tailieunhanh - Lecture Biology - Chapter 6: Metabolism: Energy and enzymes

After studying this chapter, you should be able to accomplish the following outcomes: State and apply two energy laws to energy transformations, give reasons why ATP is called the energy currency in cells, give examples to show how ATP hydrolysis is coupled to energy-requiring reactions, describe a metabolic pathway and how they function,. | Metabolism: Energy and Enzymes Chapter 6 Flow of Energy Energy: the capacity to do work -kinetic energy: the energy of motion -potential energy: stored energy Energy can take many forms: mechanical electric current heat light Flow of Energy Most forms of energy can be converted to heat energy. Heat energy is measured in kilocalories. One calorie = the amount of heat required to raise the temp of water by 1oC 1 kilocalorie (kcal) = 1000 calories Flow of Energy Potential energy stored in chemical bonds can be transferred from one molecule to another by way of electrons. oxidation: loss of electrons reduction: gain of electrons redox reactions are coupled to each other. Laws of Thermodynamics First Law of Thermodynamics – energy cannot be created or destroyed -energy can only be converted from one form to another For example: sunlight energy chemical energy photosynthesis Laws of Thermodynamics Second Law of Thermodynamics: disorder is more likely than order entropy: disorder in the universe The 2nd Law of Thermodynamics states that entropy is always increasing. Laws of Thermodynamics Free energy: the energy available to do work -denoted by the symbol G (Gibb’s free energy) enthalpy: energy contained in a molecule’s chemical bonds free energy = enthalpy – (entropy x temp.) G = H - TS Laws of Thermodynamics Chemical reactions can create changes in free energy: DG = DH - T DS When products contain more free energy than reactants – DG is positive. When reactants contain more free energy than products – DG is negative. Laws of Thermodynamics Chemical reactions can be described by the transfer of energy that occurs: endergonic reaction: a reaction requiring an input of energy - DG is positive exergonic reaction: a reaction that releases free energy - DG is negative Laws of Thermodynamics Most reactions require some energy to get started. activation energy: extra energy needed to get a reaction started -destabilizes existing . | Metabolism: Energy and Enzymes Chapter 6 Flow of Energy Energy: the capacity to do work -kinetic energy: the energy of motion -potential energy: stored energy Energy can take many forms: mechanical electric current heat light Flow of Energy Most forms of energy can be converted to heat energy. Heat energy is measured in kilocalories. One calorie = the amount of heat required to raise the temp of water by 1oC 1 kilocalorie (kcal) = 1000 calories Flow of Energy Potential energy stored in chemical bonds can be transferred from one molecule to another by way of electrons. oxidation: loss of electrons reduction: gain of electrons redox reactions are coupled to each other. Laws of Thermodynamics First Law of Thermodynamics – energy cannot be created or destroyed -energy can only be converted from one form to another For example: sunlight energy chemical energy photosynthesis Laws of Thermodynamics Second Law of Thermodynamics: disorder is more likely than order .