生化

这是一篇关于生化的思维导图，主要内容有1.Chemical structure2.Biosignificance of Carbohydrates3.Elemental composition等。

Chapter 8 Carbohydrates Metabolism

• §1 Overview
  • 1. Chemical structure
    • 1）polyhydroxy aldehydes
    • 2) polyhydroxy ketones
  • 2. Biosignificance of Carbohydrates
    • 1) major source of carbon atoms and energy
    • 2) Supplying a huge array of metabolic intermediates
    • 3) The structural elements in cell coat or connective tissues
  • 3. Elemental composition
    • Cx(H2O)y
  • 4.Classification
    • 1）Classified by the number of Monosaccharide
      • Monosaccharide: the smallest unit of sugar that cannot be hydrolyzed
      • Oligosaccharide:2-10
      • Polysaccharide:>10
    • 2）Classified by functional groups
      • Aldose
      • Ketose
• §2 Anaerobic glycolysis [①glucose →2lactic acid (lack of O2) ②All of the enzymes of glycolysis locate in cytosol.]
  • 1. The procedure of anaerobic glycolysis
    • 1) Glycolytic pathway : G → pyruvate including 10 reactions
      • • （1）G phosphorylated into G-6-P
      • • （2）G-6-P → fructose 6-phosphate
      • • （3）F-6-P → fructose 1,6-bisphosphate
      • • （4）F-1,6-BP → 2 Triose phosphates
      • • （5）Triose phosphate isomerization
      • • （6） Glyceraldehyde 3-phosphate → glycerate 1,3-bisphosphate
      • • （7）1,3-BPG → glycerate 3-phosphate
      • • （8）Glycerate 3-phosphate → glycerate 2- phosphate
      • • （9）Glycerate 2-phosphate → phosphoenol pyruvate
      • • (10) PEP →pyruvate
    • 2) Pyruvate → lactate
  • 2.Regulation of Glycolysis [Three key enzymes catalyze irreversible reactions : Hexokinase, Phosphofructokinase & Pyruvate Kinase.]
    • 1) PFK-1 (the rate-limiting step of the Glycolysis pathway)
    • 2) Pyruvate kinase
    • 3) Hexokinase and glucokinase
  • 3. Significance of glycolysis
    • 1) Glycolysis is the emergency energy- yielding pathway.
    • 2) Glycolysis is the main way to produce ATP in some tissues.
• §3 Aerobic Oxidation of Glucose
  • 1. Process of aerobic oxidation
    • 1) Oxidative decarboxylation of Pyruvate to Acetyl CoA
      • irreversible
      • in mitochodria.
    • 2) Tricarboxylic acid cycle(TAC)
      • The net reaction of the TAC: acetylCoA+3NAD++FAD+GDP+Pi+2H2O → 2CO2+3NADH+3H++FADH2+GTP+ HSCoA
      • Irreversible and aerobic reaction
      • The enzymes are located in the mitochondrial matrix.
  • 2. ATP produced in the aerobic oxidation
    • 1）acetyl CoA → TAC : 3 (NADH+H+) + FADH2 + 1 GTP → 10 ATP
    • 2）pyruvate →acetyl CoA: NADH+H+ → 2.5 ATP
    • 3）1 G→2 pyruvate:2 (NADH+H+)+2 ATP →5 or 7 ATP
  • 3. The regulation of aerobic oxidation
    • The Key Enzymes of glycolysis
      • Pyruvate Dehydrogenase Complex
      • Citrate synthase
      • Isocitrate dehydrogenase (rate-limiting )
      • a-Ketoglutarate dehydrogenase
• §7 Blood Sugar and Its Regulation
  • 1. The source and fate of blood sugar
    • 1）source
      • dietary supply
      • liver glycogen
      • non-carbohydrate (gluconeogenesis)
      • other saccharides
    • 2）fate
      • CO2 + H2O + energy
      • glycogen
      • other saccharides
      • non-carbohydrates (lipids and some amino acids)
  • 2. Regulation of blood sugar level
    • 1）insulin
      • decreasing blood sugar levels
    • 2）glucagon
      • increasing blood sugar levels
    • 3）glucocorticoid
      • increasing blood sugar levels
    • 4）adrenaline
      • increasing blood sugar levels
  • 3. Abnormal Blood Sugar Level
    • 1）Hyperglycemia: > 7.22~7.78mmol/L
    • 2）The renal threshold for glucose: 8.89~10.00mmol/L
    • 3）Hypoglycemia: < 3.33~ 3.89mmol/L
• §6 Gluconeogenesis
  • 1. Gluconeogenic pathway
    • 1) The shunt of carboxylation of Pyr
    • 2) F-1, 6-BP →F-6-P
    • 3) G-6-P →G
  • 2. Regulation of gluconeogenesis
    • 1）Substrate cycle
    • 2）futile cycle
  • 3. Key enzymes of gluconeogenesis
    • 1) PEP carboxykinase
    • 2) Pyr carboxylase
    • 3) Fructose-bisphosphatase
    • 4) Glucose-6-phosphatase
  • 4. Significance of gluconeogenesis
    • 1) Replenishment of Glucose by Gluconeogenesis and Maintaining Normal Blood Sugar Level
    • 2) Replenishment of Liver Glycogen
    • 3) Regulation of Acid-base Balance
• §5 Glycogen synthesis and catabolism
  • 1. Glycogen synthesis (Glycogenesis) [occurs in cytosol of liver and skeletal muscle mainly]
    • 1）key E
      • Glycogen synthase
    • 2）primer
      • Glycogenin
    • 3) glycogen anabolism
      • 1 G consumes 2~P
    • 4)UDPG
      • G active pattern, G active donor
    • 5) enzyme
      • Branching enzyme
  • 2.Glycogen catabolism (glycogenolysis) [There is no the activity of glucose 6- phosphatase (G-6-Pase) in skeletal muscle.]
    • 1)key E
      • Phosphorylase
    • 2)end products
      • 85% of G-1-P and 15% of free G
    • 3)enzyme
      • Debranching enzyme
  • 3. Regulation of glycogenesis and glycogenolysis
    • 1) Allosteric regulation
    • 2) Covalent modification
• §4 Pentose Phosphate Pathway
  • 1. The procedure of pentose phosphate pathway/shunt [In cytosol]
    • 1) Oxidative Phase
    • 2) Non-Oxidative Phase
      • Transketolase: requires TPP
      • Transaldolase
  • 2. Regulation of pentose phosphate pathway [Glucose-6-phosphate Dehydrogenase is the rate-limiting enzyme]
    • NADPH/NADP+↑, inhibit NADPH/NADP+↓, activate
  • 3. Significance of pentose Phosphate pathway
    • 1) To supply ribose 5-phosphate for biosynthesis of nucleic acid
    • 2) To supply NADPH as H-donor in metabolism