Stem-cells：干细胞.ppt

Enzymesn nAll chemical reactions convert All chemical reactions convert reactantsreactants to to productsproducts.Ex.2 HCl+Mg Ex.2 HCl+Mg MgCl MgCl2 2+H+H2 2n nEnzymes are a class of Enzymes are a class of proteinprotein.n nThe job of an enzyme is to The job of an enzyme is to catalyze a reaction catalyze a reaction(help it get started)(help it get started).第一页，共十六页。第二页，共十六页。第三页，共十六页。第四页，共十六页。第五页，共十六页。第六页，共十六页。n nEnzymes lower the amount of energy needed to get the reaction going activation energy.第七页，共十六页。Examplesn nDNA polymerase makes DNADNA polymerase makes DNAn nRennin curdles milk proteinRennin curdles milk proteinn nLipase breaks down fatsLipase breaks down fatsn nProtease breaks down proteinsProtease breaks down proteinsn nUsually end with“Usually end with“-ase-ase”第八页，共十六页。How do enzymes work?n nThe material that an enzyme works on is called a The material that an enzyme works on is called a substrate.substrate.n nEnzymes work like a Enzymes work like a lock and keylock and key must have must have right enzyme for each substrate.right enzyme for each substrate.第九页，共十六页。How do enzymes work?n nThe The active site active site on the enzyme is what binds to on the enzyme is what binds to the substrate.the substrate.Why enzymes?Why enzymes?Specificness and Reusing enzymesSpecificness and Reusing enzymes第十页，共十六页。Enzyme Shapen nThe shape of each protein is determined by the The shape of each protein is determined by the sequence sequence of of amino acids amino acids used to make that protein.used to make that protein.n nJust as for proteins,shape is Just as for proteins,shape is extremely importantextremely important.n nIf proteins/enzymes dont have the correct If proteins/enzymes dont have the correct temperaturetemperature,pHpH,or,or salt concentrationsalt concentration,they will lose,they will lose their shape or their shape or denaturedenature and not be able to function.and not be able to function.DenaturingDenaturing第十一页，共十六页。第十二页，共十六页。第十三页，共十六页。Tutorial activity第十四页，共十六页。Competitive Inhibitionn nIn a process called competitive inhibition,molecules that fit the active site can prevent the enzyme from working.第十五页，共十六页。内容(nirng)总结Enzymes。Usually end with“-ase”。http:/www.lewport.wnyric.org/jwanamaker/animations/Enzyme%20activity.html。Competitive Inhibition第十六页，共十六页。