Glycogen Catabolism Flashcards
what are the most significant contributors to glycogen catabolism?
the storage polysaccharides glycogen and starch
who made important discoveries in glycogen catabolism?
the Coris
what is glycogen?
a large polymer of glucose in a1-4 and a1-6 linkages
what is glycogens structure?
12 tiers in mature glycogen with 55,000 glucose residues build on glycogenin protein
20-40 particles come together → large alpha rosettes of glycogen granules
what does glycogen do?
storage form of glucose
important in maintaining constant blood glucose
primarily stored in liver and skeletal muscle
what is the main catabolic enzyme for glycogen and what does it do?
glycogen phosphorylase removes terminal glucose residues from the non reducing end by phosphorolysis
what is the pathway for glycogen metabolism in liver?
glucose-6-phosphatase –> glucose –> blood/tissues and used for energy
what is the pathway for glycogen metabolism in muscle?
enters glycolysis where it is used for quick source of energy during vigorous activity
how are glycogen storage diseases usually inherited?
autosomal recessive manner
what do glycogen storage diseases result in?
enlarged liver, muscle wasting and metabolic problems
how are glycogen storage diseases treated?
very low glucose intake and monitored carbohydrate diet
what is gluconeogenesis?
new formation of glucose
what is glucose synthesised from?
simple non-carb precursors such as 3C lactate, pyruvate and glycerol, glucogenic amino acids
what are the 3 irreversible steps of gluconeogenesis?
Step 1: to convert pyruvate to phosphoenolpyruvate
Step 7: to convert fructose 1,6 bisphosphate to fructose 6-phosphate
Step 10: to convert glucose 6-phosphate to glucose
what is the primer protein that glycogen is synthesised on?
glycogenin
