Podcast
Questions and Answers
What are the main products generated from one acetyl-CoA entering the TCA cycle?
What are the main products generated from one acetyl-CoA entering the TCA cycle?
- 2 FADH2, 10 H+, and 2 CO2
- 3 CO2, 2 NADH, and ADP
- 6 CO2, 10 NADH, and 4 ATP
- 2 CO2, 3 NADH, FADH2, CoASH, and ATP (correct)
In the complete oxidation of acetate, what role do electron carriers play?
In the complete oxidation of acetate, what role do electron carriers play?
- They convert NAD+ into glucose.
- They directly produce ATP without the need for further reactions.
- They substitute the need for glucose metabolism.
- They help conserve free energy by transporting electrons. (correct)
What effect does glycolysis have on the TCA cycle?
What effect does glycolysis have on the TCA cycle?
- It decreases the overall energy yield of cellular respiration.
- It generates pyruvate which is converted to acetyl-CoA for entry into the TCA cycle. (correct)
- It eliminates the need for the TCA cycle.
- It produces oxygen required for the TCA cycle.
During the complete oxidation of glucose through glycolysis and the TCA cycle, how many CO2 molecules are produced?
During the complete oxidation of glucose through glycolysis and the TCA cycle, how many CO2 molecules are produced?
Why is the oxidation of acetyl-CoA to CO2 significant in metabolism?
Why is the oxidation of acetyl-CoA to CO2 significant in metabolism?
What is the role of pyruvate dehydrogenase (E1) in the reaction?
What is the role of pyruvate dehydrogenase (E1) in the reaction?
Which molecule participates first in the nucleophilic attack in the pyruvate dehydrogenase reaction?
Which molecule participates first in the nucleophilic attack in the pyruvate dehydrogenase reaction?
What by-product is formed upon the departure of CO2 during the reaction?
What by-product is formed upon the departure of CO2 during the reaction?
What happens to TPP after the transfer of the hydroxyethyl group?
What happens to TPP after the transfer of the hydroxyethyl group?
Which compound is formed when the hydroxyethyl group is added to the lipoamide moiety?
Which compound is formed when the hydroxyethyl group is added to the lipoamide moiety?
What is the final product transferred to CoA in this reaction sequence?
What is the final product transferred to CoA in this reaction sequence?
During which step is the hydroxyethyl carbanion generated?
During which step is the hydroxyethyl carbanion generated?
What is the final role of dihydrolipoamide in the reaction sequence?
What is the final role of dihydrolipoamide in the reaction sequence?
What spectral peak is observed when NAD+ is reduced to NADH?
What spectral peak is observed when NAD+ is reduced to NADH?
What is the primary reason the Krebs cycle is referred to as the Tricarboxylic Acid (TCA) cycle?
What is the primary reason the Krebs cycle is referred to as the Tricarboxylic Acid (TCA) cycle?
Which enzyme of the TCA cycle is membrane-bound and what cofactor does it utilize?
Which enzyme of the TCA cycle is membrane-bound and what cofactor does it utilize?
How many enzymes in the TCA cycle function far from equilibrium under physiological conditions?
How many enzymes in the TCA cycle function far from equilibrium under physiological conditions?
What is the primary function of the keto group in the decarboxylation process?
What is the primary function of the keto group in the decarboxylation process?
Which coenzyme is involved in the mechanism of the α-ketoglutarate dehydrogenase?
Which coenzyme is involved in the mechanism of the α-ketoglutarate dehydrogenase?
Which of the following statements about the TCA cycle is incorrect?
Which of the following statements about the TCA cycle is incorrect?
What is produced alongside NADH during the oxidative decarboxylation of α-keto acids?
What is produced alongside NADH during the oxidative decarboxylation of α-keto acids?
Which enzyme is NOT part of the multienzyme complex involved in α-ketoglutarate dehydrogenase?
Which enzyme is NOT part of the multienzyme complex involved in α-ketoglutarate dehydrogenase?
How does Mn2+ interact with the carbonyl group during the dehydrogenase reaction?
How does Mn2+ interact with the carbonyl group during the dehydrogenase reaction?
What effect does the oxidative decarboxylation have on cellular metabolism?
What effect does the oxidative decarboxylation have on cellular metabolism?
What pathway can NADH from the dehydrogenase reaction follow?
What pathway can NADH from the dehydrogenase reaction follow?
What distinguishes the α-ketoglutarate dehydrogenase reaction from others in the citric acid cycle?
