Gluconeogenesis

Question 1

The whole body needs _____ grams of glucose per day

Answer 1

160

Question 2

The daily glucose requirement of the brain is ____ grams

Answer 2

120

Question 3

Glucose present in body fluids is ____ grams

Answer 3

20

Question 4

Glucose readily available from glycogen is ____ grams

Answer 4

190

Question 5

How long can you go without ingesting glucose to where your glucose reserves can compensate?

Answer 5

One day

Question 6

_______ is especially important for during longer periods of fasting or starvation

Answer 6

Gluconeogenesis

Question 7

What organs does gluconeogenesis occur?

Answer 7

Liver and Kidneys

Question 8

What is Gluconeogenesis?

Answer 8

Synthesis of glucose from non-carbohydrate precursors

Question 9

Is gluconeogenesis a reversal of glycolysis?

Answer 9

No, because different enzymes catalyze the reactions and oxaloacetate is used in gluconeogenesis whereas it is not found in glycolysis

Question 10

What is the overall process of gluconeogenesis? (first and last molecule)

Answer 10

Pyruvate into glucose

Question 11

What are the 3 major precursors of gluconeogenesis?

Answer 11

Lactate
Amino acids
Glycerol

Question 12

Gluconeogenesis _____ the irreversible steps of glycolysis

Answer 12

Bypasses

Question 13

How does gluconeogenesis bypass the irreversible steps of glycolysis?

Answer 13

Through the 4 enzymes not present in glycolysis:

Pyruvate Carboxylase
Phosphoenolpyruvate Carboxykinase
Fructose 1,6-Bisphosphatase
Glucose 6-Phosphatase

Question 14

Where does gluconeogenesis first occur?

Answer 14

In the mitochondria

Question 15

How does gluconeogenesis transition from beginning in the mitochondria to the cytoplasm

Answer 15

Pyruvate is in the mitochondria and converts to oxaloacetate, which converts to Malate. This can leave the mitochondria via the Malate Shuttle and re-convert back to oxaloacetate in the cytoplasm

Question 16

List the steps of gluconeogenesis

Answer 16

Pyruvate is converted into oxaloacetate by pyruvate kinase

OAA is converted into phosphoenolpyruvate by phosphoenolpyruvate carboxykinase

phosphoenolpyruvate is converted to 2-Phosphoglycerate by enolase

2-Phosphoglycerate is converted into 3-Phosphoglycerate by phosphoglycerate mutase

3-Phosphoglycerate is converted into 1,3-Bisphosphoglycerate by Phosphoglycerate kinase

1,3-Bisphosphoglycerate is converted into Glyceraldehyde 3-phosphate by G3P dehydrogenase

G3P converts to Fructose 1,6-bisphosphate by Aldolase

Fructose 1,6-bisphosphate converts to Fructose 6 phosphate by Fructose 1,6 bisphosphatase

Fructose 6 phosphate converts to Glucose 6 phosphate by phosphoglucokinase

G6P is converted into Glucose by Glucose 6 phosphatase

Question 17

Where is Glucose 6 phosphate located?

Answer 17

in the lumen of the ER

Question 18

What 3 proteins are used to shuttle glucose/G6P and what does each specifically do?

Answer 18

T1- transports Glucose-6-Phosphate to ER
T2-transports inorganic phosphate back
T3-transports free Glucose back to the cytoplasm

Question 19

Glycolysis ____ ATP, Gluconeogenesis ____ ATP

Answer 19

Generates

Consumes

Question 20

Gluconeogenesis and Glycolysis are ______ ______

Answer 20

reciprocally regulated

Question 21

When is glycolysis favored?

Answer 21

When blood [insulin] is high

Question 22

When is gluconeogenesis favored?

Answer 22

When blood [glucose] levels are low and glycogen stores are depleted

Question 23

Where does glycolysis occur? Tissue and subcellular

Answer 23

RBCs, exercising muscles, brain, cytosol

Question 24

Where does gluconeogenesis occur? Tissue and subcellular

Answer 24

Liver (mostly), kidneys, and small intestines

Subcellular: mitochondria and cytosol

Question 25

What are the positive regulators of glycolysis?

Answer 25

``` Glucose Insulin AMP Fructose 2,6-Bisphosphate Fructose 1,6 Bisphosphate ```

Question 26

What are the positive regulators of gluconeogenesis?

Answer 26

``` Glucagon Citrate Cortisol Thyroxine Acetyl CoA ```

Question 27

What are the negative regulators of glycolysis?

Answer 27

``` Glucagon ATP Citrate G6P Fructose 6 Phosphate Alanine ```

Question 28

What are the negative regulators of gluconeogenesis?

Answer 28

ADP AMP Fructose 2,6-bisphosphate

Question 29

Describe the energy usage and yield of glycolysis

Answer 29

Use: 2 ATP Yield: 4 ATP Net Yield: 2 ATP/glucose oxidized

Question 30

Describe the energy usage and yield of gluconeogenesis

Answer 30

Use: 4 ATP, 2 GTP Yield: 0 Net Yield: 6 ATP Equivalents/glucose oxidized

Question 31

In the ______, rates of glycolysis and gluconeogenesis are adjusted to maintain blood glucose

Answer 31

Liver

Question 32

_______ strongly stimulates Phosphofructokinase and inhibits Fructose 1,6- bisphosphatase

Answer 32

Fructose 2,6-bisphosphate

Question 33

What 2 enzymes regulate the conc. of Fructose 2,6- bisphosphate

Answer 33

``` Phosphofructokinase 2 (PFK2) Fructose Bisphosphatase 2 (FBPase2) ```

Question 34

What is the Corri Cycle?

Answer 34

Lactate produced in skeletal muscle and RBCs can be converted back to pyruvate in the liver The pyruvate can enter the gluconeogenesis pathway and regenerate glucose (which is the source of lactate)

Question 35

What is generated by the action of pyruvate carboxylase?

Answer 35

Oxaloacetate

Question 36

What enzyme is the gluconeogenesis partner of phosphofructokinase?

Answer 36

Fructose 1,6 bisphosphatase

Question 37

What is the most important substrate of the Corri Cycle?

Answer 37

Lactate