Podcast
Questions and Answers
Metabolism is the sum of the chemical processes within an organism that are necessary to sustain life.
Metabolism is the sum of the chemical processes within an organism that are necessary to sustain life.
True
ATP is not involved in energy transfer during metabolic reactions.
ATP is not involved in energy transfer during metabolic reactions.
False
Catabolic processes release energy that can be captured in ATP.
Catabolic processes release energy that can be captured in ATP.
True
Anabolism involves the breakdown of molecules to release energy.
Anabolism involves the breakdown of molecules to release energy.
Signup and view all the answers
Energy is used in organisms for activities such as muscle contraction and waste removal.
Energy is used in organisms for activities such as muscle contraction and waste removal.
Signup and view all the answers
ATP is formed through the oxidation of food fuel.
ATP is formed through the oxidation of food fuel.
Signup and view all the answers
NADH is not a significant component of metabolic pathways.
NADH is not a significant component of metabolic pathways.
Signup and view all the answers
Only proteins can be metabolized to generate ATP.
Only proteins can be metabolized to generate ATP.
Signup and view all the answers
Catabolic pathways involve the degradation of complex molecules into simple ones.
Catabolic pathways involve the degradation of complex molecules into simple ones.
Signup and view all the answers
Anabolic pathways are energy-releasing processes that synthesize complex molecules from simple ones.
Anabolic pathways are energy-releasing processes that synthesize complex molecules from simple ones.
Signup and view all the answers
NADH generated in catabolic reactions can be utilized for anabolic reactions.
NADH generated in catabolic reactions can be utilized for anabolic reactions.
Signup and view all the answers
The three types of metabolic pathways are converging, diverging, and linear.
The three types of metabolic pathways are converging, diverging, and linear.
Signup and view all the answers
The distinction between synthetic and degradative pathways allows for better control in metabolism.
The distinction between synthetic and degradative pathways allows for better control in metabolism.
Signup and view all the answers
The ATP-ADP cycle is the primary method of energy exchange in biology.
The ATP-ADP cycle is the primary method of energy exchange in biology.
Signup and view all the answers
The reaction ATP + H2O → ADP + Pi does not release energy.
The reaction ATP + H2O → ADP + Pi does not release energy.
Signup and view all the answers
NADH is commonly involved in Redox reactions.
NADH is commonly involved in Redox reactions.
Signup and view all the answers
Hydrolysis of ATP is an endergonic process.
Hydrolysis of ATP is an endergonic process.
Signup and view all the answers
Intermediary metabolism includes the conversion of food into energy.
Intermediary metabolism includes the conversion of food into energy.
Signup and view all the answers
Anabolic pathways generally produce simple organic molecules.
Anabolic pathways generally produce simple organic molecules.
Signup and view all the answers
Catabolic pathways break down energy-rich molecules into energy-depleted inorganic molecules.
Catabolic pathways break down energy-rich molecules into energy-depleted inorganic molecules.
Signup and view all the answers
Both anabolic and catabolic pathways can occur simultaneously in the same cell.
Both anabolic and catabolic pathways can occur simultaneously in the same cell.
Signup and view all the answers
Each step of a metabolic pathway is catalyzed by specific substrates.
Each step of a metabolic pathway is catalyzed by specific substrates.
Signup and view all the answers
Enzyme activity can be regulated by modifying the enzyme itself.
Enzyme activity can be regulated by modifying the enzyme itself.
Signup and view all the answers
Metabolic intermediates are energy-depleted molecules.
Metabolic intermediates are energy-depleted molecules.
Signup and view all the answers
ADP + Pi is involved in both anabolic and catabolic pathways.
ADP + Pi is involved in both anabolic and catabolic pathways.
Signup and view all the answers
Subcellular localization can affect enzyme synthesis and degradation rates.
Subcellular localization can affect enzyme synthesis and degradation rates.
Signup and view all the answers
Allosteric regulation allows for a rapid response to change in metabolic pathways.
Allosteric regulation allows for a rapid response to change in metabolic pathways.
Signup and view all the answers
The end product of a metabolic pathway can enhance the activity of the first enzyme in that pathway.
The end product of a metabolic pathway can enhance the activity of the first enzyme in that pathway.
Signup and view all the answers
Cellular homeostasis aims to keep cells in a steady-state condition.
