glycogen metabolism P2. Flashcards
Whyy have glycogen store when fat gives more energy?
- fat has more C than sugar… so adds to E difference..
- fat also gives more E, bc it is reduced to C and H bonds only… compared to glucose, way more reduced
why not use fat then?
1. takes a long time to mobilize fat and cant metabolize fat without O2 (done in the mitochondria, which doesnt work without O2)
glycogen particle
exist as cytoplasmic granuole… with the necessary enzymes to break make and regulate… but does not contain ALL of the regulatory enzymes
glycogen contains
a lot of glucose units, and they are mostly linked a(1-4), byut every 8-12 glucose units is an a(1-6) branch, this allows for branched structure.
nonreducing end and reducing end
reducing end = has a hemiacetal
structure of glycogen
- branched structure, why not linear?
can have simultaneous breakdown at non-reducing ends (acetal portion, removing sugar by phosphorolysis)… on every single nonreducing ends, can use phosphorylase pulling off glucose units. allows you to rapidly use glucose, which is good.
3 enzymes involved in glycogen breakdown pathway
glycogen phosphorylase (GP… technically PH, but GP easier to remember), wil catalyze rds which is a phosphorolysis… negative ∆G in body.
debranching Enzyme (DBE), hydrolyze a(1-6) linkage
Phosphoglucomutase (PGlucM) converts G1P to G6P, which can be used in many pathways. Muscle = glyc Liver = dumping gluc into blood stream.
what is phosphorolysis
breaking with Pi as the breaking agent.
glycogen phosphorylase
key regulatory enzyme with very complex regulation
products are G1P (synthesis and breakdown) and a glycogen chain shorter by 1 gluc unit