Podcast
Questions and Answers
What is the result of thiamine (vitamin B1) deficiency?
What is the result of thiamine (vitamin B1) deficiency?
- Increased activity of pyruvate dehydrogenase
- Inhibition of enzymes requiring TPP as a coenzyme (correct)
- Enhanced glucose oxidation
- Decrease in blood pyruvate levels
What is a common symptom of the disease caused by TPP deficiency?
What is a common symptom of the disease caused by TPP deficiency?
- Digestive problems
- Respiratory issues
- Neurological and cardiovascular disorder (correct)
- Skin rashes
What clever chemistry allows living organisms to oxidize acetate in the TCA cycle?
What clever chemistry allows living organisms to oxidize acetate in the TCA cycle?
- Condensation with oxalacetate followed by b-cleavage (correct)
- Formation of acetyl-CoA without condensing reactions
- Direct oxidation of acetate without any cleavage
- Condensation with pyruvate followed by a-cleavage
How can thiamine deficiency be detected in the blood?
How can thiamine deficiency be detected in the blood?
Which food could help treat thiamine deficiency?
Which food could help treat thiamine deficiency?
What is the role of aconitase in the citric acid cycle?
What is the role of aconitase in the citric acid cycle?
Why cannot tertiary alcohols be oxidized easily in the citric acid cycle?
Why cannot tertiary alcohols be oxidized easily in the citric acid cycle?
What type of alcohol is isocitrate classified as?
What type of alcohol is isocitrate classified as?
What is the intermediate formed during the conversion of citrate to isocitrate?
What is the intermediate formed during the conversion of citrate to isocitrate?
How does citrate interact with citrate synthase in the citric acid cycle?
How does citrate interact with citrate synthase in the citric acid cycle?
What characterizes ATP despite being labeled as a high-energy compound?
What characterizes ATP despite being labeled as a high-energy compound?
Which of the following best describes the nature of ATP breakdown?
Which of the following best describes the nature of ATP breakdown?
What does the hexokinase reaction specifically involve?
What does the hexokinase reaction specifically involve?
What happens to carbon atoms during oxidation in organic compounds?
What happens to carbon atoms during oxidation in organic compounds?
What illustrates the term 'high phosphoryl group transfer potential' in ATP?
What illustrates the term 'high phosphoryl group transfer potential' in ATP?
How do carbon atoms become oxidized during the respiratory chain process?
How do carbon atoms become oxidized during the respiratory chain process?
What effect does the nucleophilic attack in hexokinase have?
What effect does the nucleophilic attack in hexokinase have?
Which of the following statements is incorrect about high-energy compounds like ATP?
Which of the following statements is incorrect about high-energy compounds like ATP?
What inhibits the activity of the pyruvate dehydrogenase complex (PDC)?
What inhibits the activity of the pyruvate dehydrogenase complex (PDC)?
Which enzyme is responsible for the formation of oxaloacetate in the TCA cycle?
Which enzyme is responsible for the formation of oxaloacetate in the TCA cycle?
Which of the following pathways contributes to replenishing TCA cycle intermediates?
Which of the following pathways contributes to replenishing TCA cycle intermediates?
Which amino acids are NOT typically associated with the TCA cycle through anaplerotic reactions?
Which amino acids are NOT typically associated with the TCA cycle through anaplerotic reactions?
What is the primary role of the TCA cycle in relation to other metabolic pathways?
What is the primary role of the TCA cycle in relation to other metabolic pathways?
Which compound enters the TCA cycle at the level of succinyl-CoA?
Which compound enters the TCA cycle at the level of succinyl-CoA?
What is the $ riangle G^o$ value for the hydrolysis of the thioester bond of Acetyl-CoA?
What is the $ riangle G^o$ value for the hydrolysis of the thioester bond of Acetyl-CoA?
Which functional group is found in the thiazolium ring of thiamine (TPP)?
Which functional group is found in the thiazolium ring of thiamine (TPP)?
What is succinyl-CoA classified as in the TCA cycle?
What is succinyl-CoA classified as in the TCA cycle?
Which phosphorylation occurs with succinyl-CoA in mammals during the TCA cycle?
Which phosphorylation occurs with succinyl-CoA in mammals during the TCA cycle?
Which molecule is coupled with the formation of GTP in mammals when utilizing succinyl-CoA?
Which molecule is coupled with the formation of GTP in mammals when utilizing succinyl-CoA?
What is the role of the enzyme succinyl-CoA synthetase in the TCA cycle?
What is the role of the enzyme succinyl-CoA synthetase in the TCA cycle?
Which of the following correctly describes the first step in the reaction catalyzed by succinyl-CoA synthetase?
Which of the following correctly describes the first step in the reaction catalyzed by succinyl-CoA synthetase?
