Term
|
Definition
| high density, low osmolar load, highly regulated |
|
|
Term
| the primary means by which blood sugar is kept in the normal range during and just after a meal is... |
|
Definition
| skeletal muscle glycogen synthesis |
|
|
Term
| glucose uptake in liver vs. skeletal muscle |
|
Definition
| in both, used for glycogen synthesis; liver - net glucose uptake and TG synthesis, muscle - insulin promotes uptake |
|
|
Term
| during a protein load, what keeps glucose in the normal range? |
|
Definition
| glucose released from hepatic glycogen |
|
|
Term
| core primer protein in glycogen |
|
Definition
| glycogenin. this catalyzes a 6-10 glucose molecule |
|
|
Term
|
Definition
| structural scaffold for the enzymes that regulate glycogen metabolism |
|
|
Term
| biochemical structure of glycogen |
|
Definition
| helical! alpha 1,4 linkages and 1.6 linkages for branches (beta linkage = flat, tightly packed chains = cellulose) |
|
|
Term
|
Definition
| the 4 residues left after you've reduced a straight chain as far as it can go |
|
|
Term
| add iodine to glycogen and you get... |
|
Definition
|
|
Term
| glycogen metabolism is used for acute storage of glucose in the fed state. glu-6-p usually... |
|
Definition
| is used locally, but the liver exports it. |
|
|
Term
| skeletal and cardiac muscle... |
|
Definition
| use glycogen as a store for energy used for muscle contraction |
|
|
Term
| regulation of glycogen metabolism |
|
Definition
| allosteric by metabolites and calcium. hormonal by camp-mediated hormones and insulin. |
|
|
Term
| primary cause of hyperglycemia in adult onset diabetes is |
|
Definition
| impaired skeletal muscle glucose disposal as glycogen |
|
|
Term
| glycogen chains are shortened by ______ which results in release of __________. catalyzed by _____ |
|
Definition
| phosphorolysis / glucose-1-phosphate / phosphorylase |
|
|
Term
| phosphorylase is specific for |
|
Definition
| alpha 1,4 glycosidic bonds |
|
|
Term
|
Definition
| glycogen(n-1)+glucose-1-p. reaction is isoenergetic, but there's so much Pi around that the reversibility is irrelevant |
|
|
Term
| reversible phosphorylation |
|
Definition
| phosphorylase is regulated (in response to hormones) between active and inactive forms |
|
|
Term
|
Definition
| catalyzed by debranching enzyme; moves 3 glucose molecules from one branch to another after phosphorylase does its thing |
|
|
Term
|
Definition
| after transferase, removes 1 glucose. catalyzed by debranching enzyme (which is a bifunctional enzyme). results in a straight non-branched chain |
|
|
Term
| a small amount of glycogen is degraded in ________ by __________. deficiency: _________. |
|
Definition
| lysosomes, alpha 1,4-glycosidase = acid maltase, Pompe Disease |
|
|
Term
|
Definition
| Type II Glycogen Storage Disease, fatal neonatal cardiomyopathy. acid maltase deficiency |
|
|
Term
| rate-limiting enzyme for glycogenesis / substrate |
|
Definition
| glycogen synthase / nucleotide-activated glucose |
|
|
Term
|
Definition
|
|
Term
| T/F: nucleotide activation releases energy |
|
Definition
| false - it requires energy |
|
|
Term
| non-rate-limiting enzymes involved in glycogen synthesis (2) |
|
Definition
| UTP-G1P transferase, brancher enzyme |
|
|
Term
| 5 principles of regulation of glycogen metabolism |
|
Definition
| 1. tissue specificity, 2. amplification of hormone signal, 3. organization into the functional unit of the glycogen particle, 4. multiple control points, 5. reciprocal regulation of synthase and phosphorylase |
|
|
Term
| liver vs. muscle - regulation of glucose trasnport |
|
Definition
| l - [glucose], m - [insulin] |
|
|
Term
| liver vs. muscle - fate of glucose derived from glycogen |
|
Definition
|
|
Term
| liver vs. muscle - stimulus for glycogenolysis |
|
Definition
|
|
Term
| hormonal regulation of glycogen metabolism (5) (draw diagram too) |
|
Definition
