncoupling proteins (UCPs) account for variations in metabolism rates
- DNP inserts into the inner mitochondrial membrane, shuttling protons between intermembrane space and matrix, causing excessive heat production
- ATP synthase is the enzyme responsible for ATP formation in mitochondria
- The enzyme consists of two major portions, F1 and F0, with F0 containing a channel for proton conduction
- The number of subunits in the F0 particle's c ring varies (10-14) and is dependent on the enzyme source
- Paul Boyer's binding change mechanism hypothesis explains how a proton electrochemical gradient drives ATP synthesis
- Peroxisomes are small organelles containing enzymes for metabolic reactions and oxidative activities
- Zellweger syndrome is a rare inherited disease characterized by neurologic, visual, and liver abnormalities due to peroxisome deficiency
- Mitochondrial disorders are often linked to mutations in mtDNA and are inherited maternally
Test your knowledge on mitochondrial function, the role of DNP, ATP formation, uncoupling proteins, and related organelles and disorders.
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