Ch1 Chemical and Physical Foundations PDF

Living Organisms Exist in a Dynamic Steady State, Never at Equilibrium with Their Surroundings small molecules, macromolecules, and supramolecular complexes are continuously synthesized and broken down living cells maintain themselves in a dynamic steady state distant from equil...

Living Organisms Exist in a Dynamic Steady State, Never at Equilibrium with Their Surroundings small molecules, macromolecules, and supramolecular complexes are continuously synthesized and broken down living cells maintain themselves in a dynamic steady state distant from equilibrium maintaining steady state requires the constant investment of energy Thermodynamic system Organisms Transform Energy and Matter from Their Surroundings system = all the constituent reactants and products, the solvent that contains them, and the immediate atmosphere universe = system + its surroundings types of systems: – isolated = system exchanges neither matter nor energy with its surroundings – closed system = system exchanges energy but not matter with its surroundings – open system = system exchanges both energy and matter with its surroundings  Question A living organism is a(n): A. isolated system. B. closed system. C. open system. D. universe.  Question Response A living organism is a(n): C. open system. A living organism is an open system; it exchanges both matter and energy with its surroundings. Energy Transformation in Living Organisms first law of thermodynamics: in any physical or chemical change, the total amount of energy in the universe remains constant, although the form of the energy may change  Principle Living organisms exist in a dynamic steady state, never at equilibrium with their surroundings. Following the laws of thermodynamics, living organisms extract energy from their surroundings and employ it to maintain homeostasis and do useful work. Essentially all of the energy obtained by a cell comes from the flow of electrons, driven by sunlight or by metabolic redox reactions.  Extracting Energy from the Surroundings photoautotrophs: chemotrophs:  Oxidation-Reduction Reactions autotrophs and heterotrophs participate in global cycles of O2 and CO2, driven by sunlight, making these two groups interdependent oxidation-reduction reactions = one reactant is oxidized (loses electrons) as another is reduced (gains electrons) – describes reactions involved in electron flow Creating and Maintaining Order Requires Work and Energy second law of thermodynamics: randomness in the universe is constantly increasing entropy, S = represents the randomness or disorder of the components of a chemical system  entropy, S = represents the randomness or disorder enthalpy, H = heat content, reflecting the number and kinds of bonds free energy, G, of a closed system = H – TS, where H represents enthalpy, T represents absolute temperature, and S represents entropy free-energy change, ∆G = ∆H − T∆S where ∆H is negative for a reaction that releases heat, and ∆S is positive for a reaction that increases the system’s randomness spontaneous reactions occur when ∆G is negative  Topic Question for presentation Ch1. What is Δ G of Diamond to Graphite reaction ? Explain if it is a spontaneous reaction.  Question Which of these is a reflection of the total energy change in a chemical reaction, a measure of the number and kinds of bonds that are made and broken? A. ∆G B. ∆H C. ∆S D. ∆T  Question , Response Which of these is a reflection of the total energy change in a chemical reaction, a measure of the number and kinds of bonds that are made and broken? B. ∆H The enthalpy change, ∆H, reflects the kinds and numbers of chemical bonds and noncovalent interactions broken and formed.  Coupling Reactions energy-requiring (endergonic) reactions are often coupled to reactions that release free energy (exergonic) the breakage of phosphoanhydride bonds in ATP is highly exergonic