Gluconeogenesis and Related Reactions
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62 Terms
What is the first gluconeogenesis bypass?
Conversion of pyruvate → oxaloacetate → PEP
What enzyme is required for step one of bypass 1?
Pyruvate Carboxylase (biotinated)
Enzyme that converts Pyruvate → Oxaloacetate
Pyruvate Carboxylase (biotinated)
What additional reactants are needed for step one of bypass 1?
Co2, ATP, and biotin
What enzyme is required for the second step of bypass 1?
PEP Carboxykinase
Enzyme that converts Oxaloacetate → PEP
PEP Carboxykinase
True or false: Biotin is required for step two of bypass 1.
False
Where does step one of bypass 1 occur?
The mitochondria
Where does step two of bypass 1 occur?
The cytosol and mitochondria
What additional molecules are needed for step two of bypass 1?
GTP
How many high energy phosphates are needed to turn one pyruvate molecule back into PEP?
2
How many high energy phosphates are needed for the entire gluconeogenesis pathway?
6
What is the second gluconeogenesis Bypass?
Conversion of F-1,6-BP → F-6-P
What is the enzyme required for bypass 2?
Fructose-1,6-Bisphosphatase (F-1,6-BPase)
Where does Bypass 2 occur?
the cytosol
What is the third bypass of gluconeogenesis?
Conversion of G-6-P → Glucose
What is the enzyme for bypass 3?
Glucose-6-Phosphatase
Where does bypass 3 occur?
The ER
What enzyme(s) is/are required for glycogen degradation?
Glycogen Phosphorylase and Debranching Enzyme
What enzyme(s) is/are required for glycogen degradation?
Glycogen Phosphorylase and Debranching Enzyme
What is the rate limiting enzyme in glycogen breakdown?
Glycogen Phosphorylase
What happens when Glycogen phosphorylase is phosphorylated?
It is activated
What happens when glycogen phosphorylase is de-phosphorylated?
It is inactivated
What happens when Glycogen Phosphorylase is in a low energy environment?
It is activated
What happens when glycogen phosphorylase is in a high energy environment?
It is inactivated
What happens when glycogen synthase is phosphorylated?
It is inactivated
What happens when glycogen synthase is de-phosphorylated?
It is activated
What effect does glucagon and epinephrine have on glycogen degredation?
It activates degradation
What effect does glucagon and epinephrine have on glycogen synthesis?
It inhibits synthesis
What effect does insulin have on glycogen synthesis?
It activates glycogen synthesis
Glycogen Synthase Kinase 3 (GSK3)
inhibits glycogen synthesis
What happens when GSK3 is phosphorylated?
It is inhibited
What happens when GSK3 is de-phosphorylated?
It is activated
What happens to glycogen synthesis when GSK3 is phosphorylated?
It is stimulated
What effect does an increase in ATP have on glycolysis?
It inhibits it
What effect does an increase in ATP have on gluconeogensis?
It activates it
What effect does an increase in AMP have on glycolysis?
It activates it
What effect does an increase in AMP have on gluconeogenesis?
It inhibits it
What effect does an increase in insulin have on glycolysis?
It activates it
What effect does an increase in insulin have on gluconeogenesis?
It inhibits it
What effect does an increase in acetyl-CoA have on glycolysis?
It inhibits it
What effect does an increase in acetyl-CoA have on gluconeogenesis?
It activates it
What effect does an increase in F-2,6-BP have on glycolysis?
It activates it
What effect does an increase in F-2,6-BP have on gluconeogenesis?
It inhibits it
What effect does an increase in F-1,6-BP have on glycolysis?
It activates it
What effect does an increase in F-1,6-BP have on gluconeogenesis?
It inhibits it
What effect does an increase in G-6-P have on glycolysis?
It inhibits it
What effect does an increase in G-6-P have on gluconeogenesis?
It activates it
What effect does an increase in citrate have on glycolysis?
It inhibits it
What effect does an increase in citrate have on gluconeogenesis?
It activates it
Phosphofructokinase 2 (PFK2)
F-6-P → F-2,6-BP
What effect does PFK2 have on glycolysis?
It activates it
What effect does PFK2 have on gluconeogenesis?
It inhibits it
Fructose-2,6-Bisphosphatase (F-2,6-BPase)
F-2,6-BP → F-6-P
What happens when PFK2 is phosphorylated?
It is inhibited
What happens when PFK2 is de-phosphorylated?
It is activated
What happens when F-2,6-BPase is phosphorylated?
It is activated
Protein Kinase (PKA)
phosphorylates PFK-2 and F-2,6-BPase in response to G-protein signaling caused by increased glucagon levels
Cori Cycle
converts lactate to glucose
Glycerol Kinase
Glycerol → Glycerol-3-Phosphate
Glycerol-3-Phosphate Dehydrogenase
Glycerol-3-Phosphate → DHAP
What are the mechanisms of metabolic control?
Allosteric regulation, covalent modification, substrate cycling, and genetic control
Note 
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