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12.1.2 - Pages 9-16

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  1. Front
    ATP synthesis reaction
    Back
    ADP + Pi → ATP requires energy input
  2. Front
    Standard free energy change of ATP formation
    Back
    ΔG°' = +30.5 kJ/mol
  3. Front
    Energy requirement for ATP synthesis
    Back
    ATP must be formed using another energy source
  4. Front
    Substrate-level phosphorylation
    Back
    Formation of ATP by direct transfer of a phosphate group from a substrate to ADP
  5. Front
    Electron transport chain requirement in substrate-level phosphorylation
    Back
    Not required
  6. Front
    Examples of substrate-level phosphorylation substrates
    Back
    Phosphoenolpyruvate, 1,3-bisphosphoglycerate, and succinyl-CoA
  7. Front
    Example reaction of substrate-level phosphorylation
    Back
    PEP + ADP → pyruvate + ATP
  8. Front
    Location of substrate-level phosphorylation
    Back
    Glycolysis and TCA cycle
  9. Front
    Oxidative phosphorylation
    Back
    Main ATP production system in humans
  10. Front
    First step of oxidative phosphorylation
    Back
    Fuel molecules are oxidized
  11. Front
    NAD⁺ reduction in oxidative phosphorylation
    Back
    NAD⁺ becomes NADH
  12. Front
    Role of NADH in oxidative phosphorylation
    Back
    Carries electrons to the electron transport chain
  13. Front
    Final electron acceptor in oxidative phosphorylation
    Back
    Oxygen
  14. Front
    Proton gradient formation
    Back
    Occurs across the mitochondrial membrane during electron transport
  15. Front
    ATP synthase function
    Back
    Synthesizes ATP using the proton gradient
  16. Front
    Location of oxidative phosphorylation
    Back
    Mitochondria
  17. Front
    ATP yield from oxidative phosphorylation
    Back
    Produces approximately 90% of ATP in aerobic cells
  18. Front
    Photosynthetic phosphorylation
    Back
    ATP production driven by light energy
  19. Front
    Organisms performing photosynthetic phosphorylation
    Back
    Plants, algae, and cyanobacteria
  20. Front
    Energy source for photosynthetic phosphorylation
    Back
    Light
  21. Front
    Mechanism of photosynthetic phosphorylation
    Back
    Light drives electron flow creating a proton gradient used to synthesize ATP
  22. Front
    Relevance of photosynthetic phosphorylation to humans
    Back
    Not relevant for human metabolism
  23. Front
    Redox reactions
    Back
    Oxidation and reduction reactions that drive metabolism
  24. Front
    Oxidation
    Back
    Loss of electrons
  25. Front
    Reduction
    Back
    Gain of electrons
  26. Front
    Oxidation in metabolism
    Back
    Fuel molecules lose electrons during breakdown
  27. Front
    Reduction in metabolism
    Back
    Electron carriers gain electrons
  28. Front
    Example of reduction
    Back
    NAD⁺ gains electrons to form NADH
  29. Front
    Catabolism as an oxidative process
    Back
    Fuel molecules lose electrons during breakdown
  30. Front
    Example of catabolic oxidation
    Back
    Glucose is oxidized to carbon dioxide
  31. Front
    Electron carriers in catabolism
    Back
    NAD⁺ and FAD accept electrons
  32. Front
    NAD⁺ function
    Back
    Acts as an electron collector in metabolism
  33. Front
    Reduction of NAD⁺
    Back
    NAD⁺ + 2e⁻ + H⁺ → NADH
  34. Front
    Role of NADH
    Back
    Delivers electrons to the electron transport chain
  35. Front
    Anabolism as a reductive process
    Back
    Building molecules requires electron input
  36. Front
    Electron donor in anabolism
    Back
    NADPH
  37. Front
    Example of reductive biosynthesis
    Back
    Fatty acid synthesis requires NADPH
  38. Front
    Catabolism electron carrier
    Back
    Produces NADH
  39. Front
    Anabolism electron carrier
    Back
    Uses NADPH
  40. Front
    Convergent pathways
    Back
    Pathways where many different molecules are broken down into a few common intermediates
  41. Front
    Example of carbohydrate convergence
    Back
    Glucose → pyruvate → acetyl-CoA
  42. Front
    Example of fat convergence
    Back
