Metabolism

1. Metabolism • The totality of an organism’s chemical processes, involving thousands of precisely coordinated, complex, efficient and integrated chemical reactions in the cell.

2. It’s all in the cell

3. Teaching about cell structure and function • Some different approaches • Chunking the information • Cells Alive! site

4. Enzymes = “biological catalysts” • Catalyst = chem agent that accelerates a reaction without being permanently changed • Protein • Specific • Reusable

5. Activation Energy • For reaction to occur, reactants must absorb energy to break bonds • Activation Energy is the amount of energy reactant molecules must absorb to start a chemical reaction.

6. Enzymes Lower Activation Energy • Stress bonds for catabolism (breakdown) • Orient molecules for anabolism (building) • Provide microenv. that facilitates the reaction

7. Catalytic Cycle of Enzymes

8. Factors Affecting Enzyme Activity • Temperature—increase temp, increase reaction rate, until heat denatures protein • pH – most optimal from 6-8 • Ionic conc. – most enz cannot tolerate high salinity • Many adaptations are exceptions to above

9. Enzyme Inhibitors • Some chemicals selectively prevent or reduce enzyme activity • They resemble an enzyme’s normal substrate and compete for the active site • Example: function of DDT & some Ab’s