In which type of organisms does succinyl-CoA lead to ADP being converted to ATP?
In which type of organisms does succinyl-CoA lead to ADP being converted to ATP?
What is produced when GTP exchanges its terminal phosphoryl group with ADP?
What is produced when GTP exchanges its terminal phosphoryl group with ADP?
Which cofactor is covalently bound to succinate dehydrogenase?
Which cofactor is covalently bound to succinate dehydrogenase?
Which of the following steps takes place after the formation of phosphoryl-His in the reaction catalyzed by succinyl-CoA synthetase?
Which of the following steps takes place after the formation of phosphoryl-His in the reaction catalyzed by succinyl-CoA synthetase?
What is the final product of the reaction involving succinyl-CoA in mammals?
What is the final product of the reaction involving succinyl-CoA in mammals?
What is produced during the conversion of succinyl CoA in the TCA cycle?
What is produced during the conversion of succinyl CoA in the TCA cycle?
Which molecule is directly generated from isocitrate in the TCA cycle?
Which molecule is directly generated from isocitrate in the TCA cycle?
Which of the following components is oxidized during the conversion of succinate to fumarate?
Which of the following components is oxidized during the conversion of succinate to fumarate?
What molecule enters the TCA cycle combining with oxaloacetate?
What molecule enters the TCA cycle combining with oxaloacetate?
What is the role of NAD+ in the TCA cycle?
What is the role of NAD+ in the TCA cycle?
Which compound is produced from the hydration of fumarate?
Which compound is produced from the hydration of fumarate?
What happens to carbon atoms during the TCA cycle?
What happens to carbon atoms during the TCA cycle?
Which process is primarily associated with GTP production in the TCA cycle?
Which process is primarily associated with GTP production in the TCA cycle?
What is the immediate precursor of ATP or GTP in the TCA cycle?
What is the immediate precursor of ATP or GTP in the TCA cycle?
Which coenzyme participates in oxidation during the conversion of succinate?
Which coenzyme participates in oxidation during the conversion of succinate?
What is the role of magnesium ions in the reaction involving ATP investment?
What is the role of magnesium ions in the reaction involving ATP investment?
Which aspect of ATP is crucial for its function as an energy molecule?
Which aspect of ATP is crucial for its function as an energy molecule?
Why is the nucleophilic attack of glucose on ATP considered irreversible?
Why is the nucleophilic attack of glucose on ATP considered irreversible?
What is the first step in the reaction involving glucose and ATP?
What is the first step in the reaction involving glucose and ATP?
What aspect of ATP's structure increases its electrophilicity during nucleophilic attack?
What aspect of ATP's structure increases its electrophilicity during nucleophilic attack?
What type of reaction occurs during the conversion of glucose 6-phosphate to fructose 6-phosphate?
What type of reaction occurs during the conversion of glucose 6-phosphate to fructose 6-phosphate?
What must occur to glucose 6-phosphate before isomerization can take place?
What must occur to glucose 6-phosphate before isomerization can take place?
What characterizes the new carbonyl position after the isomerization of glucose 6-phosphate?
What characterizes the new carbonyl position after the isomerization of glucose 6-phosphate?
What facilitates the subsequent C-C bond cleavage in glycolysis after isomerization?
What facilitates the subsequent C-C bond cleavage in glycolysis after isomerization?
What distinguishes an aldose from a ketose in the context of carbohydrates?
What distinguishes an aldose from a ketose in the context of carbohydrates?
Which enzyme catalyzes the isomerization of glucose 6-phosphate to fructose 6-phosphate?
Which enzyme catalyzes the isomerization of glucose 6-phosphate to fructose 6-phosphate?
What type of carbon structure is formed from fructose 6-phosphate after the isomerization process?
What type of carbon structure is formed from fructose 6-phosphate after the isomerization process?
Which functional group is highlighted as becoming a new feature at C-1 after the isomerization of glucose 6-phosphate?
Which functional group is highlighted as becoming a new feature at C-1 after the isomerization of glucose 6-phosphate?
What role does hexokinase play in glucose metabolism?
What role does hexokinase play in glucose metabolism?
Which of the following statements is true regarding hexokinases?
Which of the following statements is true regarding hexokinases?
What is the product of the enzymatic reaction catalyzed by aldolase?
What is the product of the enzymatic reaction catalyzed by aldolase?
Which enzyme is responsible for the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate?
Which enzyme is responsible for the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate?
What distinguishes different hexokinases from each other?
What distinguishes different hexokinases from each other?
What intermediate is formed during the phosphorylation of glucose?
What intermediate is formed during the phosphorylation of glucose?
What is the main function of phosphoglucoisomerase in glycolysis?
What is the main function of phosphoglucoisomerase in glycolysis?
