Questions and Answers
What is the primary function of oxidative phosphorylation in cellular respiration?
Which component of the Electron Transport Chain (ETC) is responsible for carrying a single electron from complex III to complex IV?
Which of the following statements accurately describes a role of Coenzyme Q in oxidative phosphorylation?
How many ATP are generated from one glucose molecule during glycolysis?
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What type of reaction primarily occurs at Complex I of the Electron Transport Chain?
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Which of the following is NOT a byproduct of one glucose molecule during oxidative phosphorylation?
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During oxidative phosphorylation, the reduced electron carriers primarily originate from which metabolic processes?
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Which of the following best represents the role of ATP in cellular metabolism?
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What is the final acceptor of electrons in the electron transport chain?
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How many protons are transported across the inner mitochondrial membrane to synthesize one ATP molecule?
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What is the primary function of ATP synthase?
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What role do uncouplers like DNP play in oxidative phosphorylation?
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What is the purpose of the binding-change model in the function of ATP synthase?
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Which of the following statements is true regarding the proton gradient produced during oxidative phosphorylation?
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What effect does oligomycin have on cellular respiration?
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Which complex in the electron transport chain is known to be blocked by cyanide?
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What is one outcome of the electrochemical gradient created by redox reactions in mitochondria?
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What is thermogenin, also known as UCP1, primarily responsible for?
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Study Notes
Oxidative Phosphorylation Overview
- Cellular respiration involves breaking down glucose to produce ATP, the energy currency of cells.
- The process occurs in three major stages:
- Acetyl CoA production (glycolysis)
- Acetyl CoA oxidation (TCA cycle)
- Electron transfer and oxidative phosphorylation.
Glycolysis and Energy Yield
- Glycolysis produces a net yield of 2 ATP and 2 NADH per glucose molecule.
- Pyruvate decarboxylation generates 2 NADH (one for each pyruvate).
- The TCA cycle, which runs twice per glucose, yields:
- 6 NADH
- 2 FADH2
- 2 GTP (converted to ATP).
Role of ATP and Electron Carriers
- ADP is compared to a partially charged battery, while ATP is a fully charged battery.
- The electron transport chain (ETC) acts like a charger, converting ADP into ATP.
- The conclusion of energy production is through oxidative phosphorylation, utilizing reduced electron carriers from previous processes.
Electron Transport Chain Components
- The ETC consists of 5 protein complexes:
- Complex I: NADH dehydrogenase
- Complex II: Succinate dehydrogenase
- Complex III: Ubiquinone:cytochrome c oxidoreductase
- Complex IV: Cytochrome oxidase
- Additionally, two mobile electron carriers are involved:
- Coenzyme Q (ubiquinone) shuttles electrons between complexes.
- Cytochrome c transfers electrons from complex III to complex IV.
Electron Flow Dynamics
- Electron flow within the ETC is driven by increasing standard electrode potentials from negative to positive.
- Electrons lose energy as they move through the chain, which can be harnessed for work, with oxygen serving as the final electron acceptor.
Chemiosmotic Coupling and ATP Synthesis
- Protons (H+) are pumped into the intermembrane space, creating an electrochemical gradient known as chemiosmotic coupling.
- Protons flow through ATP synthase (Complex V) to convert ADP and inorganic phosphate (Pi) into ATP.
- ATP synthase comprises two components:
- FO: Transports H+ across the membrane.
- F1: The catalytic site in the matrix that synthesizes ATP.
ATP Yield and Mechanism
- Approximately 30-32 ATP molecules are generated from the complete oxidation of one glucose molecule.
- The actual yield can vary due to proton leakages across the inner mitochondrial membrane.
Uncoupling Mechanisms in Oxidative Phosphorylation
- Uncoupling disconnects the ETC from ATP synthesis and can be caused by uncouplers that allow protons to move across membranes independently.
- Uncoupling results in reduced ATP production, increased O2 consumption, and heat generation.
- Examples of uncouplers include:
- Cyanide, which blocks Complex IV.
- Venturicidin/oligomycin, which inhibits ATP synthase.
- Dinitrophenol (DNP): an early diet pill that acts as a protonophore, bypassing ATP synthase, potentially leading to lethal effects.
Uncoupling Protein
- Uncoupling protein 1 (UCP1 or thermogenin) facilitates heat generation by dissipating the proton gradient, promoting energy expenditure without ATP production.
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Description
This quiz covers the process of oxidative phosphorylation within cell respiration. It reviews how glucose is broken down to produce ATP, the role of adenosine tri-phosphate as the energy currency, and the stages involved, from glycolysis to the TCA cycle and electron transfer. Test your understanding of these critical biochemical processes!
