1. BIOLOGY MS. POLLOCK 2013 - 2014 2.2 Biochemical Reactions

2. What Are Chemical Reactions? Process that changes some chemical substances to others Reactant – substance that starts chemical reaction Product – substance that forms as result of chemical reaction Example: burning of methane CH 4 + 2 O 2  CO 2 + 2 H 2 O Reactants: CH 4 and O 2 Products: CO 2 and H 2 O

3. Chemical Equations Represent chemical reactions Arrow to show direction of reaction and separate reactants from products Coefficients to show number of each type of substance in reaction

4. Conservation of Matter Quantity of elements unchanged in chemical reaction Same amount of each element in products as in reactants

5. Chemical Reactions and Energy Energy always involved in chemical reactions Exothermic reactions – release energy as heat  Reactants  Products + Heat Endothermic reactions – absorb energy  Reactants + Heat  Products

6. Activation Energy Energy needed to start all reactions Activation energy – energy needed to start reaction Reactant molecules moving to begin reactions

7. Biochemical Reactions and Enzymes Biochemical reactions – chemical reactions that take place in the cells of living things Chemistry necessary for understanding life processes of organisms at cell level Metabolism – sum of all biochemical reactions in an organism; both endothermic and exothermic reactions

8. Types of Biochemical Reactions Catabolic reactions – exothermic reactions in organisms  Break down molecules into smaller units and release energy  Breakdown of glucose to energy for life processes Anabolic reactions – endothermic reactions in organisms  Build up bigger molecules from smaller ones  Amino acids combined to form protein

9. Types of Biochemical Reactions

10. Enzymes Most biochemical reactions need help to start Temperatures possibly too low Concentrations of reactants possibly too low Help from enzymes

11. Enzymes Enzyme – protein that speeds up biochemical reaction Reduces amount of activation energy needed to start reaction Less activation energy needed to start reaction when correct enzyme present Reactions that normally take days to occur can happen in a fraction of a second. With enzymes, many organisms unable to survive Activity dependent on temperature, ionic conditions, and pH

12. Enzymes