Which of the following best describes the glycolytic pathway's initial phase?
Which of the following best describes the glycolytic pathway's initial phase?
What is the net yield of ATP per mole of glucose during glycolysis?
What is the net yield of ATP per mole of glucose during glycolysis?
How many moles of NADH are produced per mole of glucose during glycolysis?
How many moles of NADH are produced per mole of glucose during glycolysis?
What indicates that a reaction is thermodynamically favored during glycolysis?
What indicates that a reaction is thermodynamically favored during glycolysis?
During the ATP-generating phase of glycolysis, how many moles of triose phosphate are formed?
During the ATP-generating phase of glycolysis, how many moles of triose phosphate are formed?
What is the change in free energy represented by ΔG in the context of glycolysis?
What is the change in free energy represented by ΔG in the context of glycolysis?
Which substances are produced alongside 2 moles of pyruvate from the glycolysis of one mole of glucose?
Which substances are produced alongside 2 moles of pyruvate from the glycolysis of one mole of glucose?
What characterizes the three large negative standard free-energy changes in glycolysis?
What characterizes the three large negative standard free-energy changes in glycolysis?
Which of the following statements about glycolysis is incorrect?
Which of the following statements about glycolysis is incorrect?
What two phosphorylated three-carbon compounds are generated from the aldol cleavage of fructose 1,6-bisphosphate?
What two phosphorylated three-carbon compounds are generated from the aldol cleavage of fructose 1,6-bisphosphate?
Which enzyme catalyzes the cleavage of fructose 1,6-bisphosphate into triose phosphates?
Which enzyme catalyzes the cleavage of fructose 1,6-bisphosphate into triose phosphates?
What type of reaction mechanism does aldolase utilize in the forward direction?
What type of reaction mechanism does aldolase utilize in the forward direction?
What role does the lysine ε-amino group play in the aldolase reaction?
What role does the lysine ε-amino group play in the aldolase reaction?
Which of the following correctly describes the activity of aldolase in the metabolic pathway?
Which of the following correctly describes the activity of aldolase in the metabolic pathway?
During which phase of glycolysis does aldol cleavage occur?
During which phase of glycolysis does aldol cleavage occur?
Which sugar is isomerized to form Glyceraldehyde 3-phosphate?
Which sugar is isomerized to form Glyceraldehyde 3-phosphate?
What is the main function of aldolase in glycolysis?
What is the main function of aldolase in glycolysis?
What is the primary product of glycolysis after the oxidation of glucose 6-phosphate?
What is the primary product of glycolysis after the oxidation of glucose 6-phosphate?
Which shuttle is involved in transferring reducing equivalents from cytosolic NADH to the electron-transport chain?
Which shuttle is involved in transferring reducing equivalents from cytosolic NADH to the electron-transport chain?
What is the net gain of ATP from one molecule of glucose during glycolysis?
What is the net gain of ATP from one molecule of glucose during glycolysis?
In which cellular location does glycolysis occur?
In which cellular location does glycolysis occur?
What is produced as a result of pyruvate oxidation by pyruvate dehydrogenase?
What is produced as a result of pyruvate oxidation by pyruvate dehydrogenase?
Approximately how many molecules of ATP can be generated from the complete aerobic oxidation of one molecule of glucose?
Approximately how many molecules of ATP can be generated from the complete aerobic oxidation of one molecule of glucose?
What is the first step in glycolysis that involves the phosphorylation of glucose?
What is the first step in glycolysis that involves the phosphorylation of glucose?
How is the reducing equivalent from NADH generated during glycolysis transport across the inner mitochondrial membrane?
How is the reducing equivalent from NADH generated during glycolysis transport across the inner mitochondrial membrane?
What type of polysaccharide is cellulose?
What type of polysaccharide is cellulose?
Which form of starch is more branched and preferred for storage in plants?
Which form of starch is more branched and preferred for storage in plants?
What structural linkages characterize glycogen?
What structural linkages characterize glycogen?
Why is cellulose indigestible for most animals?
Why is cellulose indigestible for most animals?
What is the primary function of starch in plants?
What is the primary function of starch in plants?
Which form of glucose is primarily found in cellulose?
Which form of glucose is primarily found in cellulose?
What distinguishes amylose from amylopectin?
What distinguishes amylose from amylopectin?
What type of molecules does glycogen primarily serve as in animals?
What type of molecules does glycogen primarily serve as in animals?
What does the Km of an enzyme indicate?
What does the Km of an enzyme indicate?
Which type of allosteric interaction occurs when effectors are different from substrate molecules?
Which type of allosteric interaction occurs when effectors are different from substrate molecules?
What shape does the plot of an allosteric interaction typically exhibit?
What shape does the plot of an allosteric interaction typically exhibit?
What is the main function of the urea cycle?
