1、Definition The sum of all biochemical reactions that involves energy transformation.Types Catabolism:degradative pathways Three stages,Usually energy-yielding!Anabolism:biosynthetic pathways -energy-requiring!Metabolic pathway A cascade of reactions leading to the synthesis or degradation of a compo
2、und.Anabolic pathways Catabolic pathways Amphibolic pathway(无定向代谢途径无定向代谢途径）FeaturesMetabolic pathways are irreversible(because they must be regulated)Reaction conditions are mildHighly conserved among speciesMetabolic pathways have(first)committed stepMetabolic pathways are regulated Metabolic pathw
3、ays are compartmentalizedAnabolic and catabolic pathways must differ in at least one step in order to be regulatedDegradation:biomolecules building blocks common intermediates-final productsMitochondria(TCA cycle,OxPhos,fatty acid oxidation,amino acid breakdown)Cytosol(glycolysis,fatty acid biosynth
4、esis,pentose phosphate cycle)Nucleus(DNA replication,transcription,RNA processing)ER(Rough ER:synthesis of membrane and secretory proteins,smooth ER:lipid and steroid biosynthesis)Golgi(posttranslational processing of proteins)The enzymes may be separateOr may form a multienzyme complexOr may be a m
5、embrane-bound system Or may exist in a multi-funtional enzymeNew research indicates that multienzyme complexes are more common than once thought Sequence of reactionsMechanisms of each reactionRegulation of pathwaysHypotheses or exploration?Methods:Isotope tracer radioactive:14C、32P、35S、3H；Stable：18
6、O、14NInhibitors(accumulation of intermediates)Genetic defects(also accumulation of intermediates)Genetic manipulations:animals(transgenic,knockout),expression in certain tissuesEmerging methods:sequence methods(genome projects),bioinformatics,high throughput gene expression methods Cells need a cons
7、tant supply of energy NADH,NADPH and ATP ATP-energy currency NADPH-reducing power Glucose-NADH-ATP Glucose-NADPH-biosynthesis(reductive)Metabolome&MetabolomicsMetabolome&Metabolomics*The small molecule inventory(SMI)or Metabolome is a pattern of molecules that reflects the cells status.It is the tot
8、ality of metabolic processes including anabolism and catabolism,as well as all the related cellular processes such as absorption,distribution,and detoxification of natural and xenobiotic materials,energy utilization,signal transduction,and regulation.It results from the expression of the genome and
9、proteome in response to the cellular environment.While the Genome is representative of what might be,and the Proteome is what is expressed,it is the Metabolome that represents the current status of the cell or tissue.*The Metabolome gives a direct picture of the cells activity and its environment.It
10、 presents a powerful portrait,reflecting health,disease,aging and the effects of drugs and the environment.*Metabolomics-Anaidtounderstandingcellularbehavior*One method for extracting information is to separate and quantitate the compounds of the Metabolome.Following separation,the Metabolome may be
11、 profiled using a variety of techniques.For example,with a Metabolomics System,small molecules are measured by their selective oxidation(or reduction)across a series of flow-through electrochemical sensors.The result is an unique three-dimensional metabolic pattern,containing both known and unknown analytes that can now be used to characterize changes in the metabolome.
