Transcript Slide 1
• All the chemical reactions in our bodies are called metabolism. •Breakdown and reassemble molecules in the body. • Chemical bonds are broken and formed during chemical reactions. REACTANTS YIELDS CH4 + 2O2 (methane) + (oxygen) PRODUCTS CO2 + 2H2O (carbon dioxide) + (water) • Coefficients = # of molecules of a compound Ex: 6O2 = 6 molecules of Oxygen (O) 3H2O = 3 molecules of H2O CH4 + 2O2 CO2 + 2H2O • Subscripts = # of atoms of an element Ex: CH4 = 1 atom C, 4 atoms H CO2 = 1 atom of C, 2 atoms O CH4 + 2O2 CO2 + 2H2O • How many atoms of O are in 6O2 ? 12 atoms of O! • In ALL chemical equations the same number of atoms of elements are on the reactant and the product side of chemical equations o Why? Because of the Law of Conservation of Matter (atoms are never created or destroyed; they are simply rearranged!) oWe balance equations so the Law of Conservation of Mater is NOT violated! oWe must always balance equations using coefficients!! oSubscripts can never be changed! oCoefficients must always be placed in FRONT of the entire compound! oCreate an atom inventory H2 + O2 H2O CaO + KBr K2O + CaBr2 Al2S3 + BaCl2 AlCl3 + BaS • The key to a chemical reaction is energy! • Most compounds in living things cannot undergo chemical reactions without energy • Activation energy = the minimum amount of energy needed for reactants to form products in a chemical reaction o Look at Graph A: the peak in the graph represents the amount of energy that must be added to the system to make the reaction occur! Graph A • All living things are chemical factories driven by chemical reactions! • Enzymes (catalysts) need to be present in order to reduce the activation energy and allow the reaction to proceed quickly. • Look at Graph B: the enzyme lowers the activation energy and the product will be formed sooner! Graph B • Catalyst = a substance that lowers the activation energy needed to start a chemical reaction. • Enzyme = special proteins that are biological catalysts that speed up the rate of a chemical reaction Essential to life! Specific to one reaction How do ENZYMES Work? • The reactants that bind to the enzyme are called substrates. • The specific location where a substrate binds on an enzyme is called the active site. How do ENZYMES Work? • The active site and substrate have complementary shapes (lock-andkey). oEnzymes are very specific for the substrates that will change! How do ENZYMES Work? • When the enzyme-substrate complex forms, chemical bonds are broken and new bonds form to produce the products. • Enzyme releases the product and the enzyme can be used again Factors That Affect Enzymes: 1) pH (how acidic or basic a substance is) 2) Temperature • most enzymes in human cells are most active at 98.6F Examples Of Enzymes Working: • Helps with digestion • DNA replication • Enzymes in the venom of a venomous snake break down the membranes of a person’s red blood cells Examples Of Enzymes Working: • Hard green apples ripen because of the action of enzymes • Photosynthesis and cellular respiration provide energy for the cell with the help of enzymes • pH = how acidic or basic a substance is • Acid = substance that forms H+ (hydrogen ions) in water Water HCl H+ + Cl- (pH LESS than 7) • Base = substance that forms OH(hydroxide ions) in water Water NaOH Na+ + OH(pH MORE than 7) 0 7 ACID N E U T R A L 14 BASE