Energy: catalysis and disorders of metabolism

• What are the major energy sources and pathways in metabolism?

  Glycolysis, TCA cycle, Beta oxidation
• What is the primary fuel molecule for ATP synthesis in most cells?

  Glucose
• Where do the oxidation pathways of fatty acids and glucose converge?

  On the TCA cycle in mitochondria
• What is the main source of energy in skeletal muscle during rest?

  Fatty acids
• What happens to glucose oxidation as exercise intensity increases?

  It surpasses fatty acid oxidation
• What is the role of ATP in energy production?

  Storage of free energy changes
• What are reducing equivalents produced for energy production?

  NADH and FADH2
• What is the function of the Pentose Phosphate Pathway?

  To produce NADPH for anabolism
• What is produced during glycolysis?

  Two pyruvates
• Where does the Krebs cycle occur?

  In the mitochondria matrix
• What is the main product of the Krebs cycle?

  CO2 and reduced electron carriers
• What drives ATP synthesis in chemiosmosis?

  Proton (H+) gradient
• What is the role of the Electron Transport Chain?

  To generate a proton gradient
• What is the final product of the Electron Transport Chain?

  Water (H2O)
• What is glycogen?

  A polysaccharide energy store of glucose
• What is the main enzyme for glycogen synthesis?

  Glycogen synthase
• What does glycogen branching enzyme do?

  Introduces branch points via α-1,6 linkages
• What is the role of glycogen debranching enzyme?

  Hydrolyzes α(1,6) linked residue
• What is glycogenolysis?

  The breakdown of glycogen
• What are symptoms of bioenergetic failure in muscle disorders?

  Hypoglycaemia and exercise intolerance
• What is a common symptom of metabolic myopathies?

  Impaired energy production
• What is the role of the liver in glucose homeostasis?

  Removes about 70% of glucose
• What happens to glycogen stores in muscle during exercise?

  Support local energy needs
• What is the consequence of GSD IV deficiency?

  Myopathy and dilated cardiomyopathy
• What is the effect of GSD V deficiency?

  Exercise-induced cramps and rhabdomyolysis
• What is the consequence of GSD VI deficiency?

  Fasting hypoglycaemia and hepatomegaly
• What is the role of creatine kinase in metabolic myopathy?

  Elevated serum indicates muscle breakdown
• What is myoglobinuria?

  Presence of myoglobin in urine
• What is the significance of PAS staining in muscle?

  Shows glycogen depletion in muscle
• What is the effect of GSD 0 liver defect?

  Normal enzyme activity found in muscle
• What is the consequence of GYG1 mutations?

  Can cause cardiomyopathy and arrhythmia
• What are the symptoms of metabolic myopathy?

  Hypotonia and multisystem involvement
• What is the role of the liver in glucose production?

  Only the liver supplies blood with glucose
• What is the primary function of glycogen phosphorylase?

  Cleaves α(1,4)-linked glucose
• What is the effect of lactic acidosis during fasting?

  Symptoms of hypoglycaemia
• What is the role of the brain in energy metabolism?

  Most energy-intensive organ
• What is the consequence of metabolic myopathy?

  Impaired energy production
• What is the significance of muscle glycogen depletion?

  Leads to exercise intolerance
• What is the role of GBE in glycogen synthesis?

  Introduces branch points to glycogen
• What is the effect of GSD III deficiency?

  Hypoglycaemia and myopathy