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Metabolism > 1.11 Gluconeogenesis > Flashcards

1.11 Gluconeogenesis Flashcards

0
Q

When does gluconeogenesis occur?

A

When our blood glucose is depleted

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1
Q

Four main precursors for Gluconeogenesis

A

Lactate
Pyruvate
Glycerol
Most amino acids

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2
Q

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

A

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

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3
Q

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

A

The liver

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4
Q

Cori Cycle involves what two body structures

A

Muscles

Liver

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5
Q

In GNG, What enzyme converts Pyruvate to Oxaloacetate

A

Pyruvate Carboxylase

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6
Q

What is the pathway from Pyruvate to PEP in GNG

A

Pyruvate –> Oxaloacetate –> PEP

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7
Q

What enzyme is used to convert Oxaloacetate to PEP

A

PEP Carboxykinase

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8
Q

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

A

ATP and HCO3 (carboxyl group to add a carbon)

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9
Q

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

A

GTP

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10
Q

What part of GNG occurs in the mitochondria

A

Pyruvate to Oxaloacetate

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11
Q

How does Oxaloacetate leave the mitochondria?

A

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

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12
Q

What is used directly in the malate dehydrogenase enzyme

A

NAD and NADH

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13
Q

High levels of what stimulate the reaction of Pyruvate to Oxaloacetate

A

Acetyl CoA

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14
Q

How is Acetyl CoA concentration regulatory?

A

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

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15
Q

What is the net products of Glunoneogenesis

A

1 Glucose
2 NAD+
4 ADP
2 GDP

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16
Q

What coenzyme is attached to Pyruvate Carboxylase during Gluconeogenesis

A

Biotin

17
Q

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

A

The production of NAD+ for Mitochondria

The production of NADH for Cytosol

18
Q

Where is the major site of GNG

A

Liver but also takes place somewhat in the kidney

19
Q

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

A

Cytosol, NAD+ –> NADH

20
Q

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

A

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

21
Q

The conversion of Lactate to Pyruvate yields what?

A

NADH

22
Q

What enzyme catalyzes Lactate to Pyruvate

A

Lactate Dehydrogenase

23
Q

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

A

Fructose 1,6-bisphosphatase

24
Q

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

A

C1

25
Q

What enzyme catalyzes Glucose 6-Phosphatase to Glucose

A

Glucose 6 phosphatase

26
Q

Where is G-6-Phosphatase NOT PRESENT?

A

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

27
Q

Where is Glucose 6-Phosphatase located?

A

In the membrane of ER

28
Q

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

A

At the point of the two 3 carbon intermediates of Glycolysis

29
Q

How many high energy phosphate bonds are used during Gluconeogenesis

A

6 (4x ATP, 2x GTP)

30
Q

Pyruvate Carboxylase is stimulated by what?

A

Acetyl-CoA

31
Q

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

A

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

32
Q

Do levels of Acetyl CoA regulate Pyruvate Dehydrogenase

A

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

33
Q

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

A

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

34
Q

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

A

Move reaction towards Fructose 1,6-phosphate

35
Q

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

A

Move the reaction towards Fructose 6 phosphate

36
Q

In response to starvation the pancreas releases what?

A

Glucagon

37
Q

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

A

Drops

38
Q

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

A

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

39
Q

Glucagon decreases the activity of pyruvate kinase and what happens?

A

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

Metabolism (31 decks)

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