Biol 111: Topic 6 - Metabolism PDF

Biol 111: Topic 6 Metabolism Biol 111, J. Toxopeus https://www.youtube.com/watch?v=nRq6N5NGD1U 1 Review: Topic 6 Learning Objectives 2  Lecture Guide 6...

Biol 111: Topic 6 Metabolism Biol 111, J. Toxopeus https://www.youtube.com/watch?v=nRq6N5NGD1U 1 Review: Topic 6 Learning Objectives 2  Lecture Guide 6 section 1 Metabolism Overview Metabolism is the totality of an organism’s chemical reactions An organism’s metabolism transforms matter and energy Metabolism is an emergent property of life that arises from interactions between molecules within the cell Biol 111, J. Toxopeus 3  Metabolism Overview The chemistry of life is organized into metabolic pathways A metabolic pathway begins with a specific reactant molecule(s) and ends with a product(s) Each step is catalyzed by a specific enzyme (metabolism is enzyme-mediated) regulation of metabolic pathways usually controlled by one of the enzymes Biol 111, J. Toxopeus 4  Metabolism Overview There are two broad categories of metabolic processes: Anabolism: building substances (e.g. protein synthesis) Catabolism: breaking down substances (e.g. digestion) Anabolism Catabolism Biol 111, J. Toxopeus 5  Metabolism Overview Catabolic pathways release energy by breaking down complex molecules into simpler compounds Example: Cell respiration involves the breakdown of glucose in the presence of oxygen to form CO2, water, and ATP Biol 111, J. Toxopeus 6  Metabolism Overview Anabolic pathways consume energy to build complex molecules from simpler ones Example: Photosynthesis involves the synthesis of glucose from CO2 and water using energy from light Biol 111, J. Toxopeus 7  Lecture Guide 6 section 2 Thermodynamics Overview Thermodynamics is the study of energy transformations, a useful way to understand metabolism Biol 111, J. Toxopeus 8  Lecture Guide 6 section 2A Types of Energy Kinetic energy is energy associated with motion ○ Thermal energy (heat) is kinetic energy associated with random movement of atoms or molecules Potential energy is energy that matter possesses because of its location or structure ○ Chemical energy is potential energy available for release in a chemical reaction (e.g. glucose) Biol 111, J. Toxopeus 9  Lecture Guide 6 section 2B First Law of Thermodynamics First Law of Thermodynamics: Energy can be transferred and transformed, but it cannot be created or destroyed a.k.a. The principle of conservation of energy Biol 111, J. Toxopeus 10  First Law of Thermodynamics in biological terms Cells convert energy from one form into another, for example: energy in photons (light) into energy in chemical bonds energy in chemical bonds into kinetic energy (movement) Biol 111, J. Toxopeus 11  Lecture Guide 6 section 2C Second Law of Thermodynamics Second Law of Thermodynamics: Every energy transfer or transformation (e.g. making/breaking covalent bonds) increases the entropy (disorder) of the universe Biol 111, J. Toxopeus 12  Second Law of Thermodynamics There is a universal tendency toward disorder (entropy) Energy input is required to do work to maintain order in living systems Biol 111, J. Toxopeus 13  Second Law of Thermodynamics in biological terms Cells create ordered structures (e.g. proteins) from less ordered materials (e.g. amino acids) Organisms also replace ordered forms of matter and energy with less ordered forms (e.g. digestion of proteins from food) Biol 111, J. Toxopeus 14  Gibbs Free Energy (G) – energy available to do work Example of a reaction with a negative ΔG, or ΔG < 0 Energy in reactant(s) Gibbs free energy of the reaction Energy in product(s) Also sometimes Time or Reaction Progress Biol 111, J. Toxopeus 18  Gibbs Free Energy in biological terms Reactions that result in increased disorder generally have a negative ΔG (i.e. catabolic reactions tend to have a ΔG < 0) Biol 111, J. Toxopeus 19  Lecture Guide 6 section 3B Endergonic and Exergonic Reactions ΔG is a measure of whether a reaction will proceed: 1. If ΔG < 0, the reaction is spontaneous (favours products) 2. If ΔG = 0, the reaction is at equilibrium 3. If ΔG > 0, the reaction is non-spontaneous (favours reactants) Biol 111, J. Toxopeus 20