Gluconeogenesis Flashcards
3 main sources for gluconeogesis
Amino acids
Lactate
Glycerol
Where does glycerol go through glucogenogenesis to become glucose?
The liver
What is the major organ for gluconeogenesis?
Liver
What is gluconeogenesis?
Synthesis of glucose from simpler precursors
How much glucose is needed by the body daily?
160g
How much glucose does the brain need per day?
120g
What is exogenous?
Dietary glucose
3 sources of blood glucose
Dietary intake
Glycogenolysis
Gluconeogenesis
When does gluconeogenesis kick in?
At the absence of dietary glucose in the blood
What is missing when the body goes from fasting to starvation?
Glycogen
What is the only fuel for red blood cells?
Glucose
What is the primary fuel for the brain?
Glucose
Does the rate of glycolysis exceed the rate of oxidative metabolism?
Yes
What is the main source of glucose during starvation?
The muscles, when you are starving you body breaks down muscles
Which is the first molecule created in gluconeogenesis?
Pyruvate
What 2 reactions can glycerol be used for?
Glycolysis
Gluconeogenesis
Other than the liver, where does gluconeogenesis take place?
Kidneys (10%)
2 reasons why gluconeogenesis is not the mere reversal of glycolysis
Energetics
Reciprocal regulation
How many irreversible steps in glycolysis must be bypassed in gluconeogenesis?
3
Are gluconeogenesis and glycolysis identical pathways?
No
Where is oxaloacetate formed?
In the mitochondria
What is oxaloacetate reduced to?
Malate
What enzymes uses NADH to reduce oxaloacetate to malate?
Malate dehydrogenase
When is gluconeogenesis predominant over glycolysis?
If glucose is required
When is glycolysis predominant over gluconeogenesis?
If ATP is required
2 molecules that activate glycolysis and inhibits gluconeogenesis?
F-2,6 BP
AMP
What molecule activates gluconeogenesis and inhibits glycolysis?
Citrate
What does ATP inhibit?
PFK-1
How does ATP inhibit PFK-1?
By binding to the allosteric site
What does high concentrations of citrate increase?
The inhibitory effect of ATP
What does high ATP slow?
Glycolysis
What does high ATP speed up?
Gluconeogenesis
Which carbon in glucose is the reducing end?
Carbon 1
What are glycogenic amino acids?
Amino acids which are able to undergo net conversion to glucose
Can mammals convert fatty acids into glucose?
No
Can plants and microorganism convert fatty acids into glucose?
Yes
Where is glyceroneogenesis carried out?
In adipocytes
What is glyceroneogenesis?
Conversion of pyruvate to dihydroxyacetone phosphate
Different sources for glucose
Why are glycolysis and gluconeogenesis reciprocally regulated?
So that they don’t occur simultaneously in a futile cycle
What is it called when glucose is scarce?
Hypoglycemia
What determines whether glycolysis or gluconeogenesis will be most active?
Energy charge
Which will be favored if ATP is required, glycolysis or gluconeogenesis?
Glycolysis
Which will be favored if glucose is required, glycolysis or gluconeogenesis?
Gluconeogenesis
Which hexokinase are inhibited by glucose 6-phosphate?
Hexokinase I
Kexokinase II
Hexokinase III
Which hexokinase is not inhibited by glucose 6-phosphate?
Hexokinase IV
Different name for hexokinase IV
GLucokinase
What inhibits PFK-1?
ATP
What is fructose 2,6-biphosphate a potent allosteric regulator of?
PFK-1 and FBPase-1
What does glucagon signal?
That the liver should produce and release more glucose
What does insulin signal?
That the liver should use glucose as fuel
When is glucagon released?
When blood glucose levels decrease
When is insulin released?
When blood glucose levels increase
What does fructose 2,6-biphosphate stimulate?
Gluconeogenesis
