Govt. Exams
Entrance Exams
NADPH from the oxidative pentose phosphate pathway is essential for reductive biosynthesis of fatty acids and cholesterol, which occur predominantly in the fed state.
HFI results from aldolase B deficiency, preventing cleavage of fructose-1-phosphate into DHAP and glyceraldehyde, leading to accumulation and hepatotoxicity.
Von Gierke disease (GSD Type I) results from glucose-6-phosphatase deficiency, preventing final step of both gluconeogenesis and glycogenolysis, causing severe hypoglycemia.
Liver glycogen maintains blood glucose but cannot directly supply glucose-6-phosphate to other tissues as glucose-6-phosphate cannot cross cell membranes.
Muscle glycogen is the primary energy source during high-intensity exercise because muscle lacks glucose-6-phosphatase and retains glucose-6-phosphate for glycolysis.
Branching enzyme (amylo-1,6-transglucosidase) transfers segments of α-1,4-linked glucose chains to create α-1,6 branch points in glycogen.
Classical galactosemia results from galactose-1-phosphate uridyltransferase (GALT) deficiency, causing accumulation of galactose-1-phosphate and galactosylated proteins.
Glucose-1-phosphate is converted to UDP-glucose by UDP-glucose pyrophosphorylase, which is the activated form used by glycogen synthase for glycogen synthesis.
Von Gierke disease (GSD Type I) involves glucose-6-phosphatase deficiency, leading to impaired glucose release. However, alternative glucose production through gluconeogenesis and pentose phosphate pathway increases.
Glycogen has more frequent α-1,6 branch points (approximately every 8-12 glucose units) compared to starch, increasing its solubility and accessibility for enzyme action.
