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
1/12/2016 Enzymes Inhibitors: Feedback Inhibition Competitive and Noncompetitive An effective way to control bacterial growth is to inactivate enzymes, Non-competitive inhibitors Competitive inhibitors fill the active site and compete play a role in a type of with substrate.does not undergo any reaction,and is biochemical control called similar chemically to the substrate. feedback inhibition or end- 的 product inhibition The mechanism stops the cell from making more of a substance that it needs and wasting chemical resources End-predvet Feedback Inhibition Prior to 1982,only proteins were believed to have Ribozymes Anabolic pathway-final enzymatic activity end-product inhibits the Ribozyme,an enzyme activity of the first consisting of RNA,that Cea3gts附 functions as a catalyst,has enzyme in the biochemical an active site that binds pathway substrate,and is not used Entire pathway shuts down up in a reaction, and no new end-product is made sections 8e the .When the end-product is pieces together again used up,it no longer binds the first enzyme and the y of pathway resumes activity substrates compared to protein enzymes. 6
1/12/2016 6 Enzymes Inhibitors: Competitive and Noncompetitive An effective way to control bacterial growth is to inactivate enzymes. Competitive inhibitors fill the active site and compete with b t t d t d ti d i ith substrate, does not undergo any reaction, and is similar chemically to the substrate. Non-competitive inhibitors bind at a site other than the active site and alters the structure of the enzyme so that the substrate cannot bind. Feedback Inhibition • Non-competitive inhibitors play a role in a type of biochemical control called feedback inhibition or endproduct inhibition • The mechanism stops the cell from making more of a substance that it needs and wasting chemical resources Feedback Inhibition • Anabolic pathway – final end-product inhibits the activit y of the first enzyme in the biochemical pathway • Entire pathway shuts down and no new end-product is made • When the end-product is used up, it no longer binds the first enzyme and the pathway resumes activity Ribozymes • Prior to 1982, only proteins were believed to have enzymatic activity • Ribozyme, an enzyme consisting of RNA, that functions as a catalyst has functions as a catalyst, has an active site that binds substrate, and is not used up in a reaction. • Ribozyme acts on strands of RNA by removing sections and splicing the pieces together again • Ribozymes are more restricted in diversity of substrates compared to protein enzymes
1/12/2016 Energy Production Nutrient molecules,like all molecules,have energy Learning Objectives Various reactions in catabolic pathways concentrate the energy into bonds of ATP,which serves as a carrier of energy Explain the term oxidation-reduction ATP energy can be released easily and quickly due List and provide examples of 3 type of to unstable bonds phosphorylation reactions that generate ·ATP provides energy ATP for anabolic reactions Explain the overall function of metabolic pathways Oxidation-Reduction Reactions Basic ove Energy and human life Oxidation is the removal of electrons:a reaction that often produces energy Reduction is the gain of electrons Chemical waste Carbon dioxide Oxidation and reduction are always coupled Che nical energy -Water Pairing of these reactions is called oxidation reduction or a redox reaction ats ATP Heat Cells use redox reactions in catabolism to extract -Others energy from nutrients Reduction 0 Heat etabolism 08
1/12/2016 7 Learning Objectives Energy Production g j • Explain the term oxidation-reduction • List and provide examples of 3 type of phosphorylation reactions that generate ATP • Explain the overall function of metabolic pathways • Nutrient molecules, like all molecules, have energy associated with the electrons that form bonds between their atoms • Various reactions in catabolic pathways concentrate concentrate the energy into bonds of ATP, which serves as a carrier of energy • ATP energy can be released easily and quickly due to unstable bonds • ATP provides energy for anabolic reactions • Oxidation is the removal of electrons; a reaction that often produces energy • Reduction is the gain of electrons Oxidation-Reduction Reactions • Oxidation and reduction are always coupled • Pairing of these reactions is called oxidationreduction or a redox reaction • Cells use redox reactions in catabolism to extract energy from nutrients
1/12/2016 In biological systems,the electrons are An organic molecule is oxidized by the loss of two hydrogen atoms and NAD+is reduced associated with hydrogen atoms. .NAD+assists enzymes by accepting hydrogen ions Biological oxidations are often from the substrate dehydrogenations due to the loss of NADH is used to generate ATP in later reactions hydrogen ion Glucose contains many hydrogen atoms,are highly reduced,contains a large amoun t of potential energy,and is a valuable nutrient. Generation of ATP Generation of ATP Energy released during ADP oxidation-reduction Organisms use 3 mechanisms of phosphorylation reactions is trapped within Adenosine-一多-e-e to generate ATP from ADP the cell in the form of ATP Specifically,an inorganic ATP 1-substrate level phosphorylation phosphate group is added to 2-oxidative phosphorylation ADP with the input of 3-photophosphorylation energy or phosphorylation When the third phosphate is removed (dephosphorylation)energy 90g is released. 8
