NME 2.28 Flashcards
describe processes of glycogen metabolism in fed state?
- insulin and glucose-6-phosphate activate synthase phosphate
- synthase phosphatase activates glycogen synthase
- glycogen synthase catalyzes the elongation of glycogen chain in UDP-glucose as substrate
describe processes of glycogen metabolism in fasting state?
- liver glycogen is source of blood glucose
- muscle glycogen is metabolised by glycolysis to generate energy
- glucagon and adrenaline activate synthase kinase which inactivate glycogen synthase
what activates synthase phosphatase?
- insulin and glucose 6-P
what activates glycogen synthase?
- synthase phosphatase
what inactivate glycogen synthase?
- synthase kinases
what activates synthase kinases?
- glucagon
- adrenaline
what does glycogen phosphorylase catalyse?
- degradation of glycogen to glucose 1-P through phosphorolysis
what activates glycogen phosphorylase?
phosphorylase kinase
what activates phosphorylase kinase?
activated by glucagon and adrenaline
what inactivates glycogen phosphorylase?
phosphorylase phosphatase
what activates phosphorylase phosphatase?
insulin and glucose
which one convert UDP glucose to glycogen?
glycogen synthase
which one converts glycogen to G1P
glycogen phosphatase
what are all kinases activated by?
glucagon and adrenaline
acronym: KAG
what are all phosphatase activated by?
insulin and glucose
acronym: PIG
describe the consequences of defective glycogen metabolism
- reduce liver ability to replenish blood glucose levels
- restrict energy production in muscles leading to fatigue
what are the requirements for gluconeogenesis?
- lactate
- amino acids
- glycerol
- fatty acid oxidation
what regulates gluconeogenesis?
- inhibited by insulin
- stimulated by glucagon and fatty acids
what is the role of gluconeogenesis?
- maintain blood glucose when the liver glycogen is depleted
outline gluconeogenesis?
- reverse conversion
- pyruvate to oxaoacetate to malate to oxaloacetate then to phosphoenolpyruvate to fructose 1,6 to fructose 6-P then to glucose 6-P then glucose
what does pyruvate carboxylase do?
convert pyruvate to oxaloacetate
what does phosphoenolpyruvate carboxykinase do?
convert oxaloacetate to phosphoenolpyruvate
what does Fructose 1,6-biphosphate
convert fructose 1,6-P to cfructose 6-P
what is the cori cycle?
- when lactate is converted to glucose in liver through gluconeogenesis
- glucose is used by muscle to form lactate
describe gluconeogenesis from amino acids?
- protein is used in muscle to produce amino acids through proteolysis
- amino acids is converted to pyruvate then pyruvate is converted to glucose in liver
what amino acids cannot be used for gluconeogenesis?
- leucine and lysine
describe gluconeogenesis from glycerol?
- glycerol released from breakdown of triglyceride in adipose tissue during fasting
- taken up by licer
- converted to glucose by gluconeogenesis
what are the key enzymes used for glycolysis?
- glucokinase
- phosphofructokinase
- pyruvate kinase
what enzymes are used for gluconeogenesis?
- glucose 6-phosphatase
- fructose 1,6-biphosphatase
- pyruvate carboxylase
- PEP carboxykinase
describe how dietary carbohydrates can be converted to triaglycerides in liver?
- glucose converted to pyruvate through glycolysis
- pyruvate converted to acetyl CoA
- then converted to citrate
- citrate is converted back to acetyl CoA
- acetyl CoA converted to malonyl CoA
- then to fatty acid
what happens at high concentration of malonyl CoA?
- inhibits oxidation of fatty acid
what happens at low concentration of malonyl CoA?
- stimulate oxidation of fatty acid
does malonyl CoA need energy to form fatty acid?
yes, energy taken from NADPH
which process synthesized NADPH?
pentose-phosphate pathway
what activates pyruvate dehydrogenase and acetyl-CoA carboxylase?
activated by insulin
what inhibits acetyl CoA carboxylase?
- inhibited by glucagon and fatty acid
what inhibits pyruvate dehydrogenase?
- inhibited by fatty acids and NADH
NADPH is required for?
- fatty acid synthesis
- fatty acid chain elongation
- cholestrol biosynthesis
- cytochrome P450 monoxygenases
- reduction of oxidised glutathione
