The overview of metabolism by 2eV8w9

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									The overview of metabolism

  Associate professor Shi-Jie Liu,Ph D.
  Department of clinical pharmacology,
       Xinqiao hospital, TMMU.
An open system:Exchange mass and energy
ΔS surrounding+ΔS system>0,
biology capture negative entropy from surrounding
Metabolism: The total of all chemical reactions in an
             organism
Purposes: To acquire free energy
          To acquire reduction potential
          To synthesize the structure unit molecules
The design of metabolism
• The amount of reactions in metabolism is
  large, but the kind is small and the
  mechanisms are similar
• A lot of       molecules are involved in
  metabolism, but only a few of molecules
  play key roles in metabolism
• The different metabolic pathways are
  controlled by similar mechanism
The design of biochemical reactions

• Impossibilities of thermodynamics: Almost
  biochemical reactions do not spontaneously
  process without extra free energy
• Impossibilities    of    kinetics:  Almost
  biochemical reactions do not actually occur
  without catalysis of enzymes
• Enzymes: Control almost biochemical
  reactions.
 The role of enzymes in metabolism

• Enzymes can’t change the direct of reactions,
  but decrease active enery of reactions
• Pacemaker enzyme(or regulate enzyme):
  An enyme that catalyzes a committed step in
  a biochemical pathway
• Anabolism: Large complex molecules are synthesized from smaller
  molecules.
• Catabolism: Large complex molecules are degraded into smaller and
  simpler products
• These two pathways are completely difference
The intermediate molecules

•   ATP: the energy currency
•   NADH/NADPH: the carrier of electrons
•   Coenzyme A: the carrier of acyl
•   Biotin: the carrier of CO2
•   Isopentenyl pyrophosphate: the carrier of
    five-carbon structural units.
ATP+H2O=ADP+Pi
ΔGº’=-7.3 kJ/mol
ATP+H2O=AMP+PPi
ΔGº’=-32.2 kJ/mol
PPi+ H2O=2Pi
ΔGº’=-32.2 kJ/mol
Phosphate group transfer potential: the tendency of a
phosphorylated molecule to undergo hydrolysis
In cell: 500=[ATP]/[ADP][Pi]
The compartmentation of
metabolism in eukaryote cell

  • Glycolysis: all in cytoplasm
  • Gluconeogenesis: Pyruvate carboxylase in
    mitochondria
  • Citric acid cycle: all in mitochondria
  • Fatty acid breakdown: all in mitochondrial
    matrix
  • Fatty acid synthesis: all in cytoplasm
• Stage 1: The major
  nutrient molecules are
  degraded to building block
  molecules

• Stage 2:The building
  block    molecules    are
  converted to a small
  number      of    simpler
  molecule,such as acetyl-
  CoA

• Stage3: The acetyl group
  of acetyl-CoA enters the
  citric acid cycle and is
  completely oxidized.
The regulation of metabolism
• The amount of enzyme in metabolism is
  controlled
• The activity of enzyme is controlled by:
   – Allosteric regulation
   – Covalent modification
   – Compartmentation
• The anabolic and catabolic pathways are
  completely difference
• Many reactions are controlled by state of energy.
Summary

• The system of living organism
• Metabolism, anabolic and catabolic pathway
• The purposes of metabolism
• The design of reactions in thermodynamics
  and kinetics
• Three stages of energy captured from food
• The regulation of metabolism
Key words

• System of living organism
• Metabolism; Anabolism; Catabolism
• Genetic control, Allosteric regulation,
  Covalent modification, Compartmentation
• ATP; NADH/NADPH; Biotin; Coenzyme
  CoA; Actyl-CoA; Isopentenyl pyrophosphate
Thanks

								
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