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44 Cards in this Set

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  • Back
In gluconeogenesis, the 7 reversed steps of glycolysis have physiological ΔG at what value?
Near zero
In gluconeogenesis, the 3 non-reversed steps of glycolysis have physiological ΔG at what value?
Less than zero, thus exergonic.
What are the only two amino acids that can not feed into gluconeogenesis?
leucine and lysine
Gluconeogenic, TCA intermediates get funneled through which molecule?
In gluconeogenesis, hexokinase is circumvented by what enzyme?
glucose 6 phosphatase
In gluconeogenesis, PFK1 is circumvented by what enzyme?
Fructose 1,6-bisphosphate (FBP-1)
In gluconeogenesis, pyruvate kinase is circumvented by what enzyme?
1.) Pyruvate carboxylase
2.) Phosphoenolpyruvate Carboxykinase (PEPCK)
How does Acetyl CoA drive pyruvate?
1.) It can drive towards gluconeogenesis by activating pyruvate carboxylase (thus converting pyrvate to oxaloacetate).
2.) It can inhibit drive towards TCA by inhibiting Pyruvate Dehydrogenase Complex
In the first bypass stage of gluconeogenesis, what must be formed and from what? Also include the intermediate.
PEP must be formed from Pyruvate via oxaloacetate.
How does oxaloacetate leave the mitochondria? 3 steps
1.) Must first oxaloacetate must be converted to malate.
2.) Then go through the malate shuffle.
3.) Then reoxidized to oxaloacetate.
In order for pyruvate to convert to oxaloacetate, what other players must be present? X 4
1.) ATP (hydrolyzed to ADP)
2.) Bicarbonate
3.) Biotin
4.) Pyruvate Carboxylase
What activates pyruvate?
The addition of CO2
What two major events occur in the converting of oxaloacetate to PEP?
1.) Decarboxylation (loss of CO2)
2.) Phosphorylation
What are the players needed to convert oxaloacetate to PEP?
2.) GTP (phosphorylates)
The two consecutive reactions to convert pyruvate to PEP (via oxaloacetate) are what kind of reactions in terms of energy?
What is the strategic purpose of transferring oxaloacetate from the mitochondria to the cytosol via malate shuttle?
To maintain reducing equivalents (NADH) in the cytosol
Describe the short route to PEP.
The liver specializes in the short route with enzymes already in the mitochondria, thus creating PEP in the MITO.
Why does alcohol consumption for undernourished or after strenuous exercise cause low blood glucose levels (hypoglycemia)?
Alcohol in the blood will become oxidized by NAD (which will become reduced to NADH). NADH in large cytosol quantities, in the presence of oxaloacetate (or pyruvate) will convert to malate (or lactate). This means that oxaloacetate and pyruvate will be unable to support gluconeogenesis
What is the enzyme associated with the second bypass in gluconeogenesis?
Fructose bisphosphatase (FBP-1)
What are the regulators for FBP-1?
AMP and F2,6P
What are the two major regulatory activities of F2,6P?
1.) Allosterically activates PFK-1
2.) Inhibits FBPase-1
How does F2,6P regulate?
What regulates F2,6P?
1.) PFK-2 (with ATP) increases levels
2.) FBP-2 decreases levels
Glucose 6 Phosphatase is not found where?
Brain and muscle (thus gluconeogenesis does not occur here)
Describe the actions G6Pase in gluconeogenesis.
Releases phosphate group liberating free glucose
What is the physiological ΔG for glycolysis? Is this reaction favorable?
-63 kJ/mol. Favorable
What is the physiological ΔG for gluconeogenesis? Is this reaction favorable?
-16 kJ/mol. Favorable
Increase of Insulin/Glucagon ration does what?
Decreases cAMP and Protein Kinase A levels
Decreased levels of cAMP and Protein Kinase A favors what state and activity?
The dephosphorylated state of PFK-2/FBP-2 complex, meaning that PFK-2 is active and FBP-2 is inactive.
The active PFK-2 means increased creation of what?
Creation of F2,6P
Increased creation of F2,6P means what?
Increased activity of PFK-1 leading to drive towards glycolysis.
Decrease of Insulin/Glucagon ration leads to what?
Increase of cAMP and Protein Kinase A levels.
Increased cAMP and Protein Kinase A leads to what?
Leads to phosphorylated state of PFK-2/FBP-2 complex.
What does the phosphorylated PFK-2/FBP-2 mean?
Active FBP-2, and inactive PFK-2
Active FBP-2 means what?
Decreases the amount of F2,6P
Decreasing the amount of F2,6P leads to what?
DErepressing the FBPase-1, thus promoting gluconeogenesis.
PFK-2/FBP-2 is what type of protein?
A single bifunctional protein
What are the long term effects of glucagon genetically
Represses the genes encoding the three regulatory enzymes of glycolysis IN THE LIVER
How much energy is required to convert 2 lactate molecules to 1 glucose molecule?
How much is required to convert glucose to lactate?
T/F - The brain does not fully oxidize glucose thus it will funnel back lactate.
FALSE. It fully oxidizes the glucose
What does the Cori Cycle shuttle and to where?
Glucose and lactate between the liver and muscle/RBC
Describe the Alanine cycle.
Alanine is transanimated to become pyruvate which will go through gluconeogenesis to become glucose.
How much glucse is needed by the brain, muscle, and RBC's a day?
120 g