7/20/2015. Energy. Lecture 4 Outline (Ch. 8) Energy. What is Energy?

Transcription

1 Lecture 4 Outline (Ch. 8) I. Overview II. Thermodynamics III. Metabolism and IV. Cellular (ATP) and coupled reactions V. Enzymes and Regulation VI. Summary What is? Where does our (humans) energy come from? Types of : - Kinetic = energy of movement (heat, light) - Potential = stored energy (chemical) Thermodynamics study of energy transformation in a system Potential energy can be converted to kinetic energy (& vice versa) 1

2 Thermodynamics Laws of Thermodynamics: Explain the characteristics of energy 1 st Law: is conserved is not created or destroyed can be converted (Chemical Heat) 2 nd Law: During conversions, amount of useful energy decreases No process is 100% efficient Entropy (measure of disorder) is increased is converted from more ordered to less ordered forms Metabolism Metabolism chemical conversions in an organism Metabolic reactions: All chemical reactions in organism Catabolic = breaks down molecules Anabolic = builds up molecules Two Types of Metabolic Reactions Chemical Reaction: Process that makes and breaks chemical bonds + Reactants + Products Two Types of : 1) Exergonic = releases energy 2) Endergonic = requires energy 2

3 Metabolism and Metabolic reactions: Chemical reactions in organism Cells convert molecules chemically using cellular energy. Glucose CO 2 + H 2 0 -ΔG release energy spontaneous Exergonic reaction CO 2 + H 2 0 Glucose +ΔG (or 0) intake energy non-spontaneous Endergonic reaction Recall, which is more ordered, polymers or monomers? Which has more energy, polymers or monomers? What type of energy are we talking about here? What might the reactant(s) be for the red graph, polymers or monomers? 3

4 Cellular - ATP ATP = adenosine triphosphate ribose, adenine, 3 phosphates last (terminal) phosphate - removable Be able to diagram ATP! Cellular - ATP ATP hydrolyzed to ADP Exergonic ATP + H 2 O ADP + P i released ATP can be regenerated, using energy in food Fill in missing terms in the boxes on the diagram below: 4

5 : Like home offices tend toward disorder Endergonic energy taken in; Exergonic energy given off Exergonic Endergonic Self-Check Reaction Exergonic or Endergonic? Breaking down starches to sugars Building proteins Digesting Fats Activation : required to jumpstart a chemical reaction Must overcome repulsion of molecules due to negative charged electrons Nucleus Repel Nucleus Activation Nucleus Repel Nucleus Activation 5

6 Exergonic Reaction: Reactants have more energy than products Activation energy: Make sure molecules collide Downhill reaction Diagram this reaction on a graph where free-energy is on the Y-axis and reaction progress (time) is on the x-axis. water + CO 2 sugar + O 2 Enzymes and Enzymes lower activation energy only for specific reactions cell chooses which reactions proceed! enzymes: Cannot make rxns go that wouldn t otherwise Cannot change endergonic into exergonic rxns Do speed up rxns that would occur anyway 6

7 Enzymes enzyme specific to substrate (molecule being bound) active site part of enzyme binds substrate binding tightens fit induced fit How might enzymes lower E A? catalytic part of enzyme: converts reactant(s) to product(s) Enzymes Enzymes control rate of chemical reaction, catalyst maltase enzyme for maltose breakdown -ase enzyme Enzymes inhibitors: Competitive Non-competitive binds & blocks active site binds allosteric site alters conformation Drug blocks HIV enzyme at the active site 7

8 Think about what type of biomolecules enzymes are and what we have discussed about enzymes. a. List factors that can modify enzyme function. b. What effect(s) can each of these factors have on enzyme function? A, B, and C are intermediates in the enzymatic pathway below required to make D; 1, 2, and 3 are enzymes that catalyze each reaction: A B C D E If this was instead a shoe factory, leather (A) is cut (1) to make parts (B), which are sewn together (2) to make shoes (C). These are packaged for shipping as D. If the factory drops shoes and now wants to make leather backpacks (E) Where should the process for shoes be shut down? In a cell, if an excess of chemical D arises, where should synthesis be regulated? What step? Explain. 8