1. Lecture 4 Outline (Ch. 8) I.Energy Overview II.Thermodynamics III.Metabolism and Chemical Reactions IV.Cellular Energy (ATP) and coupled reactions V.Enzymes and Regulation VI. Summary

2. What is Energy? Energy Types of Energy: - Kinetic Energy = energy of movement (heat, light) - Potential = stored energy (chemical) Where does our (humans) energy come from?

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

4. 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 ordered to less ordered forms Entropy (measure of disorder) is increased

5. Metabolism Metabolism – chemical conversions in an organism Metabolic reactions: All chemical reactions in organism Anabolic = builds up molecules Two Types of Metabolic Reactions Catabolic = breaks down molecules

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

7. Metabolism and Energy Cells convert molecules chemically using cellular energy. Metabolic reactions: Chemical reactions in organism

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

9. Chemical Reactions What might the reactant(s) be for the red graph, polymers or monomers? Recall, which is more ordered, polymers or monomers? Which has more energy, polymers or monomers? What type of energy are we talking about here?

10. Cellular Energy - ATP ATP = adenosine triphosphate ribose, adenine, 3 phosphates last (terminal) phosphate - removable Be able to diagram ATP!

11. ATP hydrolyzed to ADP Exergonic ATP + H 2 OADP + P i Energy released Cellular Energy - ATP ATP can be regenerated, using energy in food

12. Fill in missing terms in the boxes on the diagram below:

13. Chemical Reactions: Like home offices – tend toward disorder Chemical Reactions Endergonic – energy taken in; Exergonic – energy given off Exergonic Endergonic

14. Self-Check ReactionExergonic or Endergonic? Breaking down starches to sugars Building proteins Digesting Fats

15. 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

16. Exergonic Reaction: –Reactants have more energy than products Activation energy: Make sure molecules collide Chemical Reactions “Downhill” reaction

17. Diagram this reaction on a graph where free-energy is on the Y-axis and reaction progress (time) is on the x-axis. Chemical Reactions sugar + O 2 water + CO 2 Energy

18. Chemical Reactions and Enzymes Enzymes lower activation energy only for specific reactions cell chooses which reactions proceed! enzymes:Cannot make rxns go that wouldn’t otherwise Do speed up rxns that would occur anyway Cannot change endergonic into exergonic rxns

19. Enzymes enzyme – specific to substrate (molecule being bound) active site – part of enzyme – binds substrate binding tightens fit – induced fit catalytic part of enzyme: converts reactant(s) to product(s) How might enzymes lower E A ?

20. Enzymes Enzymes – control rate of chemical reaction, catalyst maltase – enzyme for maltose breakdown“-ase” enzyme

21. Enzymes inhibitors: Drug – blocks HIV enzyme at the active site binds & blocks active site binds allosteric site – alters conformation CompetitiveNon-competitive

22. 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?

23. 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 1 2 3 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.