This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: CHAPTER 8 AN I N TRODUCT ION TO M ETABOL ISM Bioenergetics: The Laws of Thermodynamics 8.2.1 The chemistry of life is organized into metabolic pathways Bioenergetics the study of how energy flows through living organisms I. Metabolism manages the material and energy resources of the cell 1. Uptake of matter and energy energy through food or other substances usually come in the wrong form 2. Conversion to usable form 3. Synthesis (combining) of cellular materials 4. Elimination of waste products I I. Two types of metabolic pathways ( begins with a specific molecule: each step of the pathway is catalyzed by a specific enzyme) : catabolic pathways and anabolic pathways A. Catabolism - degradation, releases energy- by breaking down complex molecules to simpler compounds a. Major pathway = cellular respiration sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water (downhill) B. Anabolism - synthesis, consumes energy a. sometimes called biosynthetic pathways b. Opposite from catabolism (uphill) These pathways are going to be about breaking things (deriving energy from it) up or building things (energy requiring pathway) I I I. Organisms transfer energy A. Energy is the capacity to do work ** Review types of energy 1. Potential energy/positional energy stored 2. Kinetic energy/motion energy of motion *These two energies are inconvertible: potential energy can become kinetic energy and vice versa Heat or thermal energy is kinetic energy associated with the random movement of atoms or molecules Chemical energy potential energy available for release in a chemical reaction B. Energy transfers are subject to the laws of thermodynamics (see fig 8.3) 1. Fi rst Law of Thermodynamics energy can be transferred and transformed, but it cannot be created or destroyed (i.e. the energy of the universe is constant) 2. Second Law of Thermodynamics every energy transfer or transformation makes the universe more disordered; every energy transfer youre going to lose energy to a source that we or any organism cannot tap into (i.e. the energy of chaos; every process increases entropy) 3. Entropy (S) quantitative measure of disorder that is proportional to randomness; we dont have to worry about it causing a direct effect on us except were losing energy to it; impossible to measure the entropy but you can measure how much you lost C. Thermodynamics can determine whether or not a chemical reaction will occur in the cell, and how much energy it will consume or release 1. Free energy and spontaneous reactions (see fig 8.5) a. Free energy (G) portion of energy available to do work; its the difference between the total energy (enthalpy) and the energy not available to do work (entropy) (TS) b. Total energy (H) is the total energy of a system *G (free energy) = H (total energy of system) T (temperature) S (entropy) *We have to think about the molecules/situation in terms of stability: the more unstable, the more orderly the...
View Full Document
This note was uploaded on 03/19/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Fall '07 term at LSU.
- Fall '07