What is the main function of the urea cycle?
When is Vmax of an enzyme typically achieved?
When is Vmax of an enzyme typically achieved?
Which regulatory mechanism allows for changes in enzyme activity through specific chemical modifications?
Which regulatory mechanism allows for changes in enzyme activity through specific chemical modifications?
What does a rectangular hyperbola graph represent in enzyme kinetics?
What does a rectangular hyperbola graph represent in enzyme kinetics?
Which of the following best describes the role of isoenzymes?
Which of the following best describes the role of isoenzymes?
What happens to the Φ and Ψ angles as the carbonyl or amide nitrogens rotate clockwise?
What happens to the Φ and Ψ angles as the carbonyl or amide nitrogens rotate clockwise?
What factors can influence the rotational hindrance of bonds in the backbone?
What factors can influence the rotational hindrance of bonds in the backbone?
What do aromatic amino acids potentially generate when arranged in a specific way?
What do aromatic amino acids potentially generate when arranged in a specific way?
In what state can R groups be depending on their environment?
In what state can R groups be depending on their environment?
What angle is observed when the Φ and Ψ angles are at their maximum in the given conformation?
What angle is observed when the Φ and Ψ angles are at their maximum in the given conformation?
What defines the primary roles of metabolism in biological systems?
What defines the primary roles of metabolism in biological systems?
How do catabolic pathways differ from anabolic pathways?
How do catabolic pathways differ from anabolic pathways?
What role do the sizes and charges of R groups play in conjunction with single bonds in the backbone?
What role do the sizes and charges of R groups play in conjunction with single bonds in the backbone?
Which organ primarily provides quick fuel needs for the body?
Which organ primarily provides quick fuel needs for the body?
Which statement correctly describes the function of aromatic amino acids?
Which statement correctly describes the function of aromatic amino acids?
What role do hormones play in metabolism?
What role do hormones play in metabolism?
What effect do the properties of R groups have on peptide/protein stability?
What effect do the properties of R groups have on peptide/protein stability?
In which manner do insulin and glucagon interact with metabolic pathways?
In which manner do insulin and glucagon interact with metabolic pathways?
What is the effect of hormonal signals on metabolic needs across various organs?
What is the effect of hormonal signals on metabolic needs across various organs?
Which of these hormones is NOT typically involved in regulating metabolism?
Which of these hormones is NOT typically involved in regulating metabolism?
What are the main signals used in the integration of metabolism among organs?
What are the main signals used in the integration of metabolism among organs?
What is one advantage of multienzyme complexes in metabolic pathways?
What is one advantage of multienzyme complexes in metabolic pathways?
How are enzymes for glycolysis and the citric acid cycle segregated in the cell?
How are enzymes for glycolysis and the citric acid cycle segregated in the cell?
What is a feature of membrane-bound enzyme systems?
What is a feature of membrane-bound enzyme systems?
Which compounds are classified as being in a more reduced state relative to others?
Which compounds are classified as being in a more reduced state relative to others?
What primarily drives biosynthetic reactions in living systems?
What primarily drives biosynthetic reactions in living systems?
Why is the compartmentalization of metabolic pathways beneficial?
Why is the compartmentalization of metabolic pathways beneficial?
Which statement best describes soluble multienzyme systems?
Which statement best describes soluble multienzyme systems?
Where are most glycolytic enzymes located in the cell?
Where are most glycolytic enzymes located in the cell?
Which of the following substances are classified as common nucleophiles in biochemical reactions?
Which of the following substances are classified as common nucleophiles in biochemical reactions?
What is the primary consequence of atoms sharing or transferring valence electrons?
What is the primary consequence of atoms sharing or transferring valence electrons?
What is a key advantage of compartmentalizing metabolic pathways within specific organelles?
What is a key advantage of compartmentalizing metabolic pathways within specific organelles?
Which type of chemical bond is characterized by one atom stripping electrons from another?
Which type of chemical bond is characterized by one atom stripping electrons from another?
Which statement accurately describes nucleophiles?
Which statement accurately describes nucleophiles?
What is the role of chemical bonds in the formation of molecules?
What is the role of chemical bonds in the formation of molecules?
Which of the following correctly describes a condition following the transfer of an electron between bonding partners?
Which of the following correctly describes a condition following the transfer of an electron between bonding partners?
What is one consequence of selective permeability of membranes in metabolic pathways?
What is one consequence of selective permeability of membranes in metabolic pathways?
Flashcards
High-energy compound
High-energy compound
A compound that has a high phosphoryl group transfer potential, but is kinetically stable and not unusually reactive.
ATP hydrolysis
ATP hydrolysis
The breakdown of ATP, which is usually coupled with other reactions to make them favorable.
Energy coupling
Energy coupling
ATP hydrolysis providing energy to drive an unfavorable reaction.
