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Chapter 8 An Introduction to Metabolism - Coggle Diagram
Chapter 8 An Introduction to Metabolism
An Organism’s Metabolism: All chemical reactions in an organism
Metabolic Pathways
Catabolic pathways → break down molecules → release energy (ex: cellular respiration)
Anabolic pathways → build molecules → require energy (ex: protein synthesis)
Relationship: Energy from catabolism drives anabolism
Energy Transformations
Kinetic energy → motion
Potential energy → stored energy
Chemical energy → potential energy in molecules
Thermodynamics
First Law → energy conservation
Second Law → entropy increases
Organisms are open systems → exchange energy/matter with surroundings
The Free Energy Change of a Reaction (ΔG): Portion of system’s energy available to do work
Free Energy (ΔG = ΔH – TΔS)
ΔH = enthalpy (total energy)
ΔS = entropy
T = temperature (K)
Spontaneous vs. Nonspontaneous
Spontaneous → ΔG < 0 (energy released)
Nonspontaneous → ΔG > 0 (requires energy)
Equilibrium
Maximum stability → no net change
Living cells never at equilibrium (constant flow of materials)
Exergonic vs. Endergonic
Exergonic → releases energy (ex: cellular respiration)
Endergonic → requires energy (ex: photosynthesis)
ATP Powers Cellular Work: ATP = energy currency of the cell
Structure
Adenine + ribose + 3 phosphate groups
Phosphoanhydride bonds store energy
ATP Hydrolysis
ATP → ADP + Pi + energy
Energy used to perform cellular work
Cellular Work Types
Chemical → drives endergonic reactions
Transport → pumps substances across membranes
Mechanical → movement (ex: motor proteins)
ATP Regeneration
From ADP + Pi using energy from catabolism
ATP cycle → links catabolic & anabolic pathways
Enzymes Speed Up Metabolic Reactions: Biological catalysts that lower activation energy
How Enzymes Work
Substrate binds to enzyme’s active site
Induced fit model
Catalytic cycle → substrate → products → enzyme unchanged
Factors Affecting Enzyme Activity
Temperature
pH
Cofactors & coenzymes
Inhibitors (competitive vs. noncompetitive)
Regulation of Enzyme Activity
Allosteric regulation
Feedback inhibition → prevents overproduction
Examples
Digestive enzymes (amylase, protease)
Metabolic enzymes (ATP synthase)
Connections to Cellular Respiration & Photosynthesis
Metabolism links energy flow and matter cycling
Catabolic → respiration (exergonic)
Anabolic → photosynthesis (endergonic
Energy coupling maintains homeostasis