Gluconeogenesis

Question 1

What is gluconeogeneis

What else can be made

Answer 1

Going from pyruvate to glucose

Other molecules can be made from the the intermediate of this reaction like lactate, amino acids, glycerols

Question 2

Where does gluconeogensis mainly happen

Answer 2

In the liver

Question 3

What are all of the steps of gluconeogenesis

Answer 3

Same as glycolysis just backwards

But after phosphoenol pyruvate, phosphoenol pyruvate carboxy kinase makes oxaloacetate

Oxaloaceetate turns into pyruvate through pyruvate carboxylase

But this is all backwards remember, so oxaloacetate is actuallly formed

Question 4

What reactions in gluconeogensis turn GTP to gdp and atp to adp

Answer 4

Pyruvate to oxaloacetate turns atp to adp

Oxaloacetate to phosphoenol pyruvate turns GTP to gdp

3-phosphoglycerate to 1,3 biphosphoglycerate turns atp to adp

Question 5

Is gluconeogensis the exact reverse of glycolysis

Answer 5

No, the energy used and released to both reactions is not the same

The three irreversible reaction in glycolysis need to be bypassed in gluconeogeneis

Question 6

What are the 3 differences in gluconeogensis compared to glycolysis

Answer 6

Pyruvate to phosphoenol pyruvate occurs in 2 steps instead of one (pyruvate to oxaloacetate then to phosphoenol pyruvate)

Fructose 1 6 bisphosphate to F 6 phosphate uses fructose 1,6 bisphosphatase instead of pfk

G 6 p to glucose uses glucose 6 phosphatase instead of Hexokinase

Question 7

What enzyme turns pyruvate to oxaloacetate, where, and how

Answer 7

Pyruvate carboxylase

This step happens in the mitochondrial matrix

Carboxyl action happens in three steps

Question 8

What is the first step of how pyruvate turns to oxaloacetate

Answer 8

The cofactor bicarbonate (HCO3-) is activated by atp to make carboxyphosphate

Question 9

What is the second step of how pyruvate turns to oxaloacetate

Answer 9

The pyruvate carboxylase enzyme has a biotin conpapent

The previously made carboxyphosphate bind to this part of the enzyme to make the co2-biotin-enzyme

Question 10

What is the third step of how pyruvate turns to oxaloacetate

Answer 10

the newly made co2-biotin-enzyme transfers a CO2 to the pyruvate to form oxaloacetate

The biotin enzyme is reformed to made more oxaloacetate

Question 11

How many domains does pyruvate carboxylase have

Answer 11

4

The three step reaction happens at each domain

Question 12

What enzyme turns oxaloacetate to phosphoenol pyruvate and how

Answer 12

phosphoenol pyruvate carboxy kinase

It hydrolyzes GTP to gdp to decarboxylate oxaloacetate

This make the less stable enol isomer which then gets a phosphate added to it to trap it in that form

Question 13

In the first two steps of gluconeogensis to go from pyruvate to phosphoenol pyruvate, how much atp and GTP is used

Answer 13

1 atp and 1 GTP but it’s hapoens two times so 2 atp and 2 GTP

Question 14

Is something is decarboxylated, what happens after

Answer 14

Phosphorylation
This is a pattern that happens in metabolism

Question 15

Pyruvate turns to oxaloacetate in the

What happens after this and why

Answer 15

Mitochondria

The oxaloacetate gets reduced to malate through the use of NADH (still in mitochondria) and malate degyhydrogenase

This is because the oxaloacetate can’t leave the mitochondria in its current form

Question 16

After malate is formed what happens

Why

Answer 16

It’s moved out of the mitochondria to the cytoplasm

The malate outside the mitochondria then gets oxidized back to oxaloacetate and also makes NADH

The Cytosiloc Nadh is used in gluconeogensis

Question 17

F 16 pisphopahte to F 6 phosphate

G 6p to glucose

How are they different in gluconeogensis

Answer 17

They are important a regulations step and they each have H2O added to form them

Question 18

What does it means that gluconeogensis and glycolysis are regulated reciprocally?

