1/12/2016 Microbes Catabolic and Anabolic Reactions Learning Objectives Invisible Invaders Amazing Allies Define metabolism and describe the fundamental differences between anabolism and catabolism UNKE Identify the role of ATP as an ASE intermediate between catabolism and Chapter 5 anabolism Microbial Metabolism Metabolism-all Two types of chemical reactions: chemical reactions and physical workings of a anabolism cell forms larger macromolecules from Metabolism is an smaller molecules: energy-balancing act requires energy input: since chemical dehydration synthesis reactions either 潭 (reactions release water) release or require energy larger mol smaller molecules: releases eneray: nydrolyfic reactions (water is used to break hydrogen bonds)
1/12/2016 1 Invisible Invaders Amazing Allies Chapter 5 Microbial Metabolism Learnin g Objectives Catabolic and Anabolic Reactions g j • Define metabolism and describe the fundamental differences between anabolism and catabolism • Identify the role of ATP as an intermediate between catabolism and anabolism Metabolism – all chemical reactions and physical workings of a cell M t b li i M eta b olism is an energy-balancing act since chemical reactions either release or require energy Two types of chemical reactions: anabolism – biosynthesis; process that forms larger macromolecules from smaller molecules; requires energy input; dehydration synthesis (reactions release water) catabolism – degradative; breaks the bonds of l l l f i larger molecules forming smaller molecules; releases energy; hydrolytic reactions (water is used to break hydrogen bonds)
1/12/2016 Role of ATP in Coupling Anabolic and Enzymes Catabolic Reactions Learning Objectives e ne Identify the components of an enzyme anabolic raions Describe the mechanism of enzymatic action .List the factors that influence enzymatic (ATP) activity possible as it stores ene Distinguish competitive and noncompetitive ism and to inhibition perform other cellular Define ribozyme work. Metabolic pathways are All of the cell's metabolic pathways are determined by determined by enzymes its enzymes.which in turn are determined by the cell's which are encoded by genetic makeup. genes. Collision Theory Collision Theory Collision theory:all atoms,ions,and Reaction rate is the frequency of collisions molecules are continuously moving and with enough energy to bring about a reaction colliding with one another.The energy Rate may be increased by increasing the transferred by the particles in the collision temperature pressure,or concentration of disrupt their electron structure to break or reactants form chemical bonds. In living organisms,enzymes increase the Activation energy is the amount of energy needed to disrupt electronic configurations reaction rate without raising the of any specific molecule:collision enerqy temperature required for a chemical reaction
1/12/2016 2 Role of ATP in Coupling Anabolic and Catabolic Reactions • Catabolic reactions provide building blocks for anabolic reactions and furnish the energy needed to drive anabolic reactions • Adenosine triphosphate (ATP) makes this coupling possible as it stores energy and releases it later to drive anabolism and to perform other cellular work. • Metabolic pathways are determined by enzymes, which are encoded by genes. Learning Objectives • Identify the components of an enzyme Enzymes • Describe the mechanism of enzymatic action • List the factors that influence enzymatic activity • Distinguish competitive and noncompetitive inhibition • Define ribozyme All of the cell’s metabolic pathways are determined by its enzymes, which in turn are determined by the cell’s genetic makeup. Collision Theory Collision theory: all atoms, ions, and molecules are continuously moving and colliding with one another. The energy transferred by the particles in the collision disrupt their electron structure to break or form chemical bonds. A ti ti n n A ctivati on e nergy is th m nt f n is th e a mount of e nergy needed to disrupt electronic configurations of any specific molecule; collision energy required for a chemical reaction Collision Theory Reaction rate is the frequency of collisions with enough energy to bring about a reaction. Rate may be increased by increasing the temperature, pressure, or concentration of reactants In living organisms, enz ymes increase the reaction rate without raising the temperature
1/12/2016 Enzymes and Chemical Reactions Enzyme-Substrate Complex enables More Effective Enzymes are biological catalysts that increase the Collisions Lowering the Activation Energy 0 activation without increasing the living cell. Catalyst:a substance that speeds up a chemical reaction without being permanently altered in the complex reaction. Enzyme promotes a reaction hy serving 1.Subsecontacts the active siteon enzyme as a physical site 2.Forms an enzyme-substrate complex for specific 3.Substrate is transformed into products substrate molecules to position. 4.Products are released 5.Enzyme is recovered unchanged Enzyme Specificity and Efficiency Hexokinase The three-dimensional structure of an enzyme determines its substrate specificity Unique structure enables each enzyme to find its Substrate B Substrate C substrate among diverse 巴世 molecules in the cell. Enzymes are very efficient
