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

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Presentation on theme: "ENERGY, THERMODYNAMICS and ENZYMES © 2012 Pearson Education, Inc."— Presentation transcript:

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: 1.Kinetic energy is the energy of motion. 2.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 Fuel Energy conversion Waste products Gasoline Oxygen Glucose Heat energy Combustion Kinetic energy of movement Energy conversion in a car Energy conversion in a cell Energy for cellular work Cellular respiration ATP Heat energy Carbon dioxide Water

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 organisms 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 Energy Products Amount of energy released Potential energy of molecules

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

10 Cells need energy to perform work!! There are three main types of cellular work: 1.chemical 2.mechanical 3.transport ATP drives all three of these types of work. © 2012 Pearson Education, Inc.

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

12 Figure 5.12A_s2 ADP: Adenosine Diphosphate P P P Energy H2OH2O Hydrolysis Ribose Adenine P P P Phosphate group ATP:Adenosine Triphosphate

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 ATP ADP P P P P P P P P P Chemical work Mechanical workTransport work Reactants Motor protein Solute Membrane protein Product Molecule formed Protein filament moved Solute transported

15 How Does Cell Regenerate ATP? © 2012 Pearson Education, Inc. Energy from exergonic reactions Energy for endergonic reactions ATP ADP P 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.

16 HOW ENZYMES FUNCTION © 2012 Pearson Education, Inc.

17 Enzymes = Organic catalysts Increase RATE of chemical reaction by decreasing activation energy (E A ). –E A = energy barrier must be overcome before any chemical reaction can begin. © 2012 Pearson Education, Inc. Activation energy barrier Reactant Products Without enzyme With enzyme Reactant Products Enzyme Activation energy barrier reduced by enzyme Energy Animation: How Enzymes Work

18 Reactants Products Energy Progress of the reaction a b c 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 Products are released Fructose Glucose Enzyme (sucrase) Active site Enzyme available with empty active site Substrate (sucrose) Substrate binds to enzyme with induced fit Substrate is converted to products H2OH2O Catalytic cycle of an enzyme

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 enzymes activity. © 2012 Pearson Education, Inc. Substrate Enzyme Allosteric site Active site Normal binding of substrate Competitive inhibitor Noncompetitive inhibitor Enzyme inhibition Competitive inhibitors –block substrates from entering the active site and –reduce an enzymes 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.

28 Feedback inhibition Starting molecule Product Enzyme 1 Enzyme 2 Enzyme 3 Reaction 1 Reaction 2 Reaction 3 A B C D 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

29 1.Describe the fluid mosaic structure of cell membranes. 2.Describe the diverse functions of membrane proteins. 3.Relate the structure of phospholipid molecules to the structure and properties of cell membranes. 4.Define diffusion and describe the process of passive transport. You should now be able to © 2012 Pearson Education, Inc.

30 5.Explain how osmosis can be defined as the diffusion of water across a membrane. 6.Distinguish between hypertonic, hypotonic, and isotonic solutions. 7.Explain how transport proteins facilitate diffusion. 8.Distinguish between exocytosis, endocytosis, phagocytosis, pinocytosis, and receptor-mediated endocytosis. You should now be able to © 2012 Pearson Education, Inc.

31 9.Define and compare kinetic energy, potential energy, chemical energy, and heat. 10.Define the two laws of thermodynamics and explain how they relate to biological systems. 11.Define and compare endergonic and exergonic reactions. 12.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 13.Explain how ATP functions as an energy shuttle. 14.Explain how enzymes speed up chemical reactions. 15.Explain how competitive and noncompetitive inhibitors alter an enzymes activity. 16.Explain how certain drugs, pesticides, and poisons can affect enzymes. © 2012 Pearson Education, Inc.

33 Table 5.UN05

34 Figure 5.UN06 pH Rate of reaction

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