| phosphorylase is active when phosphorylated, synthase is inactive when phosphorylated, both are substrates for phosphorylase kinase which is active when phosphorylated, all three are substrates for type 1 protein phosphatase (PP-1) which is a major mediator of insulin action, and phosphorylase is NOT a substrate for PK-A (cAMP dependent protein kinase) |
|
|
Term
| regulation of glycogen synthase |
|
Definition
| 9 phosphorylation sites which are substrates for at least 7 kinases. critical sites are 3a-c and 4, which are substrates for gsk-3. phosphorylation influences substrate binding. also influences effector binding - sensitivity to stimulation by g1p. liver synthase DOES NOT have a camp-dependent kinase site, which is weird because camp is central to liver glycogen regulation. |
|
|
Term
| image of glycogen particles in a cell |
|
Definition
| glycogen = little black dots |
|
|
Term
|
Definition
| atp+calcium=activation of phosphorylase kinase and phosphorylase in skeletal muscle. once available ATP is used up, activity returns to baseline, indicating presence of functional PP-1. ALL of the regulated enzymes are phosphorylated. |
|
|
Term
| allosteric effects on hepatic phosphorylase, the "glucose receptor in liver". how do these affect it- glycogen, glucose, AMP, ATP, glu6p, udp-glucose, ser14p. |
|
Definition
| activation: glycogen, AMP, ser14p (hormonally). inactivation: glucose. inhibition: ATP, g6p, udp-glucose. |
|
|
Term
| type I glycogen storage disease: symptoms, treatment, mechanism |
|
Definition
| hepatomegaly (fatty liver), metabolic acidosis, low blood sugar, high blood lactate, lipemic serum, fat lobules on skin. treatment: IV dextrose (acute) and raw corn starch (chronic). g6phosphatase deficiency (like normal muscle!) = HMP shunt makes a lot more fatty acids, activated by nadp. |
|
|
Term
| oxidative reactions in 5p pathway for... (4) |
|
Definition
| production of NADPH for FA synthesis, steroid synthesis, co-factor for antioxidants. |
|
|
Term
| non-oxidative reactions in 5p pathways for (2) |
|
Definition
| production of ribose 5p for nucleotide synthesis, metabolism of diet-derived 5c sugars |
|
|
Term
|
Definition
|
|
Term
| 5p pathway: what does in, what comes out |
|
Definition
| in: g6p, out: nadph, ribose 5p. (g6p refers to alternative name: hexose monophosphate shunt) |
|
|
Term
|
Definition
| rate-limiting enzyme:g6p dehydrogenase (G6PD). allosteric activation by nadp and inactivation by nadph. |
|
|
Term
|
Definition
| the most common enzyme deficiency in the world. causes hemolytic anemia because of impaired free radical detoxification in erythrocytes. hemolytic crises occur upon exposure to oxidants: infection, fava beans, oxidant drugs AAA (antibiotics, antipyretics, antimalarials) |
|
|
Term
|
Definition
| step 1: phosphorylation, catalyzed by hexokinase (but Km is too high) and fructokinase (in the liver). product is fructose1p. cleaved to glyceraldehyde and dihydroxyacetone-P by aldolase B |
|
|
Term
|
Definition
| benign deficiency of fructokinase |
|
|
Term
| hereditary fructose intolerance |
|
Definition
|
|
Term
|
Definition
| product of fructose metabolism from f1p, can pass down gluconeogenic or glycolytic pathways. |
|
|
Term
|
Definition
| product of fructose metabolism from f1p, is an intermediate in glycolysis |
|
|
Term
|
Definition
| step 1: phosphorylation catalyzed by galactokinase to make galactose1p. then galactose1p uridyltransferase makes udp-gal (nucleotide activation step). |
|
|
Term
|
Definition
| product of galactose metabolism from gal1p. important substrate for synthesis of critical macromolecules: lactose, GAGs, GPs, glycolipids |
|
|
Term
|
Definition
| deficiency of gal1p uridyl-transferase. liver disease and bacterial sepsis in newborns. |
|
|
Term
|
Definition
| b-galactose+glucose (beta1,4 linkage). catalyzed by lactose synthase (UDP-g:g g). takes place in mammary glands. |
|
|
Term
|
Definition
| hydrolyzes lactose to produce glucose plus galactose. expressed in intestinal brush border. / lactose intolerance |
|
|
Term
|
Definition
| first thick line = glycogen phosphorylase, second thinner line = glycogen synthase |
|
|
