Gluconeogenesis

Question 0

What two molecules can be made into pyruvate?

Answer 0

Alanine and lactate

Question 1

Where does Gluconeogenesis occur?

Answer 1

Liver

Question 2

Gluconeogenesis: Pyruvate is made into?

Answer 2

Oxaloacetate by pyruvate carboxylase

Question 3

Gluconeogenesis: Oxaloacetate is made into…

Answer 3

Phosphoenolpyruvate by phosphoenolpyruvate carboxykinase

Question 4

Glycerol is fed into the gluconeogensis pathway and…

Answer 4

Phosphorylated to glycerol-3-P and into Dihydroxyacetone-P and fed into Fructose 1,6-bisphosphate

Question 5

In gluconeogenesis, what happens to phosphoenolpyruvate?

Answer 5

Made into glyceraldehyde 3 P

Question 6

Gluconeogenesis: Glyveraldehyde 3 P is made into?

Answer 6

Fructose 1,6-bisphosphate

Question 7

Gluconeogenesis: What happens to Fructose 1,6 bisphosphate?

Answer 7

Taken to Fructose 6-phosphate via fructose 1,6-bisphosphatase

Question 8

Gluconeogensis: What happens to fructose 6-phosphate?

Answer 8

Taken to glucose 6-phosphate

Question 9

Gluconeogenesis: What happens to glucose 6-phosphate?

Answer 9

Taken to glucose by glucose 6-phosphatase

Question 10

How many irreversible steps are there in gluconeogenesis?

Answer 10

3

Question 11

How many ATP equivalents are needed for gluconeogenesis?

Answer 11

6 ATP

Question 12

What three steps in gluconeogenesis are irreversible?

Answer 12

Pyruvate to oxaloacetate (2 ATP via pyruvate carboxylase), Oxaloacetate to Phosphoenolpyruvate (PEP carboxykinase, 2 GTP) and Glucose 6-P to glucose (glucose 6-phosphatase)

Question 13

Lactate is made to pyruvate via?

Answer 13

Lactate dehydrogenase and via oxidation of NADH

Question 14

How is alanine made into pyruvate?

Answer 14

Via alanine aminotransferase

Question 15

What is the difference between gluconeogensis in aerobic and anaerobic conditions?

Answer 15

Aerobic has no NADH and anaerobic has NADH available

Question 16

Where is NADH used in gluconeogensis?

Answer 16

2 NADH to 2 NAD in 2 1,3-bisphophate to Glyceraldehyde 3-P

Question 17

Pyruvate to Oxaloacetate requires?

Answer 17

CO2, ATP, Biotin, and pyruvate carboxylase

Question 18

Gluconeogenesis: T or F: Pyruvate carboxylase happens exclusively in the mitochondria

Answer 18

T

Question 19

Describe the aerobic pathway of gluconeogensis to PEP

Answer 19

Pyruvate into mitochondria, Pyruvate to Oxaloacetate, Oxaloacetate to Malate with 1 NADH to NAD, Malate out of mitochondria, malate to oxaloacetate via cystolic malate dehydrogenase, then cystolic PEP carboxykinase to PEP

Question 20

Describe anaerobic gluconeogenesis to PEP

Answer 20

Lactate to Pyruvate vis lactate dehydrogenase producing NADH, Pyruvate into mitochondria, Pyruvate to Oxaloacetae via pyruvate carboxylase, then mitochondrial PEP carboxykinase to PEP, PEP out

Question 21

Where is PEP carboxykinase found?

Answer 21

Both in cytosol and in mitochondria

Question 22

In anaerobic PEP formation, where is PEP made?

Answer 22

Mitochondria

Question 23

In aerobic gluconeogensis, where is PEP made?

Answer 23

Cytosol

Question 24

Which enzyme for gluconeogenesis is primarily found in the liver?

Answer 24

Glucose 6-phosphatase

Question 25

What are the 4 bypass enzymes for gluconeogenesis?

Answer 25

Pyruvate carboxylase (driven by acetyl CoA), PEP carboxylase, Fructose 1,6 bisphosphatase, and glucose 6-phosphatase

Question 26

PEP carboxylase and pyruvate carboxylase are regulated by?

Answer 26

Positive: Acetyl CoA, glucagon, epinephrine, glucocorticoids Negative: Insulin

Question 27

Fructose 1,6 bisphosphatase is regulated by?

Answer 27

Positive: during fasting Negative: F-2,6-P, AMP

Question 28

Glucose 6-phosphatase is regulated by?

Answer 28

Positive: Fasting

Question 29

In the liver, describe cAMP cascade for glucagon/epinephrine

Answer 29

cAMP activates PKA which phosphorylates PFK-2 to the inactive mode activating FBP-2 of the bienzyme. This decreases Fructose 2,6 bisphophate which stops inhibition of fructose bisphosphatase 1 allowing Fructose 6-phosphate to be made

Question 30

Glucagon is present in liver

Answer 30

cAMP activated = P of PFK2/FBP 2 = decreased F2,6BP = decreased glycolysis/increased gluconeogensis

Question 31

Insulin in the liver...

Answer 31

cAMP deactivated = dP of PFK 2/FBP2 = increased F2,6BP = increased glycolysis/decreased gluconeogenesis

Question 32

T or F: Muscle has glucagon receptors

Answer 32

F, just