What distinguishes the α-ketoglutarate dehydrogenase reaction from others in the citric acid cycle?
What inhibits the activity of the pyruvate dehydrogenase complex (PDC)?
What inhibits the activity of the pyruvate dehydrogenase complex (PDC)?
Which of the following is an anaplerotic pathway for the TCA cycle?
Which of the following is an anaplerotic pathway for the TCA cycle?
Through which compound do valine and isoleucine enter the TCA cycle?
Through which compound do valine and isoleucine enter the TCA cycle?
What is the DGo' value for the hydrolysis of the thioester bond of Acetyl-CoA?
What is the DGo' value for the hydrolysis of the thioester bond of Acetyl-CoA?
Which metabolic process is primarily responsible for generating precursor molecules for the TCA cycle?
Which metabolic process is primarily responsible for generating precursor molecules for the TCA cycle?
Which two compounds are generated as intermediates in the TCA cycle through transamination?
Which two compounds are generated as intermediates in the TCA cycle through transamination?
Which compound is formed from the reversible conversion of glutamate in many tissues?
Which compound is formed from the reversible conversion of glutamate in many tissues?
What platform does odd-chain fatty acid oxidation primarily feed into the TCA cycle?
What platform does odd-chain fatty acid oxidation primarily feed into the TCA cycle?
What is the primary function of FAD in the oxidation of alkanes?
What is the primary function of FAD in the oxidation of alkanes?
Which molecule is oxidized by NAD+ during the metabolic processes described?
Which molecule is oxidized by NAD+ during the metabolic processes described?
What does FADH2 reduce in the electron transport chain?
What does FADH2 reduce in the electron transport chain?
Which enzyme is described as the only membrane-bound TCA cycle enzyme?
Which enzyme is described as the only membrane-bound TCA cycle enzyme?
What is the outcome when succinate is oxidized in the presence of FAD?
What is the outcome when succinate is oxidized in the presence of FAD?
What type of reaction characterizes the process involving succinate and FAD?
What type of reaction characterizes the process involving succinate and FAD?
What role does CoA-SH play in the context of succinate dehydrogenase?
What role does CoA-SH play in the context of succinate dehydrogenase?
What is generated alongside NADH during the oxidation of succinate?
What is generated alongside NADH during the oxidation of succinate?
What does the oxidation of an alkane to an alkene achieve in terms of energy change?
What does the oxidation of an alkane to an alkene achieve in terms of energy change?
What is the fate of electrons during the oxidation of succinate?
What is the fate of electrons during the oxidation of succinate?
Flashcards
Pyruvate Dehydrogenase Reaction
Pyruvate Dehydrogenase Reaction
A multi-step reaction catalyzed by an enzyme complex to convert pyruvate to acetyl-CoA, a crucial step in cellular respiration.
TPP's Role
TPP's Role
Thiamine pyrophosphate (TPP) acts as a coenzyme, facilitating the nucleophilic attack on pyruvate.
Carbon Dioxide Release
Carbon Dioxide Release
Step in the reaction where carbon dioxide is detached from pyruvate.
Hydroxyethyl-TPP Formation
Hydroxyethyl-TPP Formation
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Lipoamide Transfer
Lipoamide Transfer
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Acetyl-CoA Formation
Acetyl-CoA Formation
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Enzyme Complex Role
Enzyme Complex Role
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Coenzyme A (CoA)
Coenzyme A (CoA)
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α-ketoglutarate dehydrogenase
α-ketoglutarate dehydrogenase
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Oxidative decarboxylation
Oxidative decarboxylation
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NAD+-dependent
NAD+-dependent
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Citric Acid Cycle
Citric Acid Cycle
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Succinyl-CoA Synthetase
Succinyl-CoA Synthetase
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Electron Transport Pathway
Electron Transport Pathway
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Oxidative Phosphorylation
Oxidative Phosphorylation
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Multienzyme complex
Multienzyme complex
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FAD oxidation of alkanes
FAD oxidation of alkanes
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NAD+ oxidation of alcohols
NAD+ oxidation of alcohols
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Succinate Dehydrogenase
Succinate Dehydrogenase
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FADH2 reoxidation
FADH2 reoxidation
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Succinate oxidation
Succinate oxidation
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FAD reduction
FAD reduction
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Redox reaction
Redox reaction
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TCA cycle enzyme
TCA cycle enzyme
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Oxidation of Succinate
Oxidation of Succinate
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TCA Cycle: Energy Output
TCA Cycle: Energy Output
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Acetyl-CoA's Role
Acetyl-CoA's Role
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TCA Cycle: Oxidative Process
TCA Cycle: Oxidative Process
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Glucose Complete Oxidation
Glucose Complete Oxidation
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Electron Carriers: TCA's Importance
