Sugar Metabolism Flashcards
Describe prepatory phase of glycolysis
Phosphorylation of glucose and its conversion to glyceraldehyde 3 phosphate
Payoff phase of glycolysis
Oxidative conversion of glyceraldehyde 3 phosphate to pyruvate and coupled formation of ATP to NADH
What are fates of pyruvate?
TCA cycle, LDH, fermentation, biosynthesis
What are high energy enzymes used in gluconeogenesis to bypass pyruvate kinase?
Pyruvate carboxylase and PEP carboxykinase
What is the cofactor uses in pyruvate carboxylase?
Biotin
What does biotin do?
Adds Carboxyl group to pyruvate to make oxaloacetate
What two molecules signal low energy?
AMP and ADP
At high amounts of AMP what tissue favors glycolysis?
Muscle tissue
At low AMP what tissue does not favor glycolysis?
Liver
Which molecule is the transfer for reducing equivalents?
Malate
What are the four bypass enzymes of gluconeogenesis?
Pyruvate carboxylase, PEP carboxykinase, F16BP, glucose 6 phosphotase
What molecule inhibits F16BP?
AMP
What converts oxaloacetate to PEP?
PEP carboxykinase
If lactate is starting source for gluconeogenesis, is malate needed?
No it creates its own reducing equivalents in the cytosol and uses a isozyme of PEP carboxykinase in the mitochondria
What is the net result of the pentode phosphate pathway?
2 NADPH, ribose 5 phosphate, co2 and two protons
What inhibits PFK 1?
ATP, citrate
What allosterically activates PFK1?
Fructose 26 Bisphosphate and amp
Insulin leads to what kind of cascade?
Dephosphorylation
Glucagon leads to what kind of cascade?
Phosphorylation
What is the substrate for PFK2/FBPase2
Fructose 6 phosphate
Xylulose 5 phosphate activates what metabolic pathway by stimulating which enzyme?
Glycolysis and PFK2/FBPase2
In liver if glucagon goes up, what happens to pyruvate kinase?
It is phosphorylated and inhibited
What inhibits Pyruvate Kinase?
ATP, Acetyl-CoA, long chain Fatty acids, alanine
What is a phosphorylase?
Enzyme using inorganic phosphate to break a bond
Glycogen phosphorylase makes what molecule?
Glucose 1 phosphate
What hormone activates glycogen breakdown?
Epinephrine
What are benefits to glycogen phosphorolysis?
Glucose 6 phosphate is made without ATP, 1 ATP is used in predatory phase of glycolysis, there is a net gain of 3 ATP for glycolysis
What does phosphoglucomutase do?
Catalyzes glucose 1 phosphate to glucose 6 phosphate
What is the difference in glycogen breakdown in liver and muscle?
In liver glycogen will put glucose in blood. In muscle it is used for glycolysis
In the liver what enzyme is needed for glucose to leave the cell?
Glucose 6 phosphotase
Which tissue has two forms of glycogen phosphorylase?
Muscle. Phosphorylase a is active. Phosphorylase b not as active
cAMP activates which enzyme to stimulate glycogen breakdown in muscle?
PKA. Stimulates glycogen breakdown
cAMPincreases in response to what hormones?
Epinephrine and glucagon
When is glycogen synthase active?
When it is dephosphorylated
When is glycogen synthase inactive?
When it is phosphorylated by GSK3