Cellular homeostasis aims to keep cells in a steady-state condition.
Signup and view all the answers
Metabolic impairment of enzymatic activity results in the accumulation of product B.
Metabolic impairment of enzymatic activity results in the accumulation of product B.
Signup and view all the answers
Glycogenolysis is the synthesis of glycogen from glucose.
Glycogenolysis is the synthesis of glycogen from glucose.
Signup and view all the answers
Lipogenesis is the process of synthesizing triglycerides from glycerol and fatty acids.
Lipogenesis is the process of synthesizing triglycerides from glycerol and fatty acids.
Signup and view all the answers
The Kreb's cycle converts acetyl coA into carbon dioxide, water, and NADH.
The Kreb's cycle converts acetyl coA into carbon dioxide, water, and NADH.
Signup and view all the answers
Fatty acid oxidation is the synthesis of fatty acids from acetyl coA.
Fatty acid oxidation is the synthesis of fatty acids from acetyl coA.
Signup and view all the answers
Transamination is the process of degrading amino acids into amino groups and carbon backbones.
Transamination is the process of degrading amino acids into amino groups and carbon backbones.
Signup and view all the answers
Anaerobic glycolysis occurs in the presence of oxygen.
Anaerobic glycolysis occurs in the presence of oxygen.
Signup and view all the answers
Urea is a product formed during the breakdown of amino acids.
Urea is a product formed during the breakdown of amino acids.
Signup and view all the answers
Proteolysis involves the synthesis of proteins from amino acids.
Proteolysis involves the synthesis of proteins from amino acids.
Signup and view all the answers
Gluconeogenesis is the synthesis of glucose from non-carbohydrate sources.
Gluconeogenesis is the synthesis of glucose from non-carbohydrate sources.
Signup and view all the answers
Beta-oxidation is the breakdown of acetyl coA into fatty acids.
Beta-oxidation is the breakdown of acetyl coA into fatty acids.
Signup and view all the answers
Metabolism solely involves the breakdown of molecules to release energy.
Metabolism solely involves the breakdown of molecules to release energy.
Signup and view all the answers
ATP serves as the common currency for energy transfer in metabolic reactions.
ATP serves as the common currency for energy transfer in metabolic reactions.
Signup and view all the answers
Anabolic processes release energy and involve degradation of biomolecules.
Anabolic processes release energy and involve degradation of biomolecules.
Signup and view all the answers
NADH is generated from both carbohydrate and fatty acid metabolism.
NADH is generated from both carbohydrate and fatty acid metabolism.
Signup and view all the answers
Active transport of ions and molecules does not require energy.
Active transport of ions and molecules does not require energy.
Signup and view all the answers
Urea is a primary product of carbohydrate metabolism.
Urea is a primary product of carbohydrate metabolism.
Signup and view all the answers
Energy produced during catabolic reactions is utilized in anabolic processes.
Energy produced during catabolic reactions is utilized in anabolic processes.
Signup and view all the answers
Enzymatic activity can be impaired without affecting metabolic processes.
Enzymatic activity can be impaired without affecting metabolic processes.
Signup and view all the answers
Anabolic pathways involve the synthesis of complex molecules from simple ones.
Anabolic pathways involve the synthesis of complex molecules from simple ones.
Signup and view all the answers
Catabolic pathways are primarily endergonic processes.
Catabolic pathways are primarily endergonic processes.
Signup and view all the answers
The three types of metabolic pathways include converging, diverging, and cyclic.
The three types of metabolic pathways include converging, diverging, and cyclic.
Signup and view all the answers
ATP is produced exclusively during anabolic reactions.
ATP is produced exclusively during anabolic reactions.
Signup and view all the answers
NADH is a critical component produced exclusively in anabolic pathways.
NADH is a critical component produced exclusively in anabolic pathways.
Signup and view all the answers
The reverse reaction of ATP hydrolysis captures energy released from fuel compounds.
The reverse reaction of ATP hydrolysis captures energy released from fuel compounds.
Signup and view all the answers
In intermediary metabolism, carbohydrates, proteins, and lipids can be interconverted.
In intermediary metabolism, carbohydrates, proteins, and lipids can be interconverted.
Signup and view all the answers
The ATP-ADP cycle involves the transfer of electrons between NAD+ and FAD.
