Recommended
More Related Content
What's hot
Similar to Biol101 chp8-pp-fall10-101121172632-phpapp01
Similar to Biol101 chp8-pp-fall10-101121172632-phpapp01 (20)
More from Cleophas Rwemera
More from Cleophas Rwemera (20)
Recently uploaded
Recently uploaded (20)
Biol101 chp8-pp-fall10-101121172632-phpapp01
- 1. An Introduction to Metabolism BIOL 101: General Biology I Chapter 8 Rob Swatski Associate Professor of Biology HACC – York Campus 1
- 2. Overview: The Energy of Life • The living cell is a miniature chemical factory where thousands of reactions occur • The cell extracts energy and applies energy to perform work • Some organisms even convert energy to light, as in bioluminescence
- 3. 3
- 6. 6
- 7. An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics • Metabolism is the totality of an organism’s chemical reactions • Metabolism is an emergent property of life that arises from interactions between molecules within the cell
- 10. 10
- 12. Enzyme 1 Enzyme 2 Enzyme 3 BA Reaction 1 Reaction 3Reaction 2 Starting Molecule (Substrate) Product B C D Bioenergetics: study of how organisms manage their energy resources Metabolic Pathway 12
- 13. AB A B Catabolic Pathways 13 …release energy
- 14. Light energy ECOSYSTEM Photosynthesis in chloroplasts CO2 + H2O Cellular respiration in mitochondria Organic molecules + O2 ATP powers most cellular work Heat energy ATP exergonic endergonic 14
- 15. 15
- 16. A B AB 16 Anabolic Pathways …gain energy
- 17. Light energy ECOSYSTEM Photosynthesis in chloroplasts CO2 + H2O Cellular respiration in mitochondria Organic molecules + O2 ATP powers most cellular work Heat energy ATP exergonic endergonic 17
- 18. 18
- 20. A diver has more potential energy on the platform than in the water. Diving converts potential energy to kinetic energy. Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential energy in the water than on the platform.
- 22. 22
- 23. 23
- 24. 24 First Law of Thermodynamics = Principle of Conservation of Energy The energy of the universe is constant Energy can be transferred & transformed, but… …it cannot be created or destroyed
- 25. First law of thermodynamics
- 26. 26 Total Energy of Reactants Total Energy of Products First Law of Thermodynamics
- 27. 27 Second Law of Thermodynamics During every energy transfer or transformation… …some energy is unusable & is often lost as heat Every energy transfer or transformation increases the entropy (disorder) of the universe
- 28. Heat Second Law of Thermodynamics
- 29. 29 Spontaneous Processes Occur without any energy input Can be fast or slow Must always increase the entropy of the universe
- 30. 30
- 31. 31
- 32. 32 Biological Order & Disorder Cells create order from disorder Energy flows into an ecosystem as light… …and flows out of an ecosystem as heat
- 33. Primary producers Energy flow Chemical cycling Primary consumers Secondary consumers Tertiary consumers Microorganisms and other detritivores Detritus Sun Heat 33
- 34. 34 Why doesn’t the evolution of more complex forms of life violate the Second Law?
- 35. 35 Effie Sue
- 36. 36 Entropy may decrease in an individual organism, but the total entropy of the universe is still increasing
- 37. 37
- 38. 38 Energy and Chemical Reactions Which reactions are spontaneous? Which reactions require an input of energy? How does energy change during a chemical reaction?
- 39. 39 Free Energy Energy in a living cell that can do work when temperature & pressure are uniform Change in free energy (∆G) - ∆G reactions are spontaneous & can be harnessed to do work
- 40. 40
- 41. 41 ∆G = ∆H – T∆S ∆H = the change in enthalpy (total energy) T = temperature in degrees Kelvin ∆S = the change in entropy
- 42. 42 Free Energy Free energy measures a system’s stability Unstable systems tend to become more stable - ∆G reactions: free energy decreases & stability increases Moves toward equilibrium (maximum stability)
- 43. Less free energy (lower G) More stable Less work capacity More free energy (higher G) Less stable Greater work capacity In a spontaneous change: The free energy of the system decreases (∆G < 0) The system becomes more stable The released free energy can be harnessed to do work 43
- 44. Spontaneous change Spontaneous change Spontaneous change Diffusion Chemical reactionGravitational motion 44
- 45. 45 Energy Energy Exergonic Reaction Spontaneous: releases free energy
- 46. 46 Energy EnergyEndergonic Reaction Nonspontaneous: absorbs free energy
- 47. Energy Exergonic reaction Progress of the reaction Freeenergy Products Amount of energy released (∆G < 0) Reactants 47
- 48. Energy Endergonic reaction Progress of the reaction Freeenergy Products Amount of energy required (∆G > 0) Reactants 48
- 49. 49 Closed Systems Reactions in closed systems eventually reach equilibrium and… …cannot do any more work
- 50. Closed hydroelectric system ∆G < 0 ∆G = 0 50
- 51. 51 Open Systems Life consists of open systems that do not reach equilibrium Materials are constantly flowing in and out Metabolism is never at equilibrium
- 52. ∆G < 0 Open hydroelectric system 52
- 53. ∆G < 0 ∆G < 0 ∆G < 0 Open multistep hydroelectric system 53
- 55. 55 Kinesin
- 57. 57
- 58. 58 ATP: Adenosine Triphosphate Main energy molecule of the cell Ribose (sugar) Adenine (nitrogenous base) 3 Phosphate groups