1/12/2016 3 Enzymes and Chemical Reactions Enzymes are biological catalysts that increase the rate of a chemical reaction by lowering the energy of activation without increasing the temperature of the living cell. Catalyst: a substance that speeds up a chemical reaction without being permanently altered in the reaction. Enzyme promotes a r act n y r ng eaction by serving as a physical site for specific substrate molecules to position. Enzyme-Substrate Complex enables More Effective Collisions Lowering the Activation Energy 1. Substrate contacts the active site on the enzyme 2. Forms an enzyme-substrate complex 3. Substrate is transformed into products 4. Products are released 5. Enzyme is recovered unchanged Hexokinase Enzyme Specificity and Efficiency • The three-dimensional structure of an enzyme determines its substrate specificity • Unique structure enables each enzyme to find its substrate among diverse molecules in the cell. • Enzymes are very efficient
1/12/2016 Enzyme Specificity and Efficiency Enzyme Components Some enzymes are entirely protein Under optimum conditions,they can ·Most consist of catalyze a reaction up to -a protein part 10 billion times faster apoenzyme than without an enzyme -a non-protein part The turnover number of cofactor substrate molecules is Apoenzymes are inactive generally 1-10,000 without the cofactor molecules per second! Cofactors examples:ions Mechanism of of iron,zinc,magnesium or Enzyme Components Enzymatic Action calcium:form a bridge between enz Coenzyme is a cofactor that is organic in nature and assists the enzyme by donating atoms required for the substrate Products no longer fit Coenzyme examples: vitamins,NAD,NADP icotinar ide adenine dinucleotide(phosphate)
1/12/2016 4 Enzyme Specificity and Efficiency • Under optimum conditions they can conditions, they can catalyze a reaction up to 10 billion times faster than without an enzyme • The turnover number of subst t m l cul s is substrate molecules is generally 1-10,000 molecules per second! Enzyme Components • Some enzymes are entirely protein • Most consist of - a protein part apoenzyme - a non-protein part cofactor • Apoenzymes are inactive without the cofactor • Holoenzyme – apoenzyme plus the cofactor • Cofactors examples: ions Enzyme Components of iron, zinc, magnesium or calcium; form a bridge between enzyme and substrate, trace elements • Coenzyme is a cofactor that is organic in nature and assists the enzyme by accepting atoms removed from the substrate or donating atoms required for the substrate • Coenzyme examples: vitamins, NAD, NADP, nicotinamide adenine dinucleotide (phosphate) Mechanism of Enzymatic Action Enzyme: Sucrase Products no longer fit
1/12/2016 Factors Influencing Enzyme Activity Factors Influencing Enzymatic Activity ·Temperature ·pH Substrate concentration ·Inhibitors 综的 Active(rotein Denatued proin Enzymes can be denatured by temperature and pH 3D-structure is lost Factors Influencing Enzymatic Activity Substrate concentration nfluences enzyme activity Factors Influencing a)Enzyme activity Enzymatic Activity increases with .Enzymes have a maximum rate at which they can catalyze a increasing specific reaction.This occurs temperature until the when the concentration of enzyme,a protein,is substrate is high, denatured by heat and saturation At a high level,the enzyme inactivated b)Hydrogen ions compete Steaoloysocpedond with hydrogen and A further increase in ionic bonds in an centration at this point will not increase the enzyme activity enzyme and denature the 3D structure.The 24 Under normal cellular activity, enzyme illustrated is enzymes are not saturated and substrate levels inf luence Substrate concentration most active at pH 5.0 enzyme activity
1/12/2016 5 Factors Influencing Enzyme Activity • Temperature • pH • Substrate concentration • Inhibitors Factors Influencing Enzymatic Activity Enzymes can be denatured by temperature and pH 3D-structure is lost Factors Influencing Enzymatic Activity a) Enzyme activity increases with increasing temperature until the enzyme, a protein, is denatured by heat and inactivated b) Hydrogen ions compete with hy g dro en and ionic bonds in an enzyme and denature the 3D structure. The enzyme illustrated is most active at pH 5.0 Factors Influencing Enzymatic Activity Substrate concentration influences enzyme activity • Enzymes have a maximum rate at which they can catalyze a specific reaction. This occurs when the concentration of substrate is high. • At a high level, the enzyme active site is always occupied and is saturated. • A further increase in n nt ti n t this p int ill saturation concentration at this point will not increase the enzyme activity. • Under normal cellular activity, enzymes are not saturated and substrate levels influence enzyme activity