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Metabolism and Energy

Metabolism and Energy. Chapter 3.1 McGraw-Hill Ryerson Biology 12 (2011). Metabolism. Metabolism : sum of all chemical reactions that occur in the cell Metabolic pathway : sequential series of chemical reactions in living cells; each reaction is catalyzed by an enzyme. Metabolism.

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Metabolism and Energy

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  1. Metabolism and Energy Chapter 3.1 McGraw-Hill Ryerson Biology 12 (2011)

  2. Metabolism • Metabolism: sum of all chemical reactions that occur in the cell • Metabolic pathway: sequential series of chemical reactions in living cells; each reaction is catalyzed by an enzyme

  3. Metabolism • 2 ways to work with molecules: • Catabolism: process of breaking down compounds into smaller molecules to release energy • Anabolism: process of using energy to build large molecules from smaller molecules

  4. Energy • Kinetic Energy: energy of motion • Potential Energy: stored energy Bond Energy: energy required to break or form a chemical bond

  5. Thermodynamics • Thermodynamics is the study of transfer and transformation of thermal energy (heat) • Applies to a system and its surroundingsSystem: whatever object(s) are being studied in an environment • Can be open or closed • Open means that system and surroundings exchange matter with each other (uncontained) • Closed means that the system can only exchange matter and materials within itself (contained)

  6. Thermodynamics • Thermodynamics is the study of transfer and transformation of thermal energy (heat) • 1st Law: Energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another • 2nd Law: During any process, the universe tends toward disorder Entropy: measure of disorder

  7. Thermodynamics • Free energy: energy from a chemical reaction that is available for doing work Both chemical bonding and heat have a significant influence on a molecule (chemical bonding reduces disorder; heat increases it) The net amount of energy actually available to break and form other bonds is free energy

  8. Thermodynamics • Gibbs Free energy: • All chemical systems tend naturally toward states of minimum Gibbs free energy Where: ΔG = Change in Gibbs Free Energy Δ H = Change in Enthalpy (heat content) T = Temperature in Kelvins Δ S = Entropy (can think of as randomness)

  9. Thermodynamics • Endergonic: chemical reaction that requires energy (ΔG is positive) • Exergonic: chemical reaction that releases energy (ΔG is negative)

  10. Thermodynamics • Hydrolysis of ATP to ADP is highly exergonic

  11. Coupled Reactions • Cells use ATP to drive endergonic reactions • Hydrolysis of ATP releases energy but if uncoupled will merely be lost as heat • Thus ATP is coupled to fuel other reactions in the cell

  12. Electron Carriers • Redox reactions are coupled reaction • Influence flow of energy in biological systems • Electrons that pass from one atom to another carry energy, reducing power • Reduced form of a molecule is always at a higher energy level than oxidized form • Electron Carriers: compounds that pick up electrons from energy-rich compounds and donate them to low-energy compounds

  13. Homework • Pg. 121 #2, 4, 5, 8

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