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Labs, labs and more labs. 1. Potato Demo 2. Enzymes Lab

Labs, labs and more labs. 1. Potato Demo 2. Enzymes Lab Objective: explain how an enzyme can be altered by pH, temp and concentration HW: free responses due tomorrow Lab due Mon 10/31 Ch. 8 reading guide Journals due 11/3 - last reading is Aquaporins on 10/31.

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Labs, labs and more labs. 1. Potato Demo 2. Enzymes Lab

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  1. Labs, labs and more labs. 1. Potato Demo 2. Enzymes Lab Objective: explain how an enzyme can be altered by pH, temp and concentration HW: free responses due tomorrow Lab due Mon 10/31 Ch. 8 reading guide Journals due 11/3 - last reading is Aquaporins on 10/31

  2. Take out your chapter 8 reading guide. Turn in free responses and 4 packets. 1. Talk about yesterday's lab results 2. Chapter 8 Objective: explain how an enzyme can be altered by pH, temp and concentration HW: Ch. 8 reading guide Lab due Mon 10/31 Journals due 11/3 - last reading is Aquaporins on 10/31

  3. Metabolism: totality of an organism's chemical reactions

  4. Catabolic Pathway Anabolic Pathway ·Consume energy to build complicated molecules from simpler ones ·Biosynthetic pathways ·Ex: protein synthesis ·Release energy by breaking down complex molecules into simpler compounds ·Breakdown pathways ·Ex: cellular respiration

  5. Anabolic: ·building up ·using energy from catabolic reactions Catabolic: ·breaking down ·energy released to power anabolic reactions

  6. capacity to cause change energy associated with relative motion of objects kinetic energy associated with the random movement of atoms or molecules energy that matter possesses because of its location or structure potential energy available for release in a chemical reaction Energy Kinetic Energy Heat/Thermal Energy Potential Energy Chemical Energy

  7. Thermodynamics: study of energy transformations that occur in a collection of matter

  8. First Law of Thermodynamics: Energy of the universe is constant Energy can be transferred and transformed, but it cannot be created or destroyed. Principle of conservation of energy

  9. Second Law of Thermodynamics: Every energy transfer of transformation increases the randomness (entropy) of the universe. For a process to occur spontaneously (without the input of energy), it must increase the entropy of the universe Ex: car rusting, water flowing

  10. Light Energy Heat Energy Heat Energy Heat Energy Heat Energy Heat Energy

  11. Free Energy: portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell ( G) G = H - T S Processes with negative G are spontaneous Must give up: Enthalpy (heat) Order Both Every spontaneous process decreases the system's free energy Harnessed to perform work

  12. Free energy represents the difference between the free energy of the final state and the free energy of the initial state Measure of a system's instability - tendency to change to a more stable state When moving toward equilibrium, a process is spontaneous and can perform work

  13. Exergonic: Net release of free energy Spontaneous G is negative Greater the decrease, the greater the amount of work that can be done

  14. Endergonic: Absorbs free energy G is positive Nonspontaneous G is the quantity of energy needed to drive the reaction

  15. Exergonic: ·release free energy ·- G Endergonic: ·absorbs free energy ·+ G

  16. Take out your Ch. 8 reading guides and your 2 enzyme labs. 1. Ch. 8 2. Discuss labs - time to work on labs 3. Required Readings discussion Objective: explain how structure is related to function in regards to enzymes HW: Ch. 8 reading guide Lab due Mon 10/31 Journals due 11/3 - last reading is Aquaporins on 10/31

  17. Closed systems eventually reach equilibrium and can then do no work

  18. A cell that has reached equilibrium is dead! Constant flow of materials in and out

  19. Glucose and Oxygen CO2 and Water

  20. Energy coupling: using an exergonic process to power an endergonic one

  21. Adenosine Triphosphate (ATP)

  22. To do work, the phosphate group is added to an intermediate molecule

  23. Phosphorylated: a molecule that has had a phosphate group added to it · Key to energy coupling - a phosphorylated intermediate, which is more reactive than the original unphosphorylated molecule

  24. Exergonic processes power the phosphorylation of ATP Phosphorylation is not spontaneous Cellular respiration provides energy for making ATP Light energy produces ATP

  25. Catalyst - speeds up a reaction without being consumed by the reaction Enzyme = biological catalyst; protein catalyst Activation Energy (free energy of activation) - initial investment energy to start a reaction Enzymes lower activation energy thereby speeding up a reaction

  26. Exergonic or Endergonic? Why?

  27. Lowering Activation Energy: Cannot use heat because the heat required would either kill a cell or denature proteins Use a catalyst

  28. Substrate: reactant an enzyme acts on Enzyme-Substrate Complex: when enzyme binds to its substrate Active Site: where substrate binds to enzyme, usually a pocket or groove on surface of enzyme Induced Fit: brings chemical groups of active site into positions to enhance ability to catalyze reaction

  29. Substrate is held in active site by weak interactions (hydrogen bonds and ionic bonds) Side chains (R groups) of amino acids of active site of enzyme catalyze the reaction Product departs Enzyme remains UNCHANGED

  30. 1. Enzymes hold 2 or more substrates in place to catalyze a reaction 2. Active site can stretch substrates to help achieve transition-state conformation 3. Microenvironment conducive to a particular type of reaction (acidic side chains of active site) 4. Direct participation of active site in chemical reaction Brief covalent bonds

  31. Enzymes and substrates can only work so fast. Once all the active sites are occupied, a reaction cannot proceed any faster despite an increase in concentration of either enzyme or substrate

  32. Enzyme activity usually increase with temperature Too high a temperature can denature an enzyme There is an optimum temperature

  33. pH can speed up a reaction too, and also denature a protein there is an optimum pH

  34. Co-factors: nonprotein helpers 1. bound tightly to enzyme permanently 2. bind loosely and reversibly along with substrate Ex: zinc, iron and copper Coenzyme: if a cofactor is an organic molecule Ex: vitamins

  35. Competitive Inhibitors: reduce productivity of enzymes by blocking substrates from entering active sites Non-competitive Inhibitors: do not directly compete with the substrate; instead they bind to another part of the enzyme Causes enzyme to change shape making active site less effective

  36. Sarin, a nerve gas, bonds to serine (amino acid) in acetylcholinesterase of nervous system Pesticides Antibiotics Penicillin blocks active site of enzyme that bacteria use to make their cell walls

  37. Allosteric Regulation: Describe any case in which a protein's function at one site is affected by binding of a regulatory molecule to a separate site Activator: stabilizes conformation that has functional active sites Inhibitor: stabilizes the inactive form of the enzyme

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