WHILE YOU READ BIOCHEMISTRY SCAN FOR THE FOLLOWING Metabolic tips

1. Three compulsory lists that must be at your tips-

· Ketogenic and Glucogenic amino acids.

· Essential and Nonessential amino acids.

· Basic, Acidic, Sulphur containing amino acids.

2. Regulatory Enzymes of pathways e.g.

· Citrate synthesis in citric acid cycle.

· Phosphofructokinase in Glycolysis.

· Pyruvate dehydrogenase in Pyruvate Oxidation.

· Pyruvate Carboxykinase in Gluconeogenesis.

· Glycogen Synthase in Glycogenesis.

· Phosphorylase in Glycogenolysis.

· G6PD in PPP.

· HMG CoA reductase in cholesterol synthesis.

3. Search for ATP estimates e.g.,

· 8 ATP’s per Glucose molecule in Glycolysis under aerobic conditions.

· 30 ATP’s per Pyruvate molecule entering citric acid cycle.

· 129 ATP’s per palmitate undergoing b-oxidation.

4. Look for regulatory molecules and feedback inhibitions e.g.,

· Glucose-6-phosphate inhibition on hexokinase.

· Citrate’s inhibitory effect on phosphofructokinase 1.

· Alanine’s inhibitory effect on Pyruvate kinase.

· Acetyl CoA’s inhibitory effect on Pyruvate dehydrogenase.

· Long chain acyl CoA’s inhibitory effect on Acetyl CoA carboxylase.

5. Look for subcellular organelles where the reactions specifically occur.

· Enzymes of citric acid cycle in mitochondrial matrix.

· Enzymes of Glycolysis in cytosol.

· Enzymes of pentose phosphate pathway in cytosol.

· Enzymes of denovo synthesis of fatty acids in cytosol.

· Enzymes of fatty acid oxidation in mitochondria.

6. Always have a clarity regarding precise role of various lipoproteins.

· HDL is cholesterol scavenger.

· Chylomicrons carry dietary cholesterol.

· VLDL are vehicles of transport of triacylglycerol from the liver to extrahepatic tissues.

7. Vitamins and their role as coenzymes e.g.,

· Thiamine in oxidative decarboxylation.

· Niacin in dehydrogenase reactions.

· Pantothenic acid in CoA.

· Pyridoxal phosphate in muscle phosphorylase.

· Biotin in carboxylase enzymes.

· Vitamin B12 to produce succinyl CoA.

· Folate in transfer of one-carbon units.

8. Products that accumulate in metabolic disorders e.g.,

· Homogenisate in urine of Alkaptonuria patients

· Phenyl acetyl glutamine in phenylketonuria.

· Xanthurenate in Vitamin B6 deficiency.

· Branched chain ketonuria in Mapple syrup urine disease.

9. Check for key enzymes responsible for Metabolic disorders e.g.,

· Glucose-6-phosphates in von Gierkes.

· Hepatic fructokinase in essential fructosuria.

· Galactose-1-phosphate uridyl transferase in Galactosemia.

· Cystathionine-b-synthase in homocystinuria.

10. Where nadh forms, where NADPH forms, where FADH₂ forms, where substrate level phosphorylation occurs e.g.,

· FADH₂ in succinate dehydrogenase in citric acid cycle.

· NADH in all degradative reactions.

· NADPH in all synthetic reactions.

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Metabolic tips