The ATP-ADP cycle involves the transfer of electrons between NAD+ and FAD.
Signup and view all the answers
NADH is reoxidized to NAD+ through the action of O2 in the electron transport chain.
NADH is reoxidized to NAD+ through the action of O2 in the electron transport chain.
Signup and view all the answers
The process of glycolysis involves the breakdown of glucose to release energy.
The process of glycolysis involves the breakdown of glucose to release energy.
Signup and view all the answers
Anabolic pathways generally produce complex organic molecules from simple organic molecules.
Anabolic pathways generally produce complex organic molecules from simple organic molecules.
Signup and view all the answers
The regulation of metabolic pathways can only occur through the modification of enzyme activity.
The regulation of metabolic pathways can only occur through the modification of enzyme activity.
Signup and view all the answers
Energy coupling reactions are a key link between anabolic and catabolic pathways.
Energy coupling reactions are a key link between anabolic and catabolic pathways.
Signup and view all the answers
Catabolic pathways result in the creation of energy-rich metabolites.
Catabolic pathways result in the creation of energy-rich metabolites.
Signup and view all the answers
ATP can be synthesized from metabolic intermediates such as pyruvate and acetyl CoA.
ATP can be synthesized from metabolic intermediates such as pyruvate and acetyl CoA.
Signup and view all the answers
Modification of enzymes can occur through processes such as phosphorylation.
Modification of enzymes can occur through processes such as phosphorylation.
Signup and view all the answers
Inorganic molecules like CO2 and H2O are energy-rich products of catabolic pathways.
Inorganic molecules like CO2 and H2O are energy-rich products of catabolic pathways.
Signup and view all the answers
Compartmentalization of metabolic processes allows for the simultaneous occurrence of anabolic and catabolic pathways in the same cell.
Compartmentalization of metabolic processes allows for the simultaneous occurrence of anabolic and catabolic pathways in the same cell.
Signup and view all the answers
Allosteric feedback inhibition involves the end product of a pathway activating the enzyme at the start of that pathway.
Allosteric feedback inhibition involves the end product of a pathway activating the enzyme at the start of that pathway.
Signup and view all the answers
When metabolic pathways are disturbed, changes are required to restore cellular homeostasis.
When metabolic pathways are disturbed, changes are required to restore cellular homeostasis.
Signup and view all the answers
Impaired enzyme activity can lead to accumulation of substrate A and deficiency of product B.
Impaired enzyme activity can lead to accumulation of substrate A and deficiency of product B.
Signup and view all the answers
Glycogenolysis is the process of converting glucose into glycogen.
Glycogenolysis is the process of converting glucose into glycogen.
Signup and view all the answers
Lipogenesis is the degradation of triglycerides into glycerol and fatty acids.
Lipogenesis is the degradation of triglycerides into glycerol and fatty acids.
Signup and view all the answers
The Kreb's cycle is responsible for the oxidation of acetyl coA to produce carbon dioxide, water and NADH.
The Kreb's cycle is responsible for the oxidation of acetyl coA to produce carbon dioxide, water and NADH.
Signup and view all the answers
Transamination is the process that synthesizes amino acids from metabolic intermediates.
Transamination is the process that synthesizes amino acids from metabolic intermediates.
Signup and view all the answers
Fatty acid oxidation involves the step-wise degradation of fatty acids into glycerol.
Fatty acid oxidation involves the step-wise degradation of fatty acids into glycerol.
Signup and view all the answers
Proteolysis is the breakdown of proteins into amino acids.
Proteolysis is the breakdown of proteins into amino acids.
Signup and view all the answers
Anaerobic glycolysis occurs in the absence of oxygen.
Anaerobic glycolysis occurs in the absence of oxygen.
Signup and view all the answers
Ketone bodies are synthesized from glycerol in the process of lipogenesis.
Ketone bodies are synthesized from glycerol in the process of lipogenesis.
Signup and view all the answers
Gluconeogenesis can utilize non-carbohydrate sources to generate glucose.
Gluconeogenesis can utilize non-carbohydrate sources to generate glucose.
Signup and view all the answers
Oxidative phosphorylation is involved in the synthesis of triglycerides.
Oxidative phosphorylation is involved in the synthesis of triglycerides.
