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main glyco and kreb.pptx

  1. Glyco = sugar Lysis = splitting
  2. Dietary polysaccharides and disaccharides undergo hydrolysis to monosaccharides
  3. Glycolysis • Occurs in cytoplasm when glucose a hexose (6C) sugar is broken down into two molecules of pyruvate (3C) • Glycolysis involves ten individual steps, each catalysed by an enzyme. • Energy is released and there is a net production of 2 ATP molecules. • Reduced NAD is formed, which has the potential to produce more ATP. Glycolysis takes place in the cytosol of cells. Glucose enters the Glycolysis pathway by conversion to glucose-6-phosphate. H O OH H OH H OH CH2OPO3 2 H OH H 1 6 5 4 3 2 glucose-6-phosphate
  4. GLYCOLISIS • Glycolisis oxidation of glucose energy • It can function either aerobically or anaerobically pyruvate lactate • Occurs in the cytosol of all cell • AEROBICALLY GLYCOLYSIS : Pyruvate Mitochondria oxidized to Asetil CoA Kreb’s Cycle CO2 + H2O + ATP
  5. 2 Pyruvate (3C) Glucose (6C) 2 ATP 2 ADP 4 ADP 4 ATP 2 NAD 2 NADH + H
  6. • NADH + H+ and FADH2 enter ETC and produce; NADH + H+ 3 ATP FADH2 2 ATP c c Glycolysis complete Reaction (Energetic) Glucose  2Pyruvate + 2NADH+ 2ATP 2 NADH produce = 6 ATP ATP produce = 2 ATP x 2 = 4 Atp 2 ATP Used = - 2 ATP Total = 8 ATP
  7. Regulation of Glycolysis: Two types controls for metabolic reactions: a) Substrate limited : When concentrations of reactant and products in the cell are near equilibrium, then it is the availability of substrate which decides the rate of reaction. b) Enzyme-limited: When concentration of substrate and products are far away from the equilibrium, then it is activity of enzyme that decides the rate of reaction. These reactions are the one which control the flux of the overall pathway. There are three steps in glycolysis that have enzymes which regulate the flux of glycolysis. I. The hexokinase (HK) II. The phoshofructokinase (PFK) III. The pyruvate kinase
  8. Pyruvate is first transported into mitochondria via a specific transporter on the inner membrane and then oxidized to acetyl-CoA by the catalysis of pyruvate dehydrogenase complex.
  9. ATP
  10. Citric Acid cycle or Tricarboxylic Acid cycle (TCA) or Krebs Cycle
  11. 3 An overview of the citric acid cycle None of the intermediates are phosphorylated. None of the intermediates are phosphorylated All are either di- or tricarboxylic acids. To regenerate oxaloacetate. all are either di- or tricarboxylic acids.
  12. CO2 Acetyl CoA NAD+ Pyruvate NADH
  13. Overall Reaction: acetyl-CoA+3NAD++FAD+GDP+Pi+2H2O 2CO2 + 3NADH + FADH2 +GTP+2H++CoA Acetyl CoA 3 NAD 3 NADH + H 1 FAD 1 FADH2 1 ADP 1 ATP 2 CO2
  14. TCA cycle (Energetics): Acetyl CoA 2CO2 + 3NADH+ FADH2+ GTP 3 NADH produce = 9 ATP 1FADH2 produce = 2 ATP 1 GTP produce = 1 ATP 12 ATPs But 2 acetyl Con A take part in reaction so, 2 x 12ATPs = Toatal = 24 ATP formed
  15. Total yield of high energy ATP in the aerobic catabolism of glucose? Glycolysis: glucose 2pyruvate + 2NADH+2ATP 8 ATPs Pyruvate Dehydrogenase: 2pyruvate  2acetyl CoA + 2NADH 6 ATPs TCA cycle: acetyl CoA2CO2+3NADH+FADH2+GTP 2x12ATPs OVERALL yield from glucose 38 ATPs
  16. ENERGY RELATIONSHIPS  G° for oxidation of glucose to CO2 is 2,840 kJ/mole  Much of this energy conserved as ATP 38 ATP X 30.5 kJ/mole ATP =1,160 kJ/mole glucose  This represents 41% conservation of the potential energy available in glucose as ATP.