Week 13 - Unit 3 Flashcards
Substrates for Gluconeogenesis (critical for maintaining blood glucose levels during fasting), include ________, _______, and _______ AA.
Glycerol
Lactate
Gluconeogenic AA
Hormonal regulation (ensure GNG and Glycolysis do not occur at the same time): Gluconeogenesis (GNG) mirrors the reverse of glycolysis except at _____ key steps that are regulated. These enzymes are regulated at the level of _____ and _______ modification.
3
Transcription
Covalent
In integration of GNG and fatty Acid oxidation, GNG is reliant on FA oxidation for both _____ and for _______ that acts to stimulate pyruvate carboxylase. Pathways are tied together.
energy
acetylCoA
GNG will be activated under ______ conditions when _______ levels are high.
Fasting
Glucagon
The pathways for Glycolysis vs. GNG diverge at 3 different locations. The first divergence location for GNG is with the conversion of ______ into ________.
Pyruvate
Phosphophenolpyruvate (PEP)
The enzyme in Glycolysis that converts PEP to Pyruvate is ________ ______ and is irreversible. Therefore in GNG to convert Pyruvate to PEP it uses a series of enzymes including ________ then _________.
Pyruvate Kinase
Pyruvate carboxylase
PEP carboxykinase
The second location that the pathways of Glycolysis and GNG diverge is the conversion of _______ backwards to ________.
Fructose 1,6-Phosphate
Fructose 6-Phosphate
What enzyme will regulate the conversion of Fructose 6-P to Fructose 1,6-P in Glycolysis that is irreversible (GNG cant use the same enzyme)?
Phosphofructokinase -1 (irreversible in Glycolysis )
What enzyme will GNG use to convert Fructose 1,6-P back to Fructose 6-P since it can not use Phosphofructokinase-1(irreversible) ?
Fructose 1,6-Bisphosphatase (removal of phosphate group from Fructose 1,6-P)
What is the third and final step that GNG will diverge from Glycolysis in ?
Conversion of Glucose 6-P back to Glucose
What does glycolysis use to make Glucose into Glucose-6P ? is it irreversible?
Glucokinase (in liver)
Hexokinase (most tissues)
What is the main difference between Glucokinase and Hexokinase?
Glucokinase (in liver- only works at higher glucose concentrations)
Hexokinase (most tissues)
What enzyme will GNG use instead of Gluco/hexokinase to make Glucose 6-P back into Glucose ?
Glucose 6-Phosphatase (only in liver and kidneys, same as one used in Glycogenolysis)
-can move out of cell and into the plasma after phosphate is removed
What are the 4 precursors for GNG ? where are we getting the Carbons to synthesize exogenous Glucose?
Glycerol
Alanine
AA that can funnel into TCA cycle or make Pyruvate
Lactate
In GNG, what will convert Pyruvate into Oxaloacetate (OAA) ?
Pyruvate Carboxylase
In GNG, what will convert OAA into Phosphophenolpyruvate ?
Phosphophenolpyruvate carboxykinase
True or False:
The oxidation of Even chain Fatty Acids (majority of type in body) are not a viable substrate for Gluconeogenesis.
True
The oxidation of Even Chain FA results in the production of what?
Then what oxidizes that product / what is its fate?
Why is this important?
Acetyl CoA
Used up in TCA cycle,
- in its oxidation 2 carbons enter TCA and 2 exit as CO2
- no net Carbons available for GNG
What enzyme will get precursor for GNG lactate converted to pyruvate?
lactate dehydrogenase (reversible) will remove (H+) from Lactate to make Pyruvate
What enzyme will convert Alanine to Pyruvate?
Alanine Aminotransferase
Alanine aminotransferase is ________ and will transfer the amine group(NH3+) to ________ (then turns into glutarate) to then make the _______ that is needed.
reversible
Alpha-keto glutarate
Pyruvate (=O) is where the amine group use to be
What enzyme will convert Glycerol to Glycerol 3-Phosphate in GNG?
Is it reversible?
Glycerol Kinase
not reversible
How do you get the Dihydroxyacetone phosphate needed to combine with Glycerol 3-P to make Fructose 1,6-P ?
Comes from Glycerol that was freed during Lipolysis
2 step reaction- Glycerol Kinase (enzyme) and Glycerol 3-P dehydrogenase (enzyme) used
Is the Glycerol 3-Phosphate Dehydrogenase reversible ? (converts Glycerol 3-P to Dihydroxyacetone Phosphate in GNG)
Yes
-involved NAD+ to NADH+ in GNG to make product needed Dihydroxyacetone phosphate