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

It’s all in the cell

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

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

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.

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

Catalytic Cycle of Enzymes

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

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