Signup and view all the answers
Metabolism is solely concerned with the breakdown of complex molecules into simpler ones.
Metabolism is solely concerned with the breakdown of complex molecules into simpler ones.
Signup and view all the answers
ATP is not only produced from carbohydrate metabolism but also from the oxidation of fatty acids and proteins.
ATP is not only produced from carbohydrate metabolism but also from the oxidation of fatty acids and proteins.
Signup and view all the answers
NADH is primarily produced during anabolic processes.
NADH is primarily produced during anabolic processes.
Signup and view all the answers
Energy transfer in metabolism can occur through reactions that both release and require energy.
Energy transfer in metabolism can occur through reactions that both release and require energy.
Signup and view all the answers
Active transport mechanisms in cells use ATP as their energy source.
Active transport mechanisms in cells use ATP as their energy source.
Signup and view all the answers
The capture of energy in catabolic processes primarily results in the synthesis of NADH and ATP.
The capture of energy in catabolic processes primarily results in the synthesis of NADH and ATP.
Signup and view all the answers
Anabolic pathways primarily function to degrade energy-rich molecules into simpler forms.
Anabolic pathways primarily function to degrade energy-rich molecules into simpler forms.
Signup and view all the answers
Inherited errors of metabolism can lead to the deficiency of specific enzymes essential for metabolic processes.
Inherited errors of metabolism can lead to the deficiency of specific enzymes essential for metabolic processes.
Signup and view all the answers
The reaction Glucose + Pi produces Glucose-6-Phosphate and has a ΔG of -13.8 kJ/mol.
The reaction Glucose + Pi produces Glucose-6-Phosphate and has a ΔG of -13.8 kJ/mol.
Signup and view all the answers
NADH is oxidized back to NAD+ in the electron transport chain through a series of Redox reactions.
NADH is oxidized back to NAD+ in the electron transport chain through a series of Redox reactions.
Signup and view all the answers
ATP hydrolysis captures energy to facilitate energy-requiring reactions in a cell.
ATP hydrolysis captures energy to facilitate energy-requiring reactions in a cell.
Signup and view all the answers
Intermediary metabolism encompasses pathways that convert food into structural and functional cellular components.
Intermediary metabolism encompasses pathways that convert food into structural and functional cellular components.
Signup and view all the answers
β-oxidation is the process that synthesizes fatty acids from acetyl coA.
β-oxidation is the process that synthesizes fatty acids from acetyl coA.
Signup and view all the answers
Catabolic pathways are endergonic processes that synthesize complex molecules from simple ones.
Catabolic pathways are endergonic processes that synthesize complex molecules from simple ones.
Signup and view all the answers
Anabolic pathways can utilize ATP and NADH generated from catabolic reactions.
Anabolic pathways can utilize ATP and NADH generated from catabolic reactions.
Signup and view all the answers
Converging metabolic pathways are characterized by the synthesis of larger molecules from smaller precursors.
Converging metabolic pathways are characterized by the synthesis of larger molecules from smaller precursors.
Signup and view all the answers
Metabolic pathways can function independently without any interaction between anabolic and catabolic processes.
Metabolic pathways can function independently without any interaction between anabolic and catabolic processes.
Signup and view all the answers
The breakdown of glycogen during catabolic processes produces energy-depleted inorganic molecules.
The breakdown of glycogen during catabolic processes produces energy-depleted inorganic molecules.
Signup and view all the answers
Enzyme activity in metabolic pathways is unaffected by compartmentalization.
Enzyme activity in metabolic pathways is unaffected by compartmentalization.
Signup and view all the answers
Inorganic molecules such as CO2 and H2O are considered energy-rich compounds.
Inorganic molecules such as CO2 and H2O are considered energy-rich compounds.
Signup and view all the answers
The modification of enzyme activity by phosphorylation is a common regulatory mechanism.
The modification of enzyme activity by phosphorylation is a common regulatory mechanism.
Signup and view all the answers
Shared metabolic intermediates facilitate the connectivity between anabolic and catabolic pathways.
Shared metabolic intermediates facilitate the connectivity between anabolic and catabolic pathways.
Signup and view all the answers
Every metabolic pathway is catalyzed by multiple enzymes that perform the same function.
Every metabolic pathway is catalyzed by multiple enzymes that perform the same function.
