Enzymes are Proteins!

2. Enzymes are Proteins! • Proteins contain the elements: C, H, O, N • The monomers of proteins are Amino acids

3. Characteristics of Enzymes • Facilitate or catalyze chemical reactions in cells • Speed them up • By lowering the activation energy (the energy needed to start the reaction) • W/O enzymes, chemical reactions would occur too slowly at the temperatures found in organisms to sustain life processes

5. A Catalyst Analogy* • You are at the American Museum of Natural History (because you are a science nerd and like to look at Dinosaur Bones • You need to get to Babo (because you are a big fan of Iron Chef) • What are your transportation options? *Analogy provided thanks to Ms.Walker

6. A Catalyst Analogy* • You can walk… • If you walk like a New Yorker – about 1 block a minute – you would walk over 80 blocks – so an hour and 20 minutes. • Longer if you walk like a Livingston High School student on their way to class • You can take the C from 81st to West 4th St • Once the train arrives – about 15-17 minutes. • Less time if you can transfer to the A *Analogy provided thanks to Ms.Walker

7. The train is the “enzyme” that catalyzes your transportation *Analogy provided thanks to Ms.Walker

8. Characteristics of Enzymes • 3D shape (tertiary or quaternary) confers specificity to the substrate upon which it binds to facilitate the reaction • Many enzymes are named after the substrate on which they act and end in –ase • Sucrase (enzyme) acts upon sucrose (substrate)

9. Substrate = Reactant Molecule • Active site= specific binding site on the enzyme for the substrate to bind to

10. Lock and Key Model An exact fit between enzyme and substrate; The enzyme works with one specific substrate

11. Induced Fit Model Enzyme can react with similar substrate molecules to produce the same product; The active site of enzyme undergoes shape change

14. How Enzymes Work Enzymes bind to the substrate and weaken the chemical bonds, so less energy is needed for the reaction to proceed

15. Factors that affect Enzymes • Enzymes are affected by their environment • There are optimal conditions for every enzyme • Optimal conditions = optimal performance • Deviations= Denaturization = Loss of Function • Substrate & Enzyme Concentration • Higher temperatures • Changes in salt concentrations & pH

16. Substrate Concentration • Enzymes must “bump into” substrate molecules • More substrate =more collisions =more enzymes being used=more activity • At some point activity levels off because all possible enzymes are already in use

17. Enzyme Concentration • Again, enzymes must “bump into” substrate molecules • More enzymes= more collisions = more activity • At some point all substrates are being broken down and so increasing enzymes no longer increases activity

18. pH • Every enzyme has an “optimal” pH • a pH at which the enzyme functions most effectively • Most enzymes in the human body work best between pH 6-8 (near neutral)

19. Temperature • Every enzyme has an optimal temperature • Most enzymes in the human body work best between 35-40˚C (near normal body temps) • Increase in Temp = increase in molecular collisions = increase in enzyme activity • However, this only hold true to a point! • Too much heat can denature the protein and slow activity down or cause loss of function

20. Energy and Chemical Reactions

21. What is Energy? • Energy • The ability to do work • Potential • Stored Energy • Chemical Energy = potential energy of molecules • Kinetic • Energy of doing work (motion) • Heat • Energy associated with the movement of molecules

23. Life Depends on Energy Conversion Thermodynamics =The study of energy conversions • Two laws govern energy conversion: • First Law of Thermodynamics • The law of energy conservation • Energy can be transferred and transformed, but not created or destroyed • Second Law of Thermodynamics • Energy conversions reduce order (increase disorder) • Amount of disorder = Entropy

24. Chemical Reactions • Chemical reactions are involved when energy conversions occur • Atoms are rearranged • Law of Conservation of Matter • Matter is neither created nor destroyed • The sum of all chemical reactions in an organism • Metabolism • Chemical reactions either store or release energy

25. Endothermic and Exothermic Reactions Chemical reactions either store or release energy • Endergonic Reactions = Endothermic Reactions • Store energy • Yield products high in potential energy • Photosynthesis • Exergonic Reactions = Exothermic Reactions • Release energy • Potential energy is high in the reactants • Cellular Respiration

26. Comparing Endothermic and Exothermic Reactions

27. Coupled Reactions • Many reactions use the energy released from exothermic reactions to drive or fuel endothermic reactions • These are called “Coupled Reactions” • ATP Regeneration is the main example in cells • The usable energy released by most exothermic reactions is stored in ATP • The energy used in most endothermic reactions comes from ATP

28. Cellular work is sustained because ATP is a renewable resource that cells can regenerate