Chapter 3.1 McGraw-Hill Ryerson Biology 12 (2011) 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 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

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

Thermodynamics Thermodynamics is the study of transfer and transformation of thermal energy (heat) Applies to a system and its surroundings System: 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)

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

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

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)

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

Thermodynamics Hydrolysis of ATP to ADP is highly exergonic

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

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

Homework Pg. 121 #2, 4, 5, 8