Phosphoryl group transfer potential
Phosphoryl group transfer potential
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Hexokinase reaction
Hexokinase reaction
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Nucleophilic attack
Nucleophilic attack
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Oxidative fates of Pyruvate
Oxidative fates of Pyruvate
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Loss of hydride ion
Loss of hydride ion
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Pyruvate Dehydrogenase Complex Inhibition
Pyruvate Dehydrogenase Complex Inhibition
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Beriberi Cause
Beriberi Cause
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TPP Deficiency Symptom
TPP Deficiency Symptom
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TCA Cycle Purpose
TCA Cycle Purpose
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TCA Cycle's Process Detail
TCA Cycle's Process Detail
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Citrate isomerization
Citrate isomerization
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Aconitase
Aconitase
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Tertiary alcohol
Tertiary alcohol
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Isocitrate
Isocitrate
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Citric Acid Cycle
Citric Acid Cycle
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Succinyl-CoA
Succinyl-CoA
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Substrate-level phosphorylation
Substrate-level phosphorylation
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Succinyl-CoA synthetase
Succinyl-CoA synthetase
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High-energy intermediate
High-energy intermediate
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Mixed anhydride
Mixed anhydride
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Phosphoryl–His
Phosphoryl–His
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Nucleoside diphosphate kinase
Nucleoside diphosphate kinase
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Succinate dehydrogenase
Succinate dehydrogenase
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FAD (Flavin Adenine Dinucleotide)
FAD (Flavin Adenine Dinucleotide)
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How is Succinyl-CoA used to drive the phosphorylation of GDP or ADP?
How is Succinyl-CoA used to drive the phosphorylation of GDP or ADP?
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What is the TCA cycle?
What is the TCA cycle?
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What is the starting molecule of the TCA cycle?
What is the starting molecule of the TCA cycle?
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What is the role of oxalacetate?
What is the role of oxalacetate?
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What are the products of the TCA cycle?
What are the products of the TCA cycle?
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How many ATP are produced per glucose molecule in the TCA cycle?
How many ATP are produced per glucose molecule in the TCA cycle?
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What is the significance of NADH and FADH2?
What is the significance of NADH and FADH2?
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Where does the TCA cycle take place?
Where does the TCA cycle take place?
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What is oxidative phosphorylation?
What is oxidative phosphorylation?
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How is the TCA cycle regulated?
How is the TCA cycle regulated?
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PDC Inhibition
PDC Inhibition
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Anaplerotic Pathways
Anaplerotic Pathways
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Pyruvate Carboxylase
Pyruvate Carboxylase
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TCA Cycle Provides Intermediates
TCA Cycle Provides Intermediates
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Acetyl-CoA Thioester Bond Hydrolysis
Acetyl-CoA Thioester Bond Hydrolysis
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TPP in Thiazolium Ring
TPP in Thiazolium Ring
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TCA Cycle - Energy Production
TCA Cycle - Energy Production
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TCA Cycle's Clever Approach
TCA Cycle's Clever Approach
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Glycolysis
Glycolysis
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TCA Cycle
TCA Cycle
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Pyruvate Dehydrogenase
Pyruvate Dehydrogenase
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NADH and FADH2
NADH and FADH2
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Electron transport chain
Electron transport chain
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Anaplerotic reactions
Anaplerotic reactions
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Oxidation
Oxidation
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Why is Mg2+ needed in the first ATP investment?
Why is Mg2+ needed in the first ATP investment?
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What's the role of the γ-phosphorus atom in the first ATP investment?
What's the role of the γ-phosphorus atom in the first ATP investment?
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What does the first ATP investment in glycolysis achieve?
What does the first ATP investment in glycolysis achieve?
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Why is the first ATP investment considered 'exergonic'?
Why is the first ATP investment considered 'exergonic'?
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How does ATP become more reactive in the first ATP investment?
How does ATP become more reactive in the first ATP investment?
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Hexokinase Family
Hexokinase Family
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Energy Investment Phase
Energy Investment Phase
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Glucose 6-Phosphate
Glucose 6-Phosphate
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Fructose 1,6-Bisphosphate
Fructose 1,6-Bisphosphate
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Isomerase
Isomerase
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Aldolase
Aldolase
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Glyceraldehyde 3-Phosphate (G3P)
Glyceraldehyde 3-Phosphate (G3P)
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Dihydroxyacetone Phosphate (DHAP)
Dihydroxyacetone Phosphate (DHAP)
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Glucose 6-Phosphate Isomerization
Glucose 6-Phosphate Isomerization
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Why Isomerize Glucose 6-Phosphate?
Why Isomerize Glucose 6-Phosphate?
