Chapter 4 Enzymes and metabolism part I Outline Energy in Biological Systems What is work? What is energy? Chemical Reactions Enzymes Energy Ability to do work And Work requires energy Ways to think about work Transport Mechanical Chemical Reactions Now ways to think about energy Kinetic Potential Energy of movement (work) Stored energy Energy can be converted from one form to another AND Energy can be transferred between molecules through chemical reactions. Potential energy is STORED in covalent bonds. Free energy is a measurement of this STORED ENERGY. Exergonic and Endergonic reactions Lets apply the terms exergonic and endergonic to these concepts of stored versus released energy! Exergonic Reaction Releases energy Potential energy Kinetic energy In class demo. of a spontaneous exergonic reaction Hopefully not! Now try answering these questions based on demonstration 1. This reaction demonstrated a low or high activation energy? LOW!!! 2. This reaction stores or releases free energy? RELEASES Endergonic: stores energy exergonic endergonic Where does the activation energy come from for the bodys many reactions? Reactions may get directly coupled: _________ reactions push __________ reactions forward! Exergonicendergonic FILL IN THE BLANKS! ATP+H 2 0 ADP + Pi + H + +energy Most biological reactions are reversible Keep in mind: the activation energy most be low for reversible reactions to occur. How does the body manage to lower the activation energy of so many chemical pathways in the body? ENZYMES!!!!!!!!! The End