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Dental Biochemistry Review

Dental Biochemistry Review. CHO and N Metabolism; Molecular Biology. Free energy of a reaction. The free energy change ( D G ) of a reaction determines its spontaneity. A reaction is spontaneous if D G is negative (if the free energy of products is less than that of reactants). .

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Dental Biochemistry Review

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  1. Dental Biochemistry Review CHO and N Metabolism; Molecular Biology

  2. Free energy of a reaction The free energy change (DG) of a reaction determines its spontaneity. A reaction is spontaneous if DG is negative (if the free energy of products is less than that of reactants). DGo' = standard free energy change (at pH 7, 1M reactants & products); R = gas constant; T = temp.

  3. “High energy” bonds Phosphoanhydride bonds (formed by splitting out H2O between 2 phosphoric acids or between carboxylic & phosphoric acids) have a large negative DG of hydrolysis.

  4. BIOENERGETICS SUMMARY • Actual (NOT Standard) Free Energy Change determines reaction spontaneity • Enzyme reactions may be coupled to promote reaction spontaneity • Free energy is released by hydrolysis of “high energy” molecules (e.g. ATP) • Reduced coenzymes (e.g. NADH, FADH) are energy-rich compounds

  5. Metabolism of Glucose Catabolic Pathways: Glycolysis (Glucose  Pyruvate + ATP) Citric Acid (TCA) (+ oxidative phosphorylation) Pentose Phosphate Shunt Glycogenolysis Anabolic Pathways: Gluconeogenesis Glycogenesis

  6. Phosphofructokinase is usually the rate-limiting step of the Glycolysis pathway. Phosphofructokinase is allosterically inhibited byATP. • At low concentration, the substrate ATP binds only at the active site. • At high concentration, ATP binds also at a low-affinity regulatory site, promoting the tense conformation.

  7. Glycogen Synthesis • Ingestion of abundant carbohydrates • Blood [glucose] increase • Secretion of insulin • GLUT 4 translocation • Activation of Glycogen Synthase • Inactivation of Glycogen Phosphorylase

  8. Glycogen Degradation Precondition: Low blood glucose Epinephrine (immediate energy need) Glucagon (need for glucose homeostasis) Liver exports glucose Muscle metabolizes Glucose-6-P

  9. Actions of Insulin and Glucagon Metabolic Pathway InsulinGlucagon Glucose Uptake Increased Glycolysis Increased Decreased Gluconeogenesis Decrease Increased Glycogenesis Increased Decreased Glycogenolysis Decreased Increased

  10. Citric Acid (TCA) Cycle and Electron Transport Complete oxidation of glucose to CO2 + H2O Oxidative Phosphorylation (ATP generation)

  11. Biosynthetic “Families” of Amino Acids and their Metabolic Precursors PrecursorAmino Acid(s) α-ketoglutarate Glu (E), Gln (Q), Pro (P), Arg (R) Oxaloacetate Asp (D), Asn (B), Met (M),Thr (T), Ile (I), Lys (K) 3-phosphoglycerate Ser (S), Cys (C), Gly (G) PEP + Erythrose-4-P Phe (F), Tyr (Y), Trp (W) Pyruvate Ala (A), Val (V), Leu (L) Ribose-5-P His (H)

  12. Urea Cycle Purpose: Disposal of Nitrogen (ammonia) Urea: the main nitrogenous end product in mammals A source of amino acid (Arginine)

  13. Amino Acid Derivatives Amino AcidDerivativeFunction Histamine Histidine Vasodilation Tyrosine Thyroxine Iodine carrier Nor/Epinephrine Hormone(s) DOPA Neurotransmitter Dopamine Neurotransmitter Tryptophan Serotonin Neurotransmitter Melatonin Pigment

  14. Synthesis of Heme and Hemoglobin

  15. Purine Nucleotide Biosynthesis: PRPP to Inosine monophosphate Inosine monophosphate (IMP) H2O formyl-THF fumarate ATP glycine Ring closure asp formyl-THF ATP ATP gln CO2 ATP ATP Ring closure

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