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Cyclic Forms of Sugars
Cyclic Forms of Sugars
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Aldose to Ketose
Aldose to Ketose
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Phosphoglucose Isomerase
Phosphoglucose Isomerase
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Primary Alcohol at Carbon 1
Primary Alcohol at Carbon 1
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Activation of Carbon 3
Activation of Carbon 3
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Glycolysis's First Step
Glycolysis's First Step
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Aldolase Cleavage
Aldolase Cleavage
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Aldol Cleavage Mechanism
Aldol Cleavage Mechanism
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Aldolase's Dual Roles
Aldolase's Dual Roles
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Keto Carbon
Keto Carbon
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Lysine ε-Amino Group
Lysine ε-Amino Group
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Glycolysis: Energy Yield
Glycolysis: Energy Yield
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Irreversible Steps in Glycolysis
Irreversible Steps in Glycolysis
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Thermodynamically Favored Reactions
Thermodynamically Favored Reactions
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NADH: Electron Carrier
NADH: Electron Carrier
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Pyruvate: End Product of Glycolysis
Pyruvate: End Product of Glycolysis
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Importance of Substrate-Level Phosphorylation
Importance of Substrate-Level Phosphorylation
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Regulation of Glycolysis
Regulation of Glycolysis
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Cellulose Structure
Cellulose Structure
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Starch
Starch
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Amylose vs Amylopectin
Amylose vs Amylopectin
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Glycogen
Glycogen
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Why is Cellulose Indigestible?
Why is Cellulose Indigestible?
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What is the Difference Between Starch and Glycogen?
What is the Difference Between Starch and Glycogen?
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Polysaccharide Function
Polysaccharide Function
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α vs β Glucose
α vs β Glucose
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Rotationally Hindered Bonds
Rotationally Hindered Bonds
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Φ and Ψ Angles
Φ and Ψ Angles
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Aromatic Amino Acids Stacking
Aromatic Amino Acids Stacking
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Protonation/Deprotonation of Amino Acids
Protonation/Deprotonation of Amino Acids
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pH Dependence of Amino Acid Charge
pH Dependence of Amino Acid Charge
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Conformational Flexibility of the Backbone
Conformational Flexibility of the Backbone
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Force Generation from Amino Acid Interactions
Force Generation from Amino Acid Interactions
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Architecture and Stability of Peptides/Proteins
Architecture and Stability of Peptides/Proteins
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Michaelis-Menten Equation
Michaelis-Menten Equation
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Km (Michaelis Constant)
Km (Michaelis Constant)
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Vmax (Maximum Velocity)
Vmax (Maximum Velocity)
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Allosteric Regulation
Allosteric Regulation
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Heterotropic Allostery
Heterotropic Allostery
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Homotropic Allostery
Homotropic Allostery
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Sigmoid Curve
Sigmoid Curve
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Feedback Control
Feedback Control
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Catabolic Pathway
Catabolic Pathway
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Anabolic Pathway
Anabolic Pathway
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Metabolic Map
Metabolic Map
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Liver's Role in Metabolism
Liver's Role in Metabolism
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Adipose Tissue's Role in Metabolism
Adipose Tissue's Role in Metabolism
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Insulin and Glucagon
Insulin and Glucagon
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Energy-Rich Compounds
Energy-Rich Compounds
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Catabolism and Anabolism
Catabolism and Anabolism
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Nucleophiles
Nucleophiles
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Common Nucleophiles in Biochemistry
Common Nucleophiles in Biochemistry
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Chemical Bonds
Chemical Bonds
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Covalent Bonds
Covalent Bonds
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Ionic Bonds
Ionic Bonds
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Nucleophilic Substitution
Nucleophilic Substitution
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Compartmentalization in Metabolism
Compartmentalization in Metabolism
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Metabolic Functions of Eukaryotic Organelles
Metabolic Functions of Eukaryotic Organelles
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Multienzyme Systems
Multienzyme Systems
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TCA Cycle Location
TCA Cycle Location
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Oxidation of Organic Substrates
Oxidation of Organic Substrates
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State of Reduction
State of Reduction
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Glycolysis End Product
Glycolysis End Product
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Study Notes
Tricarboxylic Acid (TCA) Cycle
- The TCA cycle, also known as the Krebs cycle or citric acid cycle, is a crucial part of cellular respiration.
- It's a cyclical series of biochemical reactions that oxidizes the acetyl group from acetyl-CoA to carbon dioxide (CO2).
- The cycle regenerates oxaloacetate, starting the cycle again.
- It generates high-energy electron carriers (NADH and FADH2) and a small amount of ATP (GTP).
- The TCA cycle is an amphibolic pathway, meaning it plays a role in both catabolic (breakdown) and anabolic (synthesis) processes.
- Key enzymes in the cycle are: citrate synthase, aconitase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, and malate dehydrogenase.
