Transcript Metabolism
Metabolism Basic Concepts and Design Metabolism What is metabolism? all the chemical reactions that take place in cells series of energy transformations Why do living organism require energy? to synthesize large molecules from small ones to move substances in and out of cells muscle contraction and cell movement Metabolism What is the difference between phototrophs and chemotrophs? phototrophs obtain energy from sunlight chemotrophs obtain energy from breaking chemical bonds What is the difference between anabolic and catabolic reactions? catabolic – fuels degraded to release useful energy anabolic – energy used to synthesize biomolecules Metabolism Why are reactions often coupled in metabolic pathways? to insure that the overall free energy change is negative a reaction that requires energy may be paired with one that releases energy Glucose 2ADP + 2Pi 2Lactate G°' = -184.5 kJ mol -1 2ATP + 2 H2 O G°' = +61.0 kJ mol -1 Glucose + 2ADP + 2Pi 2Lactate + 2ATP + 2 H2 O G°' = -123.5 kJ mol -1 Metabolism What is the role of ATP in cells? donor of free energy in energy requiring reactions Why is ATP an energy rich molecule? Metabolism What are the factors that contribute to the large amount of energy released when ATP is hydrolzed? resonance stabilization electrostatic repulsion ease of hydration Metabolism Metabolism What do we mean by phosphoryl transfer potential? ability to donate a phosphate group What molecules besides ATP can transfer PO4 groups? Metabolism How is ATP regenerated in cells? Metabolism The oxidation of which of these two molecules will produce more ATP and why? Metabolism • How do molecules with high phosphoryl transfer potential couple the oxidation of carbon to the synthesis of ATP? glyceraldehyde-3-PO4 + NAD+ + HPO4 1,3 biphosphoglycerate + NADH + H+ 1,3 biphosphoglycerate + ADP 3phosphoglyceric acid + ATP Metabolism Metabolism What is happening at each stage of catabolism? Metabolism While ATP is an activated carrier of phosphoryl groups, what molecule(s) is (are) activated carrier(s) of electrons during oxidation? nicotinamine adenine dinucleotide (NAD) flavin adenine dinucleotide (FAD) Metabolism Metabolism O CNH2 N+ Ad + H+ + 2 e - NAD + (oxidized form) H O CNH2 H N Ad NADH (reduced form) Metabolism One H is transferred to NAD with 2 electrons and the other H goes into solution as a proton. Metabolism Metabolism Metabolism What activated carrier for electrons is used in most biosynthetic reactions or the reaction shown above? NADPH Metabolism Why is coenzyme A an important molecule in metabolism? carrier of acyl groups Metabolism Metabolism While metabolism consists of thousands of reactions, each reaction falls into one of six categories. Oxidation-Reduction Reaction Ligation Reaction Isomerization Reaction Group Transfer Reaction Hydrolytic reaction Addition or Removal of Functional Groups Regulation of Metabolism What are the three basic ways in which metabolic reactions are regulated? controlling amount of enzyme influencing rate of transcription altering catalytic activity allosterically covalent modification controlling accessibility of substrates Regulation of Metabolism How do hormones influence metabolism? alteration of enzyme activity glucagon and glycogen phosphorylase What other factors influence metabolism? compartmentalization energy status of cell Metabolism What do ATP, NADH, FAD and coenzyme A have in common and what does this indicate about these molecules? adenosine diphosphate evolved from early RNA catalysts