BIOC 3621: FINAL EXAM QUESTIONS AND
VERIFIED ANSWERS
How is Glycogen formed from Glucose - answer -requires energy (supplied by UTP
hydrolysis)
-UDPG formed
How is UTP replenished - answer -an exchange reaction
UDP + ATP --> UTP + ADP
How is Glycogen phosphorylase controlled - answer -allosteric control
-covalent modification
-inhibitor: glucose (favors T state)
Phosphorylase kinase (uses 2 ATP) produces phosphorylase a
Phosphrylase phosphatase (uses 2 H2O) produces phosphorylase b
Glycogen synthase - answer -allosteric control
-covalent modification
-activators: hormonoal signals (glucagon or epinephrine)
-after phosphorylatin, becomes inactive
-dephosphorylation by phosphoproteinphsphatase
Gluconeogenesis - answer pyruvate --> Glucose
-differs in Glycolysis step 10, 3, and 1(the irreversible steps)
What happens at the beginning of Gluconeogenesis - answer Pyruvate carboxylated to
oxaloacetate
-needs biotin (CO2 carrier)
allosteric control
-activated by Acetyl CoA
Gluconeogenesis Step 10 - answer Oxaloacetate to phosphoenolpyruvate
-uses GTP
, -Enzyme = PEPCK
-releases CO2
Gluconegenesis Step 3 - answer Fructose 1,6 bisphosphate to Fructose 6 Phosphate
-enzyme: Fructose 1,6 bisphosphatase
Allosteric control
-Activated by ATP
-inhibited by AMP
Gluconeogenesis Step 1 - answer Glucose 6 phosphate to Glucose
-enzyme = glucose 6 phosphatase
Fructose 2, 6 bisphosphate - answer Allosteric control
-activates PFK
-inhibits FBPase
high concentration stimulates glycolysis
low concentration stimulates gluconeogenesis
Concentration of F2, 6P depends on balance between synthesis and breakdown
Substrate cycling - answer opposing reactions can be catalyzed by different enzymes
and each opposing enzyme can be regulated independently
Cori Cycle - answer cycle of glucose due to glycolysis in muscle and gluconeogenesis in
liver
Describe glycolysis in fast twitch muscle - answer Fewer mitochondria = anaerobic
metabolism = buildup of lactate = muscle aches
Gluconeogenesis recycles the lactate (first oxidized to pyruvate)
What is the overall reaction of the Cori Cycle - answer 2ATP + 2GTP + 4H2O -->2ADP + 2
GDP + 4P
Liver Pyruvate Kinase - answer -phosphorylation = less active
What are the control points in glycolysis - answer Hexokinase
-inhibited by high levels of Glucose 6 phosphate
Pyruvate Kinase
-inhibited by ATP and alanine
VERIFIED ANSWERS
How is Glycogen formed from Glucose - answer -requires energy (supplied by UTP
hydrolysis)
-UDPG formed
How is UTP replenished - answer -an exchange reaction
UDP + ATP --> UTP + ADP
How is Glycogen phosphorylase controlled - answer -allosteric control
-covalent modification
-inhibitor: glucose (favors T state)
Phosphorylase kinase (uses 2 ATP) produces phosphorylase a
Phosphrylase phosphatase (uses 2 H2O) produces phosphorylase b
Glycogen synthase - answer -allosteric control
-covalent modification
-activators: hormonoal signals (glucagon or epinephrine)
-after phosphorylatin, becomes inactive
-dephosphorylation by phosphoproteinphsphatase
Gluconeogenesis - answer pyruvate --> Glucose
-differs in Glycolysis step 10, 3, and 1(the irreversible steps)
What happens at the beginning of Gluconeogenesis - answer Pyruvate carboxylated to
oxaloacetate
-needs biotin (CO2 carrier)
allosteric control
-activated by Acetyl CoA
Gluconeogenesis Step 10 - answer Oxaloacetate to phosphoenolpyruvate
-uses GTP
, -Enzyme = PEPCK
-releases CO2
Gluconegenesis Step 3 - answer Fructose 1,6 bisphosphate to Fructose 6 Phosphate
-enzyme: Fructose 1,6 bisphosphatase
Allosteric control
-Activated by ATP
-inhibited by AMP
Gluconeogenesis Step 1 - answer Glucose 6 phosphate to Glucose
-enzyme = glucose 6 phosphatase
Fructose 2, 6 bisphosphate - answer Allosteric control
-activates PFK
-inhibits FBPase
high concentration stimulates glycolysis
low concentration stimulates gluconeogenesis
Concentration of F2, 6P depends on balance between synthesis and breakdown
Substrate cycling - answer opposing reactions can be catalyzed by different enzymes
and each opposing enzyme can be regulated independently
Cori Cycle - answer cycle of glucose due to glycolysis in muscle and gluconeogenesis in
liver
Describe glycolysis in fast twitch muscle - answer Fewer mitochondria = anaerobic
metabolism = buildup of lactate = muscle aches
Gluconeogenesis recycles the lactate (first oxidized to pyruvate)
What is the overall reaction of the Cori Cycle - answer 2ATP + 2GTP + 4H2O -->2ADP + 2
GDP + 4P
Liver Pyruvate Kinase - answer -phosphorylation = less active
What are the control points in glycolysis - answer Hexokinase
-inhibited by high levels of Glucose 6 phosphate
Pyruvate Kinase
-inhibited by ATP and alanine