    Fatty acids → acetyl-CoA
  43. Front
    Example of protein convergence
    Back
    Amino acids → acetyl-CoA or TCA intermediates
  44. Front
    Major convergence molecule
    Back
    Acetyl-CoA
  45. Front
    Role of acetyl-CoA
    Back
    Central metabolic hub that enters the citric acid cycle
  46. Front
    Citric acid cycle
    Back
    Metabolic pathway that processes acetyl-CoA
  47. Front
    Divergent pathways
    Back
    Pathways where a few starting molecules produce many different products
  48. Front
    Example of divergence from acetyl-CoA
    Back
    Fatty acids, cholesterol, steroid hormones, and phospholipids
  49. Front
    Amphibolic pathways
    Back
    Pathways that function in both catabolism and anabolism
  50. Front
    Example of amphibolic pathway
    Back
    Citric acid cycle
  51. Front
    Catabolic role of citric acid cycle
    Back
    Breaks down acetyl-CoA
  52. Front
    Anabolic role of citric acid cycle
    Back
    Provides intermediates for synthesis of amino acids, glucose, and fatty acids
  53. Front
    Metabolic pathway
    Back
    A sequence of enzyme-catalyzed reactions converting substrates to products
  54. Front
    Role of enzymes in pathways
    Back
    Each step is catalyzed by a specific enzyme
  55. Front
    Multienzyme complexes
    Back
    Groups of physically connected enzymes that catalyze sequential reactions
  56. Front
    Example of multienzyme complex
    Back
    Pyruvate dehydrogenase complex
  57. Front
    Function of pyruvate dehydrogenase complex
    Back
    Converts pyruvate to acetyl-CoA
  58. Front
    Example of multienzyme complex
    Back
    Fatty acid synthase
  59. Front
    Function of fatty acid synthase
    Back
    Synthesizes fatty acids
  60. Front
    Example of multienzyme system
    Back
    Pyrimidine synthesis enzymes
  61. Front
    Function of pyrimidine synthesis enzymes
    Back
    Produce nucleotide bases
  62. Front
    Advantages of multienzyme complexes
    Back
    Increased speed, substrate channeling, reduced diffusion loss, and improved regulation
  63. Front
    Substrate channeling
    Back
    Direct transfer of intermediates between enzymes without diffusion
  64. Front
    Compartmentation
    Back
    Separation of metabolic pathways into different cellular locations
  65. Front
    Cytosol location
    Back
    Fluid portion of the cell where certain pathways occur
  66. Front
    Cytosolic pathways
    Back
    Glycolysis, pentose phosphate pathway, and fatty acid synthesis
  67. Front
    Mitochondrial matrix location
    Back
    Interior of mitochondria where specific pathways occur
  68. Front
    Mitochondrial pathways
    Back
    Citric acid cycle, oxidative phosphorylation, beta-oxidation, and ketone body formation
  69. Front
    Pathways requiring multiple compartments
    Back
    Gluconeogenesis and urea cycle
  70. Front
    Purpose of compartmentation
    Back
    Prevents pathway interference, allows regulation, and maintains distinct chemical environments
  71. Front
    Example of compartment separation
    Back
    Fatty acid synthesis and fatty acid breakdown occur in different compartments
  72. Front
    Irreversible reactions
    Back
    Reactions with large negative ΔG that cannot easily run in reverse
  73. Front
    Role of irreversible reactions
    Back
    Serve as key regulatory points in metabolic pathways
  74. Front
    Non-reversibility of pathways
    Back
    Anabolic and catabolic pathways are not simple reversals of each other
  75. Front
    Bypassing irreversible steps
    Back
    Alternate enzymes are used in opposing pathways
  76. Front
    Example of pathway bypass
    Back
    Glycolysis irreversible steps are bypassed in gluconeogenesis
  77. Front
    Purpose of bypass reactions
    Back
    Prevents futile cycling
  78. Front
    Futile cycling
    Back
    Simultaneous forward and reverse pathway activity wasting energy
  79. Front
    Regulation of metabolism
    Back
    Control of metabolic pathways to maintain balance and efficiency
  80. Front
    Methods of metabolic regulation
    Back
    Enzyme amount, enzyme activity, and substrate availability
  81. Front
    Control of enzyme amount
