1.11 Gluconeogenesis

Question 0

When does gluconeogenesis occur?

Answer 0

When our blood glucose is depleted

Question 1

Four main precursors for Gluconeogenesis

Answer 1

Lactate
Pyruvate
Glycerol
Most amino acids

Question 2

Which three steps of Glycolysis are not reversable steps in GNG?

Answer 2

Glucose to G-6-P
F-6-P to F-1,6-P
PEP to Pyruvate

Question 3

Lactate is made to Glucose during the Cori Cycle in what body structure?

Answer 3

The liver

Question 4

Cori Cycle involves what two body structures

Answer 4

Muscles

Liver

Question 5

In GNG, What enzyme converts Pyruvate to Oxaloacetate

Answer 5

Pyruvate Carboxylase

Question 6

What is the pathway from Pyruvate to PEP in GNG

Answer 6

Pyruvate –> Oxaloacetate –> PEP

Question 7

What enzyme is used to convert Oxaloacetate to PEP

Answer 7

PEP Carboxykinase

Question 8

What substrates are needed to convert Pyruvate to Oxaloacetate other than the enzyme?

Answer 8

ATP and HCO3 (carboxyl group to add a carbon)

Question 9

What other substrates are involved in converting oxaloacetate to PEP other than its enzyme

Answer 9

GTP

Question 10

What part of GNG occurs in the mitochondria

Answer 10

Pyruvate to Oxaloacetate

Question 11

How does Oxaloacetate leave the mitochondria?

Answer 11

It is converted to Malate and transported across the mitochondrial membrane. In the cytosol it is converted back to Oxaloacetate.

Question 12

What is used directly in the malate dehydrogenase enzyme

Answer 12

NAD and NADH

Question 13

High levels of what stimulate the reaction of Pyruvate to Oxaloacetate

Answer 13

Acetyl CoA

Question 14

How is Acetyl CoA concentration regulatory?

Answer 14

Depending on Acetyl CoA concentration, Pyruvate will either proceed to Acetyl CoA or reverse to Oxaloacetate and PEP by GNG

Question 15

What is the net products of Glunoneogenesis

Answer 15

1 Glucose
2 NAD+
4 ADP
2 GDP

Question 16

What coenzyme is attached to Pyruvate Carboxylase during Gluconeogenesis

Answer 16

Biotin

Question 17

Why is the transport of Oxaloacetate by Malate Dehydrogenase considered a Circuitous?

Answer 17

The production of NAD+ for Mitochondria

The production of NADH for Cytosol

Question 18

Where is the major site of GNG

Answer 18

Liver but also takes place somewhat in the kidney

Question 19

Is NADH produced in the mitochondrial matrix or in the cytosol during the malate dehydrogenase

Answer 19

Cytosol, NAD+ –> NADH

Question 20

At what point does CO2 leave during the conversion of Pyruvate to PEP

Answer 20

CO2 leaves during the conversion of Oxaloacetate to PEP by PEP Carboxykinase

Question 21

The conversion of Lactate to Pyruvate yields what?

Answer 21

NADH

Question 22

What enzyme catalyzes Lactate to Pyruvate

Answer 22

Lactate Dehydrogenase

Question 23

What enzyme catalyzes the GNG reaction of F 1,6-P to F 6-P

Answer 23

Fructose 1,6-bisphosphatase

Question 24

F 6-P is formed by hydrolysis of the phosphate group at what Carbon

Answer 24

C1

Question 25

What enzyme catalyzes Glucose 6-Phosphatase to Glucose

Answer 25

Glucose 6 phosphatase

Question 26

Where is G-6-Phosphatase NOT PRESENT?

Answer 26

In the Brain and muscle it is not present so glucose cannot be formed by these organs

Question 27

Where is Glucose 6-Phosphatase located?

Answer 27

In the membrane of ER

Question 28

Where does Glycerol enter the Gluconeogenesis cycle to be used as a precursor to Glucose

Answer 28

At the point of the two 3 carbon intermediates of Glycolysis

Question 29

How many high energy phosphate bonds are used during Gluconeogenesis

Answer 29

6 (4x ATP, 2x GTP)

Question 30

Pyruvate Carboxylase is stimulated by what?

Answer 30

Acetyl-CoA

Question 31

Describe the process when the energy needs of the cell have been met?

Answer 31

NADH accumulates which inhibits the citric acid cycle and levels of Acetyl CoA go up

Question 32

Do levels of Acetyl CoA regulate Pyruvate Dehydrogenase

Answer 32

Yes, High levels of Acetyl CoA inhibit Pyruvate dehydrogenase and activate Pyruvate Carboxylase

Question 33

When does the reaction move towards Fructose 1,6-phosphatase

Answer 33

When Low Energy charge are present OR High concentration of Fructose 2,6 bisphosphate

Question 34

Elevated levels of AMP and depressed levels of citrate and ATP do what?

Answer 34

Move reaction towards Fructose 1,6-phosphate

Question 35

High energy charge and low concentration of Fructose 2,6 bisphosphate do what?

Answer 35

Move the reaction towards Fructose 6 phosphate

Question 36

In response to starvation the pancreas releases what?

Answer 36

Glucagon

Question 37

When glucagon is released, the level of Fructose 2,6 bisphosphate does what?

Answer 37

Drops

Question 38

The decreased levels of Fructose 2,6 bisphosphate causes what?

Answer 38

decreased activity of PFK1 and increases activity of Fructose 1,6-phosphatase

Question 39

Glucagon decreases the activity of pyruvate kinase and what happens?

Answer 39

PEP accumulates and induces more glycogen breakdown to release more glucose in bloodstream