Signup and view all the answers
Energy coupling reactions are unrelated to the ATP hydrolysis process.
Energy coupling reactions are unrelated to the ATP hydrolysis process.
Signup and view all the answers
The presence of ADP + Pi is vital for both anabolic and catabolic processes in metabolism.
The presence of ADP + Pi is vital for both anabolic and catabolic processes in metabolism.
Signup and view all the answers
Metabolic regulation does not involve the degradation of enzymes.
Metabolic regulation does not involve the degradation of enzymes.
Signup and view all the answers
Allosteric feedback inhibition allows the end product of a pathway to enhance the activity of an enzyme.
Allosteric feedback inhibition allows the end product of a pathway to enhance the activity of an enzyme.
Signup and view all the answers
The process of gluconeogenesis generates glucose from non-carbohydrate sources.
The process of gluconeogenesis generates glucose from non-carbohydrate sources.
Signup and view all the answers
Glycogenolysis refers to the degradation of glucose into pyruvate.
Glycogenolysis refers to the degradation of glucose into pyruvate.
Signup and view all the answers
Lipogenesis involves the degradation of triglycerides into glycerol and fatty acids.
Lipogenesis involves the degradation of triglycerides into glycerol and fatty acids.
Signup and view all the answers
Proteolysis is the process that synthesizes amino acids from proteins.
Proteolysis is the process that synthesizes amino acids from proteins.
Signup and view all the answers
Anaerobic glycolysis occurs independent of oxygen availability.
Anaerobic glycolysis occurs independent of oxygen availability.
Signup and view all the answers
The metabolic consequence of impaired enzyme activity can result in the deficiency of both substrate A and product B.
The metabolic consequence of impaired enzyme activity can result in the deficiency of both substrate A and product B.
Signup and view all the answers
Transamination is involved in the breakdown of fatty acids into acetyl coA.
Transamination is involved in the breakdown of fatty acids into acetyl coA.
Signup and view all the answers
Oxidative phosphorylation is responsible for extracting energy stored in NADH to generate ATP.
Oxidative phosphorylation is responsible for extracting energy stored in NADH to generate ATP.
Signup and view all the answers
The Kreb's cycle involves the conversion of fatty acids into glucose.
The Kreb's cycle involves the conversion of fatty acids into glucose.
Signup and view all the answers
Fatty acid oxidation results in the synthesis of fatty acids from acetyl coA.
Fatty acid oxidation results in the synthesis of fatty acids from acetyl coA.
Signup and view all the answers
Cellular homeostasis aims to create an unchanging environment within cells.
Cellular homeostasis aims to create an unchanging environment within cells.
Signup and view all the answers
Allosteric activators can promote the activity of enzymes in metabolic pathways.
Allosteric activators can promote the activity of enzymes in metabolic pathways.
Signup and view all the answers
A metabolic pathway can be regulated by modifying the enzyme activity at the committed step.
A metabolic pathway can be regulated by modifying the enzyme activity at the committed step.
Signup and view all the answers
Study Notes
Metabolism
- The chemical processes that sustain life in an organism.
- A complex network of reactions, many of which generate or use energy.
Cellular Functions Requiring Energy
- Active transport of ions and molecules.
- Mechanical work (muscle contraction).
- Synthesis of macromolecules.
- Waste removal.
ATP: The Energy Currency
- ATP is the molecule used to transfer energy between reactions.
- Formed through the oxidation of food fuel.
Energy Production
- NADH: A common currency in redox reactions, alongside ATP, used for energy transfer.
- Carbohydrates, fatty acids, and proteins are metabolised to generate ATP and NADH.
- Key pathways involved in generating ATP and NADH:
- Glycolysis.
- Beta-oxidation.
- TCA cycle.
- Electron transport coupled to oxidative phosphorylation.
ATP Hydrolysis and Synthesis
-
ATP + H2O ↔ ADP + Pi (-30.5 kJ/mol)
- The forward reaction releases energy.
- The reverse reaction captures energy.
- Coupled Reactions: Energy released from ATP hydrolysis can drive energy-requiring reactions.
Redox Reactions
- Many cellular reactions involve electron exchange.
- NAD+ is a coenzyme vital to redox reactions.
Intermediary Metabolism
- The processes that convert food into energy, building blocks for cells, storage molecules, and waste products.