    Back
    Regulation through gene transcription affecting enzyme levels
  82. Front
    Effect of increased enzyme concentration
    Back
    Increases pathway rate
  83. Front
    Control of enzyme activity
    Back
    Regulation through activation or inhibition of enzymes
  84. Front
    Mechanisms of enzyme activity control
    Back
    Allosteric regulation and covalent modification
  85. Front
    Control of substrate availability
    Back
    Availability of substrate determines whether reactions proceed
  86. Front
    Example of substrate control
    Back
    Low glucose levels slow glycolysis
  87. Front
    Feedback inhibition
    Back
    End product of a pathway inhibits an earlier step
  88. Front
    Mechanism of feedback inhibition
    Back
    Product binds to and inhibits an upstream enzyme
  89. Front
    Purpose of feedback inhibition
    Back
    Prevents overproduction of end products
  90. Front
    Allosteric regulation
    Back
    Regulation of enzyme activity by binding at a site other than the active site
  91. Front
    Effect of allosteric binding
    Back
    Changes enzyme shape and activity
  92. Front
    Phosphofructokinase (PFK)
    Back
    Key regulatory enzyme in glycolysis
  93. Front
    Activators of PFK
    Back
    AMP and fructose-2,6-bisphosphate
  94. Front
    Inhibitors of PFK
    Back
    ATP and citrate
  95. Front
    Energy status effect on PFK
    Back
    High energy inhibits glycolysis, low energy stimulates it
  96. Front
    Fructose-1,6-bisphosphatase
    Back
    Key regulatory enzyme in gluconeogenesis
  97. Front
    Activator of fructose-1,6-bisphosphatase
    Back
    Citrate
  98. Front
    Inhibitors of fructose-1,6-bisphosphatase
    Back
    AMP and fructose-2,6-bisphosphate
  99. Front
    Reciprocal regulation of glycolysis and gluconeogenesis
    Back
    When one pathway is active, the other is suppressed
  100. Front
    Covalent modification
    Back
    Regulation of enzyme activity by addition or removal of chemical groups
  101. Front
    Common covalent modification
    Back
    Phosphorylation
  102. Front
    Phosphorylation
    Back
    Addition of a phosphate group to a protein
  103. Front
    Protein kinase
    Back
    Enzyme that catalyzes phosphorylation using ATP
  104. Front
    Phosphorylation reaction
    Back
    Protein + ATP → phosphorylated protein + ADP
  105. Front
    Protein phosphatase
    Back
    Enzyme that removes phosphate groups from proteins
  106. Front
    Dephosphorylation reaction
    Back
    Phosphorylated protein + H₂O → protein + Pi
  107. Front
    Effect of phosphorylation on enzymes
    Back
    Can activate or inhibit enzyme activity
  108. Front
    Processes regulated by phosphorylation
    Back
    Glycogen metabolism, glycolysis, gluconeogenesis, and hormone signaling
  109. Front
    Hormonal control of metabolism
    Back
    Hormones regulate pathways through signaling cascades
  110. Front
    Examples of metabolic hormones
    Back
    Insulin, glucagon, and epinephrine
  111. Front
    Principle of metabolism
    Back
    Occurs through enzyme-controlled pathways
  112. Front
    Catabolic outputs
    Back
    ATP, NADH, and FADH₂
  113. Front
    Anabolic inputs
    Back
    ATP and NADPH
  114. Front
    ATP role
    Back
    Primary energy currency of the cell
  115. Front
    Properties of metabolic pathways
    Back
    Interconnected, compartmentalized, and highly regulated
  116. Front
    Main regulatory mechanisms
    Back
    Allosteric regulation, covalent modification, and feedback inhibition
  117. Front
    Additional regulation methods
    Back
    Control of enzyme amount and substrate availability
  118. Front
    Catabolism characteristics
    Back
    Oxidative, ATP-producing, and convergent
  119. Front
    Anabolism characteristics
    Back
    Reductive, ATP- and NADPH-consuming, and divergent
  120. Front
    Types of ATP production
    Back
    Oxidative phosphorylation and substrate-level phosphorylation
  121. Front
    Key metabolic regulators
    Back
    Allosteric effectors, phosphorylation, gene expression, and feedback inhibition

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