Electron Carriers: TCA's Importance
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NAD+ Reduction Observation
NAD+ Reduction Observation
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Tricarboxylic Acid Cycle
Tricarboxylic Acid Cycle
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Membrane-Bound TCA Enzyme
Membrane-Bound TCA Enzyme
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TCA Enzymes Far from Equilibrium
TCA Enzymes Far from Equilibrium
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Thiazolium Ring
Thiazolium Ring
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PDC Activity: NADH & Acetyl-CoA
PDC Activity: NADH & Acetyl-CoA
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Anaplerotic Pathways
Anaplerotic Pathways
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Pyruvate Carboxylase
Pyruvate Carboxylase
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Transaminases (TA)
Transaminases (TA)
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TCA Cycle: Biosynthetic Precursors
TCA Cycle: Biosynthetic Precursors
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Acetyl-CoA Thioester Bond Hydrolysis
Acetyl-CoA Thioester Bond Hydrolysis
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Thiazolium Ring in TPP
Thiazolium Ring in TPP
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TPP's Role in PDC
TPP's Role in PDC
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Study Notes
Tricarboxylic Acid (TCA) Cycle
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The TCA cycle, also known as the Krebs cycle or citric acid cycle, is a crucial metabolic pathway.
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It's a central part of cellular respiration, oxidizing acetyl-CoA to carbon dioxide.
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The cycle involves eight steps, each catalyzed by a specific enzyme.
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Acetyl-CoA enters the cycle by combining with oxaloacetate, forming citrate.
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The seven subsequent steps decompose citrate back to oxaloacetate, creating a cyclical process.
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NADH and FADH2 are produced during the cycle, crucial for electron transport.
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The cycle relays electrons extracted from food to the electron transport chain.
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The cycle provides a way to cleave a two-carbon compound such as acetate to carbon dioxide.
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A common type of C-C cleavage is a-cleavage.
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Neither cleavage strategies are suitable for acetate. Instead, living things use the clever chemistry of condensing acetate to oxaloacetate and undergoing a B-cleavage.
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The TCA cycle combines this B-cleavage reaction with oxidation to form CO2, regenerate oxaloacetate, and capture the liberated metabolic energy in NADH and ATP.
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Important intermediates for biosynthetic processes are produced by the Citric Acid Cycle including carbohydrates, amino acids, lipids and other molecules such as porphyrins.
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Pyruvate carboxylase and glutamate are two major anaplerotic pathways.
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The pyruvate dehydrogenase complex links glycolysis to the TCA cycle.
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The Pyruvate Dehydrogenase Multienzyme Complex (PDC) is a cluster of three enzymes catalyzing the conversion of pyruvate to acetyl-CoA.
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PDC requires five cofactors including thiamine pyrophosphate (TPP), lipoic acid, coenzyme A, flavin adenine dinucleotide (FAD), and NAD+.
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The reaction occurs in the mitochondrial matrix.
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The dihydrolipoyl transacetylase is the core of the complex.
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The 24 subunits of the Eâ‚‚ form a particle having cubic symmetry.
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The 24 pyruvate dehydrogenase subunits form dimers and associate with the Eâ‚‚ core at the centers of the 12 edges.
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The 12 dihydrolipoyl dehydrogenase form dimers and attach to the E2 cube at the centers of the 6 faces.
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The coenzymes and prosthetic groups for the PDC include thiamine pyrophosphate (TPP), lipoic acid, coenzyme A (CoA), flavin adenine dinucleotide (FAD), and nicotinamide adenine dinucleotide (NAD+).
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In the TCA cycle, carbons come from acetyl-CoA and are oxidized to CO2, the cycle regenerates oxaloacetate, and captures energy in NADH and ATP.
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Key enzymes and their roles in the TCA cycle are detailed (including their enzyme-bound cofactors & the reactions they catalyze).
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The regulation of the TCA cycle includes product inhibition (e.g., citrate inhibits citrate synthase) and control by ADP, NADH and Ca2+.
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Description
Explore the Tricarboxylic Acid (TCA) Cycle, a vital metabolic pathway known for its role in cellular respiration. This quiz covers the cycle's eight steps, enzyme interactions, and the production of NADH and FADH2. Understand how acetyl-CoA transforms into carbon dioxide through this intricate process.