- 60. 60 ATP Hydrolysis Breaks the terminal phosphate bond of ATP Releases energy to power all cellular work ATP is now in a state of lower free energy
- 61. Inorganic phosphate Energy Adenosine triphosphate (ATP) Adenosine diphosphate (ADP) P P P P P P ++ H2O i 61
- 62. 62 Phosphorylation How ATP drives endergonic reactions Transfers a phosphate group to another molecule The recipient molecule is now phosphorylated P
- 63. (b) Coupled with ATP hydrolysis, an exergonic reaction Ammonia displaces the phosphate group, forming glutamine. (a) Endergonic reaction (c) Overall free-energy change P P Glu NH3 NH2 Glu i Glu ADP+ P ATP+ + Glu ATP phosphorylates glutamic acid, making the amino acid less stable. Glu NH3 NH2 Glu + Glutamic acid GlutamineAmmonia ∆G = +3.4 kcal/mol + 2 1 63
- 64. Mechanical work: ATP binds non-covalently to motor proteins, then is hydrolyzed P i ADP + P P i Transport work: ATP phosphorylates transport proteins ATP ATP 64
- 65. P iADP + Energy from catabolism (exergonic) Energy for cellular work (endergonic) H2OATP +ATP ATP = Renewable Resource Phosphorylation of ADP 65
- 66. 66 Enzymes Catalysts: speed up a reaction Are not consumed by the reaction Enzyme-catalyzed reaction
- 69. 69
- 70. Sucrose (C12H22O11) Glucose (C6H12O6) Fructose (C6H12O6) Sucrase Sucrose Hydrolysis by Sucrase 70
- 71. 71 Activation Energy (EA) Energy needed to start a chemical reaction Often supplied by surrounding heat Activation energy barrier
- 72. 72
- 73. Progress of the reaction Products Reactants ∆G < O Transition state EA DC BA D D C C B B A A 73
- 74. 74 Enzymes and EA Enzymes lower the EA barrier Do not affect the change in free energy (∆G) Enzymes accelerate reactions that would eventually occur
- 75. Course of reaction without enzyme EA without enzyme EA with enzyme is lower Course of reaction with enzyme Reactants Products G is unaffected by enzyme Progress of the reaction Freeenergy
- 78. 78 How Do Enzymes Lower the EA barrier? Form multiple bonds with substrates Properly orient substrate Provide a favorable microenvironment Strain substrate bonds
- 79. Substrates Enzyme Products are released Products Substrates converted into products Lower EA speeds up reaction Hydrogen bonds & ionic bonds form between enzyme & substrates Substrates enter active site Active site is open for new substrates Enzyme-substrate complex 5 3 2 1 6 4 79
- 81. Rateofreaction Optimal temperature for enzyme of thermophilic (heat-tolerant) bacteria Optimal temperature for typical human enzyme Optimal temperature for two enzymes Optimal pH for two enzymes Rateofreaction Optimal pH for pepsin (stomach enzyme) Optimal pH for trypsin (intestinal enzyme) Temperature (ºC) pH 543210 6 7 8 9 10 0 20 40 8060 100 Effects of Temperature & pH on Enzyme Activity 81
- 84. Normal binding Noncompetitive inhibitionCompetitive inhibition Noncompetitive inhibitor Active site Competitive inhibitor Substrate Enzyme 84
- 85. 85 Allosteric Regulation of Enzyme Activity May stimulate or inhibit enzyme activity Regulatory protein binds to enzyme at one site… …and affects enzyme function at another site Activators & inhibitors
- 86. Inhibitor Non- functional active site Stabilized inactive form Inactive form Oscillation Activator Active form Stabilized active formRegulatory site (1 of 4) Allosteric enzyme with 4 subunits Active site (1 of 4) Allosteric Activators & Inhibitors 86
- 87. 87 Cooperativity Another type of allosteric activation Amplifies enzyme activity Substrate binds to one active site… …and stabilizes favorable shape changes at all other active sites
- 89. 89 Identification of Allosteric Regulators Attractive drug candidates for enzyme regulation Example: inhibit proteolytic enzymes (caspases) May help manage inappropriate inflammatory responses
- 90. SH Substrate Hypothesis: allosteric inhibitor locks enzyme in inactive form Active form can bind substrate S–S SH SH Active site Caspase 1 Known active form Known inactive form Allosteric binding site Allosteric inhibitor EXPERIMENT 90
- 91. Caspase 1 RESULTS Active form Allosterically inhibited form Inactive form Inhibitor 91
- 92. 92 Feedback Inhibition End product of enzymatic pathway… …shuts down the pathway Prevents a cell from wasting resources
- 93. Active site available Isoleucine used up by cell Feedback inhibition Active site of enzyme 1 is no longer able to catalyze the conversion of threonine to intermediate A; pathway is switched off. Isoleucine binds to allosteric site. Initial substrate (threonine) Threonine in active site Enzyme 1 (threonine deaminase) Intermediate A Intermediate B Intermediate C Intermediate D Enzyme 2 Enzyme 3 Enzyme 4 Enzyme 5 End product (isoleucine)
- 94. Tonyjaase Enzyme Substrate 1 Substrate 2 Active Sites Tonyjaaase Enzyme in Action video 94
- 95. Specific Localization of Enzymes Within the Cell • Structures within the cell help bring order to metabolic pathways • Some enzymes act as structural components of membranes • In eukaryotic cells, some enzymes reside in specific organelles; for example, enzymes for cellular respiration are located in mitochondria
- 96. Mitochondria The matrix contains enzymes in solution that are involved in one stage of cellular respiration. Enzymes for another stage of cellular respiration are embedded in the inner membrane. 1 m