1/12/2016 8 • In biological systems, the electrons are associated with hydrogen atoms. • Biological oxidations are often dehydrogenations due to the loss of hydrogen ion • An organic molecule is oxidized by the loss of two hydrogen atoms and NAD+ is reduced. • NAD+ assists enzymes by accepting hydrogen ions from the substrate • NADH is used to generate ATP in later reactions NADH is used to generate ATP in later reactions. • Glucose contains many hydrogen atoms, are highly reduced, contains a large amount of potential energy, and is a valuable nutrient. Generation of ATP • Energy released during oxidation-reduction reactions is trapped within the cell in the form of ATP • Specifically, an inorganic phosphate group is added to ADP with the input of energy or phosphorylation • When the third phosphate is removed (dephosphorylation) energy is released. Generation of ATP Organisms use 3 mechanisms of phosphorylation to generate A to generate A P from ADP TP from ADP 1 – substrate level phosphorylation 2 – oxidative phosphorylation 3 - photophosphorylation
1/12/2016 Three Mechanisms of Phosphorylation to Generate ATP fef6asoa别eu将oon electron carrier,which then passes the electrons to a 5os君9on direct transfer Transfer of electrons is called an electron transport chain energy phosphate group from BLECTRON TRANSPORT CHAIN ET occurs in the one compound (substrate)to ADP 1,3-diphosphoglyceric acid+ADP e of hphogyceric C-C-C-@+ADP-C-C-C+ATP 口· ATP synthase produces ATPvia process called chemiosmosis Photophosphorylation-uses light energy to Metabolic Pathways of Energy Production phosphorylate ADP to ATP Organisms release and store energy from organic molecules Occurs in photosynthetic rof contolledrectinher hg cells. Light causes chlorophyll damage the cell. to give up electrons. To extract energy from organic compounds and store it in Energy released from chemical form,organisms pass electrons from one the transfer of compound to another via a series of oxidation-reduction reactions. electrons (oxidation) of chlorophyll through a system of carrier reactions occurring in a molecules is used to cell is called a metabolic ADP+ATP generate ATP. pathway
1/12/2016 9 Substrate level phosphorylation direct transfer of a high Three Mechanisms of Phosphorylation to Generate ATP - energy phosphate group from one compound (substrate) to ADP 1,3-diphosphoglyceric acid + ADP ATP + 3-ph hl osp oglyceric acid Oxidative phosphorylation - energy released from the transfer of electrons (oxidation) of one compound to an electron carrier, which then passes the electrons to a series of electron carriers (reduction) to molecules of oxygen or other oxidized molecules. Transfer of electrons is called an electron transport chain ET occurs in the plasma membrane of prokaryotes and the mitochondrial inner membrane of eukaryotes. ATP synthase produces ATP via a process called chemiosmosis Occurs in photosynthetic cells. Photophosphorylation - uses light energy to phosphorylate ADP to ATP Light causes chlorophyll to give up electrons. Energy released from the transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP. Metabolic Pathways of Energy Production Organisms release and store energy from organic molecules by a series of controlled reactions rather than a single burst. If the energy were released as If the energy were released as a single burst as heat a single burst as heat it , could not be used to drive chemical reactions and it would damage the cell. To extract energy from organic compounds and store it in chemical form, organisms pass electrons from one compound to another via a series of oxidation-reduction reactions. A sequence of enzymatically catalyzed chemical reactions occurring in a cell is called a metabolic pathway
1/12/2016 Carbohydrate Catabolism Catabolism:getting materials and energy Learning Objectives Glucose-most common carbohydrate energy Describe the chemical reactions of glycolysis source used by cells. Identify the functions of the pentose Most common pathway to break down glucose phosphate and Entner-Doudoroff pathways is glycolysis Explain the products of the Krebs cycle Carbohydrate metabolism is the breakdown Describe the chemiosmotic model for ATP of carbohydrate molecules to produce generation energy. Compare and contrast aerobic and anaerobic ·Three major pathways respiration 1.Aerobic respiration Describe the chemical reactions of,and list 2.Angerobic respiration some products of,fermentation 3.Fermentation Respiration:series of reactions that convert glucose to CO2 and allows the cell to recover significant amounts of energy Fermentation:when facultative and aerotolerant anaerobes use only the glycolysis scheme to incompletely oxidize glucose Aerobic respiration:When oxygen is used as the final electron acceptor at the end of the respiration scheme to produce H2O. Anaerobic respiration:Does not use molecular oxygen as the final electron acceptor,but uses nitrogen or compounds of nitrogen or sulfur or compounds of sulfur,or other inorganic substances as the final electron acceptor. 10
1/12/2016 10 Learning Objectives • Describe the chemical reactions of glycolysis Id tif th f ti f th t Carbohydrate Catabolism • Identif y th e functions of th e pentose phosphate and Entner-Doudoroff pathways • Explain the products of the Krebs cycle • Describe the chemiosmotic model for ATP generation • Compare and contrast aerobic and anaerobic respiration • Describe the chemical reactions of, and list some products of, fermentation • Glucose - most common carbohydrate energy source used by cells. M st th t b k d l s Catabolism: getting materials and energy • M ost common pathway t o break down glucose is glycolysis • Carbohydrate metabolism is the breakdown of carbohydrate molecules to produce energy. • Three major pathways 1. Aerobic respiration 2. Anaerobic respiration 3. Fermentation Respiration: series of reactions that convert glucose to CO2 and allows the cell to recover significant amounts of energy Fermentation: when facultative and aerotolerant anaerobes use only the glycolysis scheme to incompletely oxidize glucose Aerobic respiration: When oxygen is used as the final electron acceptor at the end of the respiration scheme to produce H2O. Anaerobic respiration: Does not use molecular oxygen as the final electron acceptor, but uses nitrogen or compounds of nitrogen or sulfur or compounds of sulfur, or other inorganic substances as the final electron acceptor