Why

Answer 18

When one process is highly active, the other is inhibited

Because is both happen at the same time, no net atp or GTP is actually being made

Question 19

How is reciprocal regulation done for the pfk in glycolysis and the fructose 1,6 bisphopsphatase in gluconeogensis

Answer 19

In gluconeogensis, the important regulation enzyme is fructose 1,6 bisphosphatase not PFK

It is reciprocal to pfk,

if pfk is activated by amp and F 26 bp, then fructose 1,6 bisphosphatase is inhibited by it.

If there’s low atp (more amp) glycolysis is needed and gluconeogensis is inhibited

If there more glucose, there more F 2 6 bp. If more F 26 bp, more glycolysis and less gluconeogensis

If there’s high citrate (from TCA) or H there’s high energy charge (atp) and pfk if inhibited, so glycolysis is inhibited and gluconeogensis is activated.

Question 20

How is reciprocal regulation done for the pyruvate kinase in glycolysis and the three step reaction to make phosphoenol pyruvate in gluconeogensis

Answer 20

If there’s high adp/amp, energy is needed and gluconeogensis is inhibited (because it uses energy to make glucose)

If there’s high atp and alanine there’s higher energy charge, if there’s more energy pyruvate kinase is inhibited (don’t need to make more energy)

Question 21

What forms the fructose 2,6 bisphopshate that inhibits fructose 1 6 biphosphatase

What forms the fructose 6 phosphate

Answer 21

Phosphofructokinase 2 makes fructose 2,6 bisphopshate

Fructose biphosphatase 2

Question 22

Phosphofructokinase 2, Fructose biphosphatase 2 make up the enzyme fructose 1,6 biphosphatase

What type of enzyme is fructose 1,6 biphosphatase what does this mean

Answer 22

Those two domains exist as a single polypeptide (fructose 1,6 biphosphatase)

It’s a bifunctional enzyme and these two domains is how it’s regulated

When one domain is active, the other is inactive

Question 23

In the state of the fructose 1,6 biphosphatase enzyme where pfk 2 is phosphorylates what happens

Answer 23

If pfk 2 is phosphorylated, it’s inactive.

This makes the fbp 2 active

This means that fructose 2,6 bp is not made, so glycolysis is inhibited and gluconeogensis does happen

Question 24

In the state of the fructose 1,6 biphosphatase enzyme where pfk 2 is dephosphorylated what happens

Answer 24

Pfk 2 is active so the fructose bisphosphatase is inactive

This means that fructose 2 6 bisphosphate is made and glycolysis is stimulated, gluconeogensis is inhibited.

This happens when more glucose

Question 25

How is phosphorylation of the fructose 1,6 biphosphatase enzyme done

Answer 25

It’s phosphorylated when glucose is low so that gluconeogensis happens to make more glucose

Phopshoprotien phosphatase add the phosphate group to the serine residue of pfk 2 domain

Also The glucagon hormone stimulates phosphokinase A to turn on fructose bisphosphatase 2.

This makes fructose 1,6 bisphosphate turn into fructose 6 phosphate and make gluconeogensis happen.

Question 26

High glucose =

Low glucose =

Answer 26

More glycolysis less gluconeogeneis

Opposite

Question 27

Where does gluconeogeneis happen

Answer 27

In the livet

Question 28

How much
Adp
GDP
Nad+
Made in gluconeogensis
What is the delta g

Answer 28

4
2
2
-38

Question 29

How much
Atp
Nadh
Pyruvate
Made in glycolysis
What is the delta g

Answer 29

2
2
2
-90

Question 30

Why is gluconeogensis more energetically favourable

Answer 30

It uses. 6 higher energy bonds to make glucose

(4atp and 2 gtp)