- Includes the interconversion of carbohydrates, proteins, and lipids.
Metabolic Pathways
- Catabolic: Breakdown of molecules; complex to simple; releases energy.
- Anabolic: Synthesis of molecules; simple to complex; requires energy.
- ATP and NADH generated by catabolic pathways can be used for anabolic reactions.
Interdependence of Anabolic and Catabolic Pathways
- Generally, separate pathways exist for synthetic and degradative processes.
- Allows better control of metabolic processes.
- Linked through shared intermediates, substrates/products, enzymes and energy coupling reactions.
Regulation of Metabolic Pathways
- Enzymes: Each step in a metabolic pathway is catalyzed by a specific enzyme.
-
Regulation Methods:
- Rate of enzyme synthesis/degradation.
- Compartmentalization/subcellular localization.
- Modification by other enzymes (phosphorylation/dephosphorylation).
- Allosteric activators/inhibitors.
Allosteric Feedback Inhibition
- End product of a pathway inhibits an enzyme at the start of the pathway.
- Typically affects the first irreversible step (committed step).
- Allows rapid response to changes in cellular needs.
Cellular Homeostasis
- Maintaining a steady-state within cells.
- When disturbances occur, mechanisms are activated to return to normal conditions.
Metabolic Consequences of Impaired Enzyme Activity
-
Consequences:
- Accumulation of substrate.
- Deficiency of product.
- Diversion to alternate products.
Major Metabolic Pathways
-
Carbohydrate Metabolism:
- Glycolysis, glycogenolysis, gluconeogenesis, glycogen synthesis (glycogenesis), anaerobic glycolysis, hexose monophosphate shunt (pentose phosphate pathway).
-
Protein Metabolism:
- Amino acid synthesis, deamination, transamination, urea cycle, ketogenesis.
-
Lipid Metabolism:
- Beta-oxidation, ketogenesis, lipolysis, fatty acid synthesis, triglyceride synthesis.
-
Common Pathways:
- Citric acid cycle (Krebs cycle, tricarboxylic acid cycle), oxidative phosphorylation.
Carbohydrate Metabolism Summary
- Glycolysis: Glucose degradation to pyruvate.
- Kreb's Cycle (TCA, CAC): Conversion of acetyl CoA into carbon dioxide, water, and NADH.
- Oxidative Phosphorylation: Energy extraction from NADH to generate ATP.
- Gluconeogenesis: Synthesis of glucose from non-carbohydrate sources.
- Glycogenolysis: Glycogen degradation into glucose.
- Glycogen Synthesis (Glycogenesis): Synthesis of glycogen from glucose.
Lipid Metabolism Summary
- Lipolysis: Triglyceride degradation into glycerol and fatty acids.
- Fatty Acid Oxidation: Stepwise degradation of fatty acids into acetyl CoA.
- Fatty Acid Synthesis: Synthesis of fatty acids from acetyl CoA.
- Glycerol Synthesis: Synthesis from glycolytic intermediates.
- Lipogenesis: Synthesis of triglycerides from glycerol and fatty acids.
Protein Metabolism Summary
- Proteolysis: Protein degradation into amino acids.
- Protein Synthesis: Synthesis of proteins from amino acids.
- Amino Acid Catabolism: Degradation of amino acids into an amino group and carbon backbone.
- Glucogenic and Ketogenic Amino Acid Metabolism: Production of glucose or ketone bodies.
- Transamination: Exchange of amino groups between molecules.
- Urea Cycle: Removal of ammonia (toxic) from the body.
- Amino Acid Synthesis: Synthesis of amino acids from metabolic intermediates.
Intermediary Metabolism Summary Diagram
- A visual representation of how carbohydrate, lipid, and protein metabolism are interconnected.
- Highlights the role of glucose, pyruvate, acetyl CoA, and the Kreb's cycle in linking these pathways.
Further Resources
- Lippincott Illustrated Reviews: Biochemistry.
- Marks' Basic Medical Biochemistry: A Clinical Approach.