- The cycle takes place in the mitochondrial matrix.
- Pyruvate dehydrogenase complex connects glycolysis and the TCA cycle by converting pyruvate to acetyl-CoA.
- Anaplerotic reactions replenish TCA cycle intermediates like oxaloacetate.
Energy Transformations in Fuel Metabolism
- Phase 1 of respiration involves the oxidation of fuels (glucose, fatty acids, amino acids), transferring electrons.
- Coenzymes NAD+ and FAD accept the transferred electrons, forming NADH and FAD(2H) respectively.
- Phase 2 of respiration generates ATP through oxidative phosphorylation using the energy from the high-energy electron carriers (NADH and FAD(2H)).
Overview of Glycolysis and Important Reactions
- Glycolysis is an anaerobic process that converts glucose into pyruvate.
- Important reactions like hexokinase, phosphofructokinase, and pyruvate kinase are involved in these conversions.
- ATP is required in glycolysis, but a net gain of 2 ATP is yielded.
- These reactions take place in the cytosol.
Oxidative Fates of Pyruvate and Nicotinamide Adenine Dinucleotide
- Aerobic glycolysis utilizes pyruvate to make Acetyl CoA to enter the TCA cycle.
- Anaerobic glycolysis converts pyruvate into lactate.
- Oxidation of organic compounds either involves loss of hydride ions (H−) or combining with oxygen.
- Enzymes called dehydrogenases are responsible for these oxidation reactions.
Anaerobic Conversion of Pyruvate to Ethanol
- Yeast cells convert pyruvate to ethanol and CO2 in the absence of oxygen.
- Two reactions are necessary. One being decarboxylation to pyruvate then to acetaldehyde, and the other being alcohol dehydrogenase reducing acetaldehyde to ethanol.
- This process regenerates NAD+ from NADH allowing glycolysis to continue.
The Citric Acid Cycle and What We Will Learn Today
- The citric acid cycle (TCA cycle) is a cyclical process.
- The cycle interconnects glycolysis and pyruvate dehydrogenase complex.
- The cycle's reactions and the enzymes involved in the reactions.
- Regulation of TCA cycle activity.
- Anaplerotic reaction that replenishes TCA cycle intermediates.
The Loci of Substrate-Level Phosphorylation
- Substrate-level phosphorylation occurs in the cytosol during glycolysis and in the mitochondrion during the TCA cycle.
- Electrons are transferred via NADH and FAD(2H) in these processes.
Conversion of Pyruvate to Acetyl-CoA by Oxidative Decarboxylation
- The conversion is carried out by the pyruvate dehydrogenase complex (PDC), a multi-enzyme complex.
- The PDC requires five cofactors: TPP, lipoic acid, CoA, FAD, and NAD+.
- The reaction takes place in the mitochondrial matrix.
Acetyl-Coenzyme A (Acetyl-CoA)
- Acetyl-CoA carries acetyl groups for metabolic processes.
- It's a high-energy molecule that releases free energy for cellular reactions.
- The common product of breakdown of carbohydrate, fatty acids, and amino acids.
Comparison of Free Energies of Hydrolysis of Thioesters and Oxygen Esters
- Thioesters are more favorable for hydrolysis than oxygen esters.
- Lack of resonance stabilization in thioesters is why their hydrolysis is more favorable compared to oxygen esters.
Conversion of Pyruvate to Acetyl-CoA by Oxidative Decarboxylation (Alternative)
- Pyruvate Dehydrogenase Multienzyme Complex (PDC) catalyzes the conversion.
- The PDC has three enzymes: E1 (pyruvate dehydrogenase), E2 (dihydrolipoyl transacetylase), and E3 (dihydrolipoyl dehydrogenase).
- Five cofactors are needed: TPP, lipoic acid, CoASH, FAD, NAD+.
- Occurs in the mitochondrial matrix.
Structural Organization of the E. coli PDC
- PDC is a multi-enzyme complex with a structure (E1, E2, E3) core. The structure is important to understand the mechanism in which they work together.
The Coenzymes and Prosthetic Groups of PDC
- Different coenzymes within the PDC facilitate different reaction steps, with TPP, lipoic acid, CoA (respectively E1, E2), and FAD & NAD+ (in E3) involved in specific parts and steps.
- The roles of TPP and lipoic acid.
- The role of CoA and FAD
- The role of NAD+ within the complex.
Interconversion of Lipoamide and Dihydrolipoamide
- Lipoamide is a cofactor involved in the conversion of lipoic acid in the PDC complex, and crucial to the process.
Thiamine Pyrophosphate (TPP)
- TPP is a cofactor of pyruvate dehydrogenase complex.
- It's involved in decarboxylation of pyruvate and transfer of a two-carbon unit.
