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6.2 CHEMICAL REACTIONS WHAT YOU WILL LEARN -the parts of a chemical reaction -how energy changes relate to chemical reactions -the importance of enzymes in organisms MAIN IDEA: Chemical reactions allow living things to grow, develop, reproduce, and adapt REACTANTS/PRODUCTS CHEMICAL REACTION--process in which atoms are reorganized to make new substances: CH4 + 2O2 REACTANTS -subscript: # of atoms -coefficient: # of molecules -: direction of reaction → CO2 + 2H2O → PRODUCTS EXPLAIN: What is the relationship between a chemical bond and a chemical reaction? -chemical BONDS created/broken by chemical REACTIONS REACTANTS/PRODUCTS CONSERVATION of MASS MATTER cannot be created or destroyed created or __________ destroyed -atoms are NOT __________ # atoms in REACTANTS = # atoms in PRODUCTS VIDEO CLIP BALANCE EQUATIONS 1- DETERMINE # atoms for each element –track w/tallies 2- PICK an element that is NOT equal on both sides of the equation 3- ADJUST your # atoms on each side of equation so both are equal 4- USE coefficients to show the # of atoms of each element on each side ____Mg + ____HCl ____MgCl2 + ____ H2 Mg= Mg= H= H= Cl= Cl= ____H2O2 ____H2O + ____O2 H= H= O= O= ENERGY of REACTIONS ENDOTHERMIC REACTIONS: -absorbs energyCOLD -need MORE energy to form new bonds in products Ex: photosynthesis EXOTHERMIC REACTIONS: -releases energyHOT -need MORE energy to break bonds in reactants Ex: sodium + chlorine table salt ENZYMES activation energy: -least amount energy needed to start a reaction --------------------------------------------------------------------------CATALYST LOWERS -substances that __________activation energy needed speeds up -anything that ________________ a chemical reaction ----------------------------------------------------------------------------- ENZYMES Enzyme ANIMATION -special proteins -lower activation energy needed -biological catalysts -speeds up reactions in living things -COMPOSED OF: -protein -PURPOSE: -speeds up rate of chemical reactions in biological process -REUSABLE: -YES--not used up in reaction -ACTIVITY LEVEL AFFECTED/INFLUENCED BY: -pH, temperature, other substances NATURALLY PRESENT in FRUIT / RAW FOOD Each ENZYME usually “participates” in ONE type of reaction ENZYMES LABEL 3 parts of process with brief description substrates—REACTANT substrate binds to active site in enzyme enzyme changes shape enzyme releases product ANALOGY: PUZZLE--right pieces fit--bend puzzle to change shape--pieces will pop out ENZYMES/ BIOLOGICAL ENZYMES NAME some biological processes that require enzymatic activity-muscle contraction -cell division -digestion ENZYMES/ BIOLOGICAL ENZYMES: (EX/uses) PROTEASE -secreted in pancreas / activated in small intestine -break down proteins -amino acids needed for body AMYLASE -produced by pancreas /present in saliva -breaks down starch to sugar LIPASE -produced by the pancreas -break down fats -used in digestion REVIEW/PRACTICE 1- What principle can be applied to all chemical reactions? conservation of mass reactants formed from products coefficient principle 2- The minimum amount of energy needed for a chemical reaction is called: principle mass absorbent energy activation energy 3- What is the function of the enzyme-substrate? destroy the enzyme break and form chemical bonds stop chemical reactions 4- In which of the following are bonds broken and new bonds formed? polar molecules chemical reactions isotopes 5- Which statement is true of chemical reactions? bonds break in reactants bonds break in products products have fewer atoms than reactants REVIEW/PRACTICE 6-DESCRIBE the importance of enzymes to living organisms -speeds up biological chemical reactions 7- IDENTIFY/DESCRIBE 2 factors that can influence enzyme activity. -temp, pH, substrate concentration REVIEW/PRACTICE 10- DESCRIBE the effect temperature has on the rate of the reactions. -temp increases the rate of both reaction within specific ranges 9- INFER which enzyme is more active in a human cell Enzyme A Enzyme B EXPLAIN why-maximal activity around 37ºC 6.2 CHEMICAL REACTIONS AFTER YOU READ Explain the role of chemical reactions in living things All processes in living things are controlled by chemical reactions REACTANTS/PRODUCTS BONDS in REACTANTS molecules/compounds break ATOMS rearrange new bonds form in PRODUCTS CH4 + 2O2 → CO2 + 2H2O reactants → products subscript: # atoms in molecule coefficient: # of molecules REACTANTS/PRODUCTS CALCULATE the number of atoms of each element in the chemical equation: CH4 + 2O2 Element symbol Element name C H O carbon hydrogen oxygen → CO2 + 2H2O # atoms in REACTANT ANAYLYZE—is equation balanced? STATE principle that explains why # atoms in reactants = # atoms in products # atoms in PROCUCT ENZYMES MATCHING act energy -____________min energy required for reactants to form products catalyst -____________substance lowers energy needed to start reaction enzyme -____________protein that is biological catalyst substrate -____________molecule binds to an enzyme ENERGY of REACTIONS EXOTHERMIC REACTION ENDOTHERMIC REACTION energy is released energy is absorbed gets HOT gets COLD Energy of PRODUCT is LOWER than energy of REACTANTS DEMO Energy of PRODUCT is HIGHER than energy of REACTANTS ENERGY of REACTIONS EXOTHERMIC—release energy HOT ENDOTHERMIC—absorb energy COLD ENZYMES SUMMARIZE: Reusable? yes Composed of: proteins ENZYMES Purpose: speed up reactions Activity level affected by: temp/pH PARTICIPATES IN HOW MANY DIFFERENT TYPES OF REACTIONS? 1-Specific to each enzyme ENZYMES INTERPRET: pathway of reaction with an enzyme present ENZYMES ILLUSTRATE enzyme-substrate complex in cartoon form ENZYMES ANALYZE the role of catalysts in chemical reactions -speed up the reaction DESCRIBE the importance of enzymes in living organisms -allow all biological functions to occur