1.11 Gluconeogenesis Flashcards Preview

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Flashcards in 1.11 Gluconeogenesis Deck (40):
0

Four main precursors for Gluconeogenesis

Lactate
Pyruvate
Glycerol
Most amino acids

1

When does gluconeogenesis occur?

When our blood glucose is depleted

2

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

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

3

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

The liver

4

Cori Cycle involves what two body structures

Muscles
Liver

5

In GNG, What enzyme converts Pyruvate to Oxaloacetate

Pyruvate Carboxylase

6

What is the pathway from Pyruvate to PEP in GNG

Pyruvate --> Oxaloacetate --> PEP

7

What enzyme is used to convert Oxaloacetate to PEP

PEP Carboxykinase

8

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

ATP and HCO3 (carboxyl group to add a carbon)

9

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

GTP

10

What part of GNG occurs in the mitochondria

Pyruvate to Oxaloacetate

11

How does Oxaloacetate leave the mitochondria?

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

12

What is used directly in the malate dehydrogenase enzyme

NAD and NADH

13

High levels of what stimulate the reaction of Pyruvate to Oxaloacetate

Acetyl CoA

14

How is Acetyl CoA concentration regulatory?

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

15

What is the net products of Glunoneogenesis

1 Glucose
2 NAD+
4 ADP
2 GDP

16

What coenzyme is attached to Pyruvate Carboxylase during Gluconeogenesis

Biotin

17

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

The production of NAD+ for Mitochondria
The production of NADH for Cytosol

18

Where is the major site of GNG

Liver but also takes place somewhat in the kidney

19

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

Cytosol, NAD+ --> NADH

20

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

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

21

The conversion of Lactate to Pyruvate yields what?

NADH

22

What enzyme catalyzes Lactate to Pyruvate

Lactate Dehydrogenase

23

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

Fructose 1,6-bisphosphatase

24

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

C1

25

What enzyme catalyzes Glucose 6-Phosphatase to Glucose

Glucose 6 phosphatase

26

Where is G-6-Phosphatase NOT PRESENT?

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

27

Where is Glucose 6-Phosphatase located?

In the membrane of ER

28

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

At the point of the two 3 carbon intermediates of Glycolysis

29

How many high energy phosphate bonds are used during Gluconeogenesis

6 (4x ATP, 2x GTP)

30

Pyruvate Carboxylase is stimulated by what?

Acetyl-CoA

31

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

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

32

Do levels of Acetyl CoA regulate Pyruvate Dehydrogenase

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

33

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

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

34

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

Move reaction towards Fructose 1,6-phosphate

35

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

Move the reaction towards Fructose 6 phosphate

36

In response to starvation the pancreas releases what?

Glucagon

37

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

Drops

38

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

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

39

Glucagon decreases the activity of pyruvate kinase and what happens?

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