2. Lecture 5 Outline (Ch. 8) I.Energy and Metabolism II.Thermodynamics A. 1 st Law – conservation of energy B. 2 nd Law - entropy III.Free Energy IV.Chemical Reactions V.Cellular Energy - ATP VI. Enzymes A. Function B. Regulation VII. Lecture Concepts

3. What is Energy? The capacity to cause change Types of Energy: - Kinetic Energy = energy of movement Energy - thermal - Potential = stored energy- chemical

4. Metabolism Metabolism – all the chemical conversions in an organism

5. Potential energy can be converted to kinetic energy (& vice versa) Potential Energy Kinetic Energy Thermodynamics Thermodynamics – study of energy transformation in a system

6. Laws of Thermodynamics: Laws of Thermodynamics: Explain the characteristics of energy 1 st Law: Energy is conserved Energy is not created or destroyed Energy can be converted (Chemical  Heat) 2 nd Law: During conversions, amount of useful energy decreases No process is 100% efficient Thermodynamics Energy is converted from more useful to less useful forms Entropy (measure of disorder) is increased

7. Metabolic reactions: Chemical reactions in organism Anabolic = builds up molecules Metabolism Two Types of Metabolic Reactions: Catabolic = breaks down molecules

8. Chemical Reaction: Process that makes and breaks chemical bonds + Reactants + Products Two Types of Chemical Reactions: 1) Exergonic = releases energy 2) Endergonic = requires energy Free Energy

9. Energy of a system Gibb’s free energy = energy available to cause change difference in free energy (ΔG) - predict if rxn will occur If ΔG (+) or 0, If ΔG (-), -process non-spontaneous -consume energy -process spontaneous -release energy system – moves to more stable (lower energy)

10. Chemical Reactions Exergonic reaction Endergonic reaction -ΔG-ΔG release free energy spontaneous +ΔG (or 0) intake free energy non-spontaneous Glucose  CO 2 + H 2 0CO 2 + H 2 0  Glucose

11. Chemical Reactions: Like home offices – tend toward disorder Chemical Reactions

12. Chemical Reactions: Endergonic – energy required to complete reaction Exergonic – energy given off Exergonic Endergonic Chemical Reactions

13. 2. Endergonic reactions: “Energy in” Products have more energy than reactants Requires influx of energy » 1. Exergonic reactions: “Energy out” Reactants have more energy than products Reaction releases energy Chemical Reactions

14. Activation Energy: Energy required to “jumpstart” a chemical reaction Must overcome repulsion of molecules due to negative charged electrons Nucleus Repel Nucleus Repel Nucleus Activation Energy Activation Energy Chemical Reactions

15. Exergonic Reaction: –Reactants have more energy than products But will sugar spontaneously burst into flames? Activation energy: Make sugar and O 2 molecules collide Chemical Reactions “Downhill” reactions sugar + O 2 water + CO 2

16. Cellular Energy - ATP ATP = adenosine triphosphate ribose, adenine, 3 phosphates last (terminal) phosphate - removable

17. ATP hydrolyzed to ADP Exergonic ΔG = -7.3 kcal/mol ATP + H 2 OADP + P i Energy released, coupled to another rxn (endergonic) Cellular Energy - ATP

18. endergonic exergonic Cellular Energy - ATP by coupling, overall rxn still exergonic

19. ATP regenerated ΔG = +7.3 kcal/mol cells power ATP generation by coupling to exergonic rxns - cellular respiration Cellular Energy - ATP

20. Enzymes Enzymes – rate of chemical rxn sucrase – enzyme sucrose breakdown sucrase – catalyst-speed up rxn, not consumed “-ase” enzyme break bonds reactants -contort molecule -unstable -need energy input form bonds products -energy given off

21. Enzymes energy input Energy of activation (E A ) reactants – absorb energy - E A E A from heat rxn proceeds Exergonic – energy given off rxn rate – due to reaching E A E A from ambient heat?- usually insufficient This is GOOD!

22. Enzymes lower E A only for specific rxns cell chooses which rxns go forward This is GOOD! enzymes:-don’t change ΔG -do speed up rxn would occur anyway -don’t make endergonic exergonic

23. Enzymes enzyme – specific to substrate active site – part of enzyme -substrate binding tightens fit – induced fit form enzyme-substrate complex catalytic part of enzyme: converts reactant(s) to product(s)

24. Enzymes substrate(s) enter Enzymes lowers E A by: products formed -template orientation -stress bonds -microenvironment enzyme reused Enzyme activity affected by: substrate conc., temp., pH

25. Enzymes inhibitors: normal competitive inhibition competitive – bind active site non-competitive – binds other site – alters conformation Drug – blocks HIV enzyme - competitive inhibition non-competitive inhibition

26. Feedback Inhibition: Enzymes Like your furnace: Room is cold Room is warm Heat kicks on Detector activated Heat stays on warmer

27. Self-Check EndergonicExergonic energy used/given off catabolic/anabolic spontaneous/not ΔG (+)/ (-) ATP made/hydrolyzed downhill/uphill Enzyme regulationDescription Competitive inhibition Non-competitive inhibition Feedback inhibition

28. Lecture 5 concepts -Define metabolism, thermodynamics, free energy -Describe the 1 st and 2 nd laws of thermodynamics and how they relate to chemical reactions -Explain the terms exergonic and endergonic in terms of free energy and chemical reactions -Draw a graph of free energy for exothermic and endothermic chemical reactions; label products, reactants, & E A -Discuss the structure and purpose of ATP -Draw and describe how enzymes affect chemical reactions -List factors that affect enzyme activity -Write out a list of new terminology and provide descriptions