TPP in the Pyruvate Dehydrogenase Reaction
- TPP plays a key role in the pyruvate dehydrogenase reaction, accepting the activated two-carbon unit of pyruvate, then transferring to an intermediate then to the next cofactor, CoA, which then becomes acetyl CoA.
- The pyruvate dehydrogenase reaction, and each step is essential in order for the entire process to happen.
Malfunction of Pyruvate Dehydrogenase Complex: TPP Deficiency
- TPP deficiency inhibits pyruvate dehydrogenase complex activity.
- Symptoms of TPP deficiency include neurological and cardiovascular disorders.
- Deficiency can be diagnosed by testing the levels of pyruvate in the blood.
TCA Cycle Provides a Way of Cleaving a Two-Carbon Compound
- The TCA cycle provides a means to oxidize the acetyl group of acetate and convert to CO2, which requires C-C cleavage.
- There is a chemical basis for the complexity of apparent oxidation of acetate units to carbon dioxide (CO2).
The Concept of the TCA (Krebs) Cycle
- The TCA cycle involves eight steps, each catalyzed by a specific enzyme.
- The acetyl group from acetyl-CoA joins the cycle by combining with oxaloacetate to make citrate.
- The cycle then regenerates oxaloacetate through the subsequent steps.
- The NADH and FADH2 produced the cycle carry electron energy for electron transport chain.
Formation of Succinyl-CoA (Alternative)
- The process involves a series of redox reactions and decarboxylations ultimately creating Succinyl-CoA.
Mechanism of the NAD+-Dependent Isocitrate Dehydrogenase
- The reaction involves a series of redox steps leading to release of CO2 and the oxidation of an alcohol to form a keto-group.
- The isocitrate dehydrogenase reaction uses Mn2+ (or Mg2+) to coordinate and facilitate the catalytic process.
Mechanism of the NAD+-Dependent α-Ketoglutarate Dehydrogenase
- This reaction catalyzes the oxidative decarboxylation of α-ketoglutarate to form succinyl-CoA using 5 cofactors: TPP, lipoic acid, CoASH, FAD&NAD+.
Mechanism of the Succinyl-CoA Synthetase
- The enzyme catalyzes substrate-level phosphorylation.
- Succinyl-CoA is phosphorylated converting GTP to GDP, or ADP to ATP.
- This is an essential process producing high-energy compounds.
Reactions Catalyzed by Succinyl-CoA Synthetase
- This enzyme catalyzes the formation and conversion of succinyl-phosphate, then a phosphoryl-His intermediate and finally product GTP through a series of intermediate steps, using GDP.
Standard Free Energy Changes (ΔG') and Physiological Free Energy Changes (ΔG) of Citric Acid Cycle Reactions
- The enzyme and reactions involved in each cycle step and their corresponding standard free energy changes values.
- Standard and physiological free-energy changes for individual TCA cycle reactions.
Major Regulatory Interactions in the TCA Cycle
- The rate of ATP hydrolysis regulates the rate of NADH oxidation.
- ADP and NADH provide feedback to control the TCA cycle.
- Isocitrate dehydrogenase, α-ketoglutarate DH, and malate DH are affected by changes in NADH concentration.
- Citrate inhibits citrate synthase.
- ADP and Ca2+ concentration activates isocitrate and α-ketoglutarate DH.
Factors Controlling the Activity of the PDC
- Feedback of NADH and acetyl-CoA.
- Production inhibition of a key reactant, pyruvate.
Anaplerotic Pathways to Replenish TCA Cycle Intermediates
- Anaplerotic reactions replenish TCA cycle intermediates.
- Key reactions like pyruvate carboxylase and transamination.
- The importance of these pathways.
The TCA Cycle Provides Intermediates for Biosynthetic Processes
- The TCA cycle provides building blocks for other metabolic processes and produces intermediates for biosynthesis.
Quiz Questions (Information, not study notes)
- Question 1: What is the ΔG°' value for hydrolysis of the thioester bond of Acetyl-CoA?
- Question 2: What is the functional group in the thiazolium ring of TPP?
- Question 3: How can the reduction of NAD+ spectroscopically be observed?
- Question 4: Why is the Krebs cycle called Tricarboxyl Acid cycle (TCA)?
- Question 5: Which enzyme/cofactor in the TCA cycle has a membrane connection? What cofactor does it use in catalysis?
- Question 6: Which enzymes from the TCA cycle are likely to function far from equilibrium under physiological conditions?
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Description
Test your knowledge on the Tricarboxylic Acid (TCA) cycle, also known as the Krebs cycle. This quiz covers key components, processes, and enzymes involved in cellular respiration, including the regeneration of oxaloacetate and the role of electron carriers. Challenge your understanding of this essential metabolic pathway in biochemistry!
