ENERGY, THERMODYNAMICS and ENZYMES

1. ENERGY, THERMODYNAMICS and ENZYMES © 2012 Pearson Education, Inc.

2. 5.10 Cells transform energy as they perform work All organisms require nutrients = raw building blocks Most common elements: C, H, O, N, P, S These materials are acquired by living organisms, broken down, recycled, and built back up again into new organic compounds as needed All organisms require energy for basic life functions – any characteristic to define life ultimately requires energy!! © 2012 Pearson Education, Inc.

3. 5.10 Cells transform energy as they perform work All organisms require energy for basic life functions – any characteristic to define life ultimately requires energy!! Energy = capacity to cause change or to perform work. Two kinds of energy: Kinetic energy is the energy of motion. Potential energy is energy that matter possesses as a result of its location or structure. Heat = thermal energy Free energy = portion of energy available to do work, Chemical energy = potential energy available in bonds within molecules and released in a chemical reaction. Most relevant energy to living organisms © 2012 Pearson Education, Inc.

4. Figure 5.10 Waste products Energy conversion Fuel Heatenergy Carbon dioxide Gasoline   Combustion Kinetic energyof movement Water Oxygen Energy conversion in a car Heatenergy Cellular respiration Glucose Carbon dioxide   ATP ATP Oxygen Water Energy for cellular work Energy conversion in a cell

5. Thermodynamics = study of energy transformations First law of thermodynamics = energy in the universe is constant Implication: Biological organisms cannot produce energy - only convert forms of energy Ultimate source of energy for all ecosystems = sun (solar energy) Second law of thermodynamics = energy conversions increase the disorder (entropy) of the universe. No energy transformations are 100 % efficient With every energy transformation some sable energy lost as heat Energy transformations are one-way street Biological organisms require constant supply of energy to maintain order!! © 2012 Pearson Education, Inc.

6. Metabolism = total of an organism’s chemical reactions • Two general types of metabolic processes: • Synthetic (anabolic) • Photosynthesis • Convert solar to chemical energy • Dehydration reactions • Convert nutrients to biomolecules • Decomposition (catabolic) • Cellular respiration • Release free energy in organic compounds • Hydrolysis • Release energy © 2012 Pearson Education, Inc.

7. Spontaneous chemical reactions are exergonic Chemical reactions are either Exergonic reactions release energy. These reactions release the energy in covalent bonds of the reactants. Cellular respiration An endergonic reaction requires an input of energy; products contain more chemical/potential energy Photosynthesis Energy coupling = energy released from exergonic reactions drive endergonic reactions!! © 2012 Pearson Education, Inc.

8. Figure 5.11A Reactants Amount ofenergyreleased Potential energy of molecules Energy Products

9. Figure 5.11B Products Amount ofenergyrequired Potential energy of molecules Energy Reactants

10. Cells need energy to perform work!! There are three main types of cellular work: chemical mechanical transport ATP drives all three of these types of work. © 2012 Pearson Education, Inc.

11. ATP = Adenosine triphosphate Triphosphate ATP: Adenosine Phosphategroup P P P Adenine Ribose © 2012 Pearson Education, Inc.

12. Figure 5.12A_s2 Triphosphate ATP: Adenosine Phosphategroup P P P Adenine Ribose H2O Hydrolysis Energy P P P Diphosphate ADP: Adenosine

13. ATP drives cellular work Hydrolysis of ATP releases energy by transferring phosphate from ATP to some other molecule Phosphorylation = transfer of a phosphate functional group from one molecule to another © 2012 Pearson Education, Inc.

14. Figure 5.12B Mechanical work Transport work Chemical work ATP ATP ATP Solute P Motorprotein P P Reactants Membrane protein P P P Product Molecule formed Solute transported Protein filament moved ADP ADP ADP P P P

15. How Does Cell Regenerate ATP? ATP = renewable source of energy for the cell. ATP cycle = energy released in an exergonic reaction is used in an endergonic reaction to generate ATP. ATP Phosphorylation Hydrolysis Energy fromexergonicreactions Energy forendergonicreactions ADP P © 2012 Pearson Education, Inc.