Metabolism
- The sum of chemical processes in an organism necessary for life
- A network of chemical reactions
- Focuses on generating or using energy
Cellular Processes that Require Energy
- Active transport of ions and molecules
- Mechanical work in muscle contraction
- Synthesis of macromolecules from simple precursors
- Waste removal
ATP as a Common Currency
- Some reactions require energy and others release energy
- Energy is transferred from one reaction to another
- ATP is the common currency for energy exchange
- Formated from the oxidation of food fuels
- Energy released from fuel compounds is captured in ATP
- ATP is the free-energy donor in most energy-requiring processes
NADH and ATP Production
- Carbohydrates, fatty acids, and proteins are metabolized to generate ATP and NADH.
- This occurs through several pathways:
- Glycolysis
- β-oxidation
- TCA cycle
- Electron transport coupled to oxidative phosphorylation
Hydrolysis and Synthesis of ATP
- ATP + H2O ↔ ADP + Pi (-30.5 kJ/mol)
- The forward reaction (hydrolysis) liberates energy for other reactions
- The reverse reaction (synthesis) captures energy released from fuel compounds
- ATP-ADP cycle is the fundamental mode of energy exchange in biology
- Most energy-requiring reactions are coupled to ATP hydrolysis
Redox Reactions
- NADH is common currency in many cellular reactions involving the exchange of electrons
- Nicotinamide Adenine Dinucleotide (NAD+) donates or accepts electrons in redox reactions
Coupled Redox Reactions
- During catabolism, hydrogen from substrates is transferred to NAD+ and FAD
- NADH and FADH2 are reoxidized by O2 in the electron transport chain located at the inner mitochondrial membrane
Intermediary Metabolism
- Metabolic processes involved in the conversion of food to energy, structural and functional components of cells, storage, and waste
- Includes the interconversion of carbohydrates, proteins, and lipids
Classification of Metabolic Pathways
-
Catabolic:
- Degradation of molecules
- Complex to simple
- Exergonic (energy-releasing)
-
Anabolic:
- Synthesis of molecules
- Simple to complex
- Endergonic (energy requiring)
- ATP and NADH generated in catabolism are used in anabolic reactions.
- Monomers released from polymeric precursors provide building blocks for synthesis
Interdependence of Anabolic and Catabolic Pathways
- Most synthetic and degradative pathways are distinct, allowing for better control.
- Pathways can occur simultaneously in separate cells.
- Linked by:
- Energy coupling reactions (ATP hydrolysis/synthesis)
- Shared metabolic intermediates
- Shared substrates/products
- Shared enzymes
Regulation of Metabolic Pathways
- Each step of a metabolic pathway is catalyzed by a specific enzyme
- Enzymes can be regulated through:
- Rate of synthesis or degradation
- Compartmentalization/subcellular localization
- Modification by another enzyme (phosphorylation/dephosphorylation)
- Allosteric activators or inhibitors
Allosteric Feedback Inhibition
- End product of a metabolic pathway inhibits the activity of an enzyme near the start, which is usually the committed step
- Allows for a fast response to change
Cellular Homeostasis
- Maintain a steady-state in cells
- Regulation of metabolic pathways is essential for cellular homeostasis.
- To return to a normal state, changes are required when steady-state is disturbed.
Consequences of Impaired Enzyme Activity
- Accumulation of substrate
- Deficiency of product
- Diversion to alternate product
Major Metabolic Pathways and Processes
- Carbohydrate metabolism: Glycolysis, glycogenolysis, gluconeogenesis, glycogen synthesis, anaerobic glycolysis, hexose monophosphate shunt
- Protein metabolism: Amino acid synthesis, deamination, transamination, urea cycle, ketogenesis
- Lipid metabolism: β-oxidation, ketogenesis, lipolysis, fatty acid synthesis, triglyceride synthesis
- Common Processes: Citric acid cycle, oxidative phosphorylation
Carbohydrate Metabolism Summary
- Glycolysis: Degradation of glucose to pyruvate
- Glycogenolysis: Degradation of glycogen into glucose
- Gluconeogenesis: Synthesis of glucose from non-carbohydrate sources
- Kreb's Cycle (TCA cycle): Conversion of acetyl CoA into CO2, H2O, and NADH
- Oxidative Phosphorylation: Extraction of energy in NADH to generate ATP
Lipid Metabolism Summary
- Lipolysis: Degradation of triglycerides into glycerol and fatty acids
