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AP Biology Chapter 8: Metabolism and Enzymes. Kinetic Energy vs. Potential Energy.

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Presentation on theme: "AP Biology Chapter 8: Metabolism and Enzymes. Kinetic Energy vs. Potential Energy."— Presentation transcript:

1 AP Biology Chapter 8: Metabolism and Enzymes

2 Kinetic Energy vs. Potential Energy

3 Potential Energy vs. Kinetic Energy


5 Thermodynamics

6 LE 8-3 Chemical energy Heat CO 2 First law of thermodynamicsSecond law of thermodynamics H2OH2O

7 LE 8-7a G = 0 A closed hydroelectric system G < 0

8 LE 8-7b An open hydroelectric system G < 0

9 LE 8-7c A multistep open hydroelectric system G < 0

10 LE 8-6a Reactants Energy Products Progress of the reaction Amount of energy released ( G < 0) Free energy Exergonic reaction: energy released

11 LE 8-6b Reactants Energy Products Progress of the reaction Amount of energy required ( G > 0) Free energy Endergonic reaction: energy required

12 Fig: 8.8

13 Phosphorylation

14 LE 8-11 NH 2 Glu P i P i P i P i NH 3 P P P ATP ADP Motor protein Mechanical work: ATP phosphorylates motor proteins Protein moved Membrane protein Solute Transport work: ATP phosphorylates transport proteins Solute transported Chemical work: ATP phosphorylates key reactants Reactants: Glutamic acid and ammonia Product (glutamine) made + + +

15 LE 8-15 Course of reaction without enzyme E A without enzyme G is unaffected by enzyme Progress of the reaction Free energy E A with enzyme is lower Course of reaction with enzyme Reactants Products

16 LE 8-16 Substrate Active site Enzyme Enzyme-substrate complex

17 LE 8-17 Enzyme-substrate complex Substrates Enzyme Products Substrates enter active site; enzyme changes shape so its active site embraces the substrates (induced fit). Substrates held in active site by weak interactions, such as hydrogen bonds and ionic bonds. Active site (and R groups of its amino acids) can lower E A and speed up a reaction by acting as a template for substrate orientation, stressing the substrates and stabilizing the transition state, providing a favorable microenvironment, participating directly in the catalytic reaction. Substrates are converted into products. Products are released. Active site is available for two new substrate molecules.

18 R groups of Amino Acids

19 Optimal Performance

20 LE 8-19 Substrate Active site Enzyme Competitive inhibitor Normal binding Competitive inhibition Noncompetitive inhibitor Noncompetitive inhibition A substrate can bind normally to the active site of an enzyme. A competitive inhibitor mimics the substrate, competing for the active site. A noncompetitive inhibitor binds to the enzyme away from the active site, altering the conformation of the enzyme so that its active site no longer functions.

21 LE 8-20a Allosteric enzyme with four subunits Regulatory site (one of four) Active form Activator Stabilized active form Active site (one of four) Allosteric activator stabilizes active form. Non- functional active site Inactive form Inhibitor Stabilized inactive form Allosteric inhibitor stabilizes inactive form. Oscillation Allosteric activators and inhibitors

22 LE 8-21 Active site available Initial substrate (threonine) Threonine in active site Enzyme 1 (threonine deaminase) Enzyme 2 Intermediate A Isoleucine used up by cell Feedback inhibition Active site of enzyme 1 cant bind theonine pathway off Isoleucine binds to allosteric site Enzyme 3 Intermediate B Enzyme 4 Intermediate C Enzyme 5 Intermediate D End product (isoleucine)

23 LE 8-20b Substrate Binding of one substrate molecule to active site of one subunit locks all subunits in active conformation. Cooperativity another type of allosteric activation Stabilized active form Inactive form

24 LE 5-20e Chains Hemoglobin Iron Heme Collagen Polypeptide chain Polypeptide chain

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