Lesson 01-1 - Metabolism and Energy PDF

UNIT #2: METABOLISM Meta = “change” Bolism = “to throw” “…to throw a change…” Key Learning Objectives Demonstrate an understanding of the role that metabolic processes play in living and non-living systems on Earth Describe how the products of photosynthesis and cellular respiration are made...

UNIT #2: METABOLISM Meta = “change” Bolism = “to throw” “…to throw a change…” Key Learning Objectives Demonstrate an understanding of the role that metabolic processes play in living and non-living systems on Earth Describe how the products of photosynthesis and cellular respiration are made and consumed Understand how chemical changes and energy transformations occur in metabolic pathways METABOLISM AND ENERGY What is Metabolism? METABOLISM refers to all the chemical reactions that change or transform matter and energy in cells These reactions occur in step-by-step sequences called METABOLIC PATHWAYS Enzymes catalyze each step, converting a substrate into a product; the product then becomes the substrate for the next step in the pathway  Catabolism The process by which complex molecules are broken down into smaller, simpler molecules Cata: down ; Bolism: to throw Catabolism: “to throw down” … “to break down” Two key results of catabolism: Stored energy is released. Complex molecules are broken into smaller molecules. Anabolism The process by which complex molecules are synthesized from simpler ones Ana: up; Bolism: to throw Anabolism: “to throw up” … “to build up” Two key results of anabolism: Energy is stored in the form of chemical bonds. Simple molecules are linked together to form larger molecules. Catabolism vs Anabolism  Metabolism = Anabolism + Catabolism Since metabolism represents the sum of all reactions in a living system (organism), it consists of two processes that are constantly occurring simultaneously: catabolism and anabolism Three possibilities result from the interaction of these two processes: – When anabolism exceeds catabolism, growth or weight gain occurs. More energy is stored than released. – When catabolism exceeds anabolism, weight loss occurs. More energy is released than stored. – When catabolism and anabolism occur at the same rate, a state of dynamic equilibrium occurs. Although both breaking down and building up occurs, there is no net change. Energy All forms of energy can be classified as kinetic energy or potential energy Kinetic Energy – Energy possessed by moving objects (ex. Heart muscle contracting) – Many forms (thermal/heat, mechanical, electromagnetic) Potential Energy – Stored energy – Forms include gravitational and chemical Kinetic vs Potential Energy The Laws of Thermodynamics Thermodynamics: the science that studies the transfer and transformation of thermal energy (heat) Biological systems are considered to be open systems, able to exchange matter and energy between them and their surroundings The First Law of Thermodynamics Energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another Aka Law of Conservation of Energy The Second Law of Thermodynamics During any process, the universe tends towards disorder, or entropy increases Entropy: a measure of disorder Energy transformations convert molecules from more ordered (less stable) to less ordered (more stable) states Ex. Overtime, the room becomes more disorganized. Entropy has increased in this room. An input of energy is needed to restore the original ordered condition of the room! Free Energy Free Energy: the energy from a chemical reaction that is available for doing work Aka Gibbs’ Free Energy ∆G = ∆ H- T ∆ S G = Free Energy T = Temperature H = Enthalpy S = Entropy (energy in chemical bonds) Exergonic/Exothermic Reaction Exergonic: a chemical reaction that releases energy Products have LESS energy than reactants Energy is RELEASED ∆G < 0 Endergonic/Endothermic Reaction Endergonic: a chemical reaction that requires energy Products have MORE energy than reactants Energy is ABSORBED ∆G >0 Comparison Glucose + Pi → G6P + Glucose + ATP → G6P H20 + ADP Delta G = +13.8KJ/mol Delta G= -16.7KJ/mol Not favourable, won’t Favourable, addition of happen ATP gives direction and allows the reaction to proceed Bond Energy Bond energy: energy required to break (or form) a chemical bond When a chemical bond forms between two atoms, energy is RELEASED Energy is required and increases the potential energy of the molecule Ie., gluose+glucose→glycogen When a chemical bond is broken, energy is ABSORBED Energy is released and is able to do work Hydrolysis of ATP→ADP+Pi  ATP: Adenosine Triphosphate ATP can store a lot of energy The hydrolysis of ATP releases energy. In this case, ATP is split into ADP (adenosine diphosphate) and an inorganic phosphate (Pi) Energy is stored in phosphate bonds! Coupled Reactions Cells use ATP to drive ENDERGONIC reactions Hydrolysis of ATP is coupled so that the energy released assists endergonic reactions to proceed With energy: Electron Carriers Electron carriers are compounds that pick up electrons from energy rich compounds and donate them to low energy rich compounds Coupled with redox reactions Cofactors include NADH, FADH etc. NAD+/NADH NAD+ is an oxidizing agent accepting electrons from other molecules so that it becomes reduced When it is reduced it is in the form of NADH, which is a reducing agent because it can donate electrons Oxidizing Agent Reducing Agent Reduced Form Oxidized form FADH/FAD+ Reducing Agent Oxidized form Oxidizing Agent Reduced Form  Oxidizing agent Reducing agent