- Fatty Acid Oxidation: Step-wise degradation of fatty acids into acetyl CoA
- Fatty Acid Synthesis: Synthesis of fatty acids from acetyl CoA
- Lipogenesis: Synthesis of triglycerides from glycerol and fatty acids
- Glycerol Synthesis: Synthesis from glycolytic intermediates
- Ketone bodies: Synthesized from fatty acids
- Glycogen synthesis: Synthesis of glycogen from glucose (from food sources)
Protein Metabolism Summary
- Proteolysis: Degradation of protein into amino acids
- Protein Synthesis: Synthesis of proteins from amino acids
- Amino Acid Catabolism: Degradation of amino acids into amino group and carbon backbone
- Transamination: Transfer of amino group to a keto acid
- Urea Cycle: Removal of excess nitrogen from the amino group
- Glucogenic Amino Acid Metabolism: Used to synthesize glucose through gluconeogenesis
- Ketogenic Amino Acid Metabolism: Used to synthesize ketone bodies
- Amino Acid Synthesis: Synthesize of amino acids from metabolic intermediates
Intermediary Metabolism Diagram
- Shows interconnectedness of carbohydrate, lipid, and protein metabolism
- Includes:
- Glycogenolysis
- Lipogenesis
- Lipolysis
- Proteolysis
- Protein synthesis
- Gluconeogenesis
- Glycerol synthesis
- Fatty acid synthesis
- Fatty acid oxidation
- Transamination
- Urea cycle
Further Resources
- Lippincott Illustrated Reviews: Biochemistry
- Marks' Basic Medical Biochemistry: A Clinical Approach
Metabolism
- Metabolism is the sum of all chemical processes that occur within an organism to sustain life
- It involves a highly integrated network of chemical reactions
- Many reactions are concerned with generating or using energy
Importance of energy for organisms
- Active transport of ions and molecules
- Performance of mechanical work such as muscle contraction
- Synthesis of macromolecules from simple precursors
- Waste removal
ATP: Energy Currency
- ATP is the common currency in the energy exchange economy
- Reactions that require energy are coupled with energy releasing reactions so that energy can be transferred
- Adenosine Triphosphate (ATP) is formed from the oxidation of food fuel
- Energy released from food fuel is captured in ATP
- ATP is the free-energy donor in most energy-requiring processes
NADH: Redox reactions
- Many cellular reactions involve the exchange of electrons
- NADH (Nicotinamide Adenine Dinucleotide) is a common currency in redox reactions
Key Metabolic Pathways and Processes
- Carbohydrate metabolism: Glycolysis, glycogenolysis, gluconeogenesis, glycogen synthesis
- Protein metabolism: Amino acid synthesis, deamination, transamination, urea cycle, ketogenesis
- Lipid Metabolism: beta−oxidation, ketogenesis, lipolysis, fatty acid synthesis, triglyceride synthesis
- Common pathways: Citric acid cycle (Krebs cycle, tricarboxylic acid cycle), oxidative phosphorylation
Cellular Regulation of Metabolic pathways
- Each step is catalyzed by a specific enzyme
- Enzyme activity is regulated in multiple ways:
- Rate of enzyme synthesis/degradation
- Compartmentalization/ subcellular localization
- Modification by another enzyme (e.g. phosphorylation and dephosphorylation)
- Allosteric activators/inhibitors
- Allosteric feedback inhibition is a common mechanism of regulation where the end product of a pathway inhibits an early enzyme in the pathway. This usually occurs at the first irreversible step (committed step)
- Allosteric regulation allows for a rapid response to change
- Cellular homeostasis is maintained through the regulation of metabolic pathways
- When the steady-state is disturbed, changes need to be made to return conditions back to normal
Consequences of Impaired Enzyme Activity
- Accumulation of substrate A
- Deficiency of product B
- Diversion to alternate product C
Interdependence of Anabolic and Catabolic Pathways
- Anabolic pathways: Synthesis of molecules; Simple to complex; Endergonic (energy requiring)
- Catabolic pathways: Degradation of molecules; Complex to simple; Exergonic (energy releasing)
- ATP and NADH generated in catabolism can be used for anabolic reactions
- Distinctive pathways allow for more efficient control
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your understanding of metabolism and the role of ATP in energy production. This quiz covers cellular functions, energy currency, and key metabolic pathways like glycolysis and the TCA cycle. Explore how organisms sustain life through complex biochemical reactions.
