Chapter 8 - Chapter 8 An Introduction to Metabolism Concept 8.1 An organism's metabolism transforms matter and energy subject to the laws of

Chapter 8 An Introduction to Metabolism Concept 8.1 An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics. • The chemistry of life is organized into metabolic pathways • Metabolism – the totality of an organism’s chemical reactions. o Uptake of matter o Conversion to usable form o Synthesis of cellular materials o Elimination of waste products • A metabolic pathway begins with a specific molecule, which is then altered is a series of defined steps, resulting in a certain product. o Each step of the pathway is catalyzed by a specific enzyme . • Metabolism – Pathway Types: o Catabolic : pathways involved in degradation.  Release energy by breaking down complex molecules to simpler ones. o Anabolic : pathways involved in synthesis.  Consume energy to build complicated molecules from simpler ones. Sometimes called biosynthetic pathways. • Organisms transfer energy o Energy is the capacity to do work. o Potential energy – energy that an object possesses because of its structure or position o Kinetic energy – the relative motion of objects. o Energy transfers by organisms are subject to two laws of thermodynamics  First Law of Thermodynamics: energy can be transferred and transformed, but it cannot be destroyed (i.e. energy of the universe is constant) • Known as the principle of conservation of energy. -- Second Law of Thermodynamics : states that every energy transfer or transformation makes the universe more disordered (ex. Every process increases entropy) - Entropy (S) – the quantitative measure of disorder or randomness ***The free-energy change of a reaction tells us whether or not the reaction occurs spontaneously >>>Free energy and spontaneous reactions - Free energy (G) is the portion of energy available to do work - ^G = ^H – T^S -