GLuconeogenesis

Question 1

4 important enzymes to know details about regarding gluconeogenesis

Answer 1

1. Glucose 6 phosphate (ER)
2. Fructose 1,6 -Bisphosphatase (cytosol)
3. PEPCK (Cytosol)
4. Pyruvate Carboxylase (Mitochondrial matrix)

Question 2

Pyruvate carboxylase regulation

Answer 2

catalyzes the carboxylation of pyruvate to make oxallo acetate.

Question 3

Pyruvate carboxylase is located ? and requires?

Answer 3

mito matrix
biotin

run driven by ATP hydrolysis

Question 4

PEPCK does what

Answer 4

turns OAA into PEP (driven by GTP hydrolysis )

Question 5

Fructose 1,6, Bis Pase does what?

Answer 5

Turns Fructose 1,6,-Bisphosphatase into Fructose 6 phosphate

Question 6

G6Pase does what ?

Answer 6

G6P into glucose

Question 7

B oxidation provides what

Answer 7

ATP and NADH

Question 8

Pyruvate carboxylase is allosterically activated by what?

Answer 8

Ace-COA increases with fasting (B-ox) so it says “make more glucose”

Question 9

Phosphoenolpyruvate Carboxykinase regulation

Answer 9

regulated by gene expression

–activated by epi, cortisol, which activate PKA which activated PEPCK

Question 10

Fructose 1,6, Bis phosphatase is inhibited and activated by ?

Answer 10

A : ATP and citate

I: AMP and F 2,6, BP

Question 11

How are the levels of Fructose 2,6-Bisphosphate regulated?

Answer 11

By 2 enzymes of the same polypeptide (FBPase2 and PFK2) . When the bifunctional protein is phosphorylated then PBPase2 dominates and lowers the levels of Fructose 2,6,-BisP and raising levels of Fructose 6,P. Which activates the gluconeogenic pathway. What phosphorylates the bifunctional protein ? PKA does ..

Follow this ,, Fasting ups PKA which leads to phosphorylation of the bifunctional protein. Then you increase the activity of the FBPase enzyme and lower the levels of F-2,6, BP. This allows fructose 1,6 bisphosphatatase to be more active. At the same time , this will decrease the activity of the glycolytic enzyme .

The reverse is also true .. when the bifunctional protein is not phosphorylated , then the PFK2 enzyme dominates leading to an increase in Fructose 2,6-BisP. and a decrease in Fructose -6,P. With an increase F-2,6-BisP, this inhibits the activity of the gluconeogenic pathway and activates the glycolytic pathway.

So, when we are not fasting, (high blood glucose) then PKA will be low. The bifunctional protein will not be phosphorylated. That is why the PFK2 enzyme dominates thus leading to increased F-2,6, Bis P. which increases the glycolytic pathway.

Question 12

Regulation of G6Pase.

Answer 12

Regulated at gene expression. Induced expression by glucagon, epi, and cortisol. These all activate PKA which activates Glucose 6-phosphatase.

Question 13

General rule of PKA regulation relating to gluconeogenic and glycolytic pathway

Answer 13

up regulate glujconeogeneis and down regulate glycolysis.

Question 14

Drinking on an empty stomach ..

Answer 14

depletes the body of NAD+ and gives it too much NADH

Question 15

Von Gierke’s Disease

Answer 15

Defect in glucose 6-phosphatase.

can’t rid of liver glycogen.

Defects in carriers transporting G6P, glucose , or Pi across the ER membrane have similar phenotypes.

Question 16

Glucose 6-phosphate and how it regulated glycogen synthesis.

Answer 16

increases glycogen synthesis and decreases glycogen breakdown.