16. HOW ENZYMES FUNCTION © 2012 Pearson Education, Inc.

17. Enzymes = Organic catalysts Increase RATE of chemical reaction by decreasingactivation energy (EA). EA = energy barrier must be overcome before any chemical reaction can begin. Activationenergy barrier Enzyme Activationenergy barrierreduced byenzyme Reactant Reactant Energy Energy Products Products Without enzyme With enzyme © 2012 Pearson Education, Inc. Animation: How Enzymes Work

18. a b Energy Reactants c Products Progress of the reaction Enzymes Only Increase RATE of reaction, NOT the energy Level of reactants or products!!!

19. A specific enzyme catalyzes each cellular reaction An enzyme Is specific in substrate(s) it binds And reaction it catalyzes Substrate = reactant A substrate binds at enzyme active site. Enzymes are specific because their active site fits only specific substrate molecules Active site is result of 3D folding of protein © 2012 Pearson Education, Inc.

20. 1 2 3 4 Catalytic cycle of an enzyme Enzyme availablewith empty activesite Active site Substrate(sucrose) Substrate bindsto enzyme withinduced fit Enzyme(sucrase) Glucose Fructose H2O Products arereleased Substrate isconverted toproducts

21. Factors that Effect Enzyme-Catalyzed Reactions For every enzyme, there are optimal conditions under which it is most effective. Temperature pH Substrate Concentration Enzyme Concentration Cofactors/coenzymes Inhibitors © 2012 Pearson Education, Inc.

22. Factors that Affect Enzyme-Catalyzed Reactions Many enzymes require nonprotein helpers called cofactors, which bind to the active site and function in catalysis. Inorganic molecules Coenzymes Organic molecule that acts as cofactor © 2012 Pearson Education, Inc.

23. Enzyme Concentration

24. Substrate Concentration

25. Temperature - affects molecular motion

26. pH

27. Enzyme inhibitors can regulate enzyme activity Inhibitor = chemical that interferes with an enzyme’s activity. Competitive inhibitors block substrates from entering the active site and reduce an enzyme’s productivity. Noncompetitive inhibitors bind to the enzyme somewhere other than the active site, change the shape of the active site, and prevent the substrate from binding. Substrate Active site Enzyme Allosteric site Normal binding of substrate Competitiveinhibitor Noncompetitiveinhibitor Enzyme inhibition © 2012 Pearson Education, Inc.

28. Enzyme inhibitors are important in regulating cell metabolism. Feedback inhibition = product of metabolic pathway acts as an inhibitor of one of the enzymes in the pathway Feedback inhibition Enzyme 1 Enzyme 2 Enzyme 3 B D A C Reaction 2 Reaction 3 Reaction 1 Product Startingmolecule

29. Describe the fluid mosaic structure of cell membranes. Describe the diverse functions of membrane proteins. Relate the structure of phospholipid molecules to the structure and properties of cell membranes. Define diffusion and describe the process of passive transport. You should now be able to © 2012 Pearson Education, Inc.

30. Explain how osmosis can be defined as the diffusion of water across a membrane. Distinguish between hypertonic, hypotonic, and isotonic solutions. Explain how transport proteins facilitate diffusion. Distinguish between exocytosis, endocytosis, phagocytosis, pinocytosis, and receptor-mediated endocytosis. You should now be able to © 2012 Pearson Education, Inc.

31. Define and compare kinetic energy, potential energy, chemical energy, and heat. Define the two laws of thermodynamics and explain how they relate to biological systems. Define and compare endergonic and exergonic reactions. Explain how cells use cellular respiration and energy coupling to survive. You should now be able to © 2012 Pearson Education, Inc.

32. You should now be able to Explain how ATP functions as an energy shuttle. Explain how enzymes speed up chemical reactions. Explain how competitive and noncompetitive inhibitors alter an enzyme’s activity. Explain how certain drugs, pesticides, and poisons can affect enzymes. © 2012 Pearson Education, Inc.

33. Table 5.UN05

34. Figure 5.UN06 Rate of reaction 6 7 8 0 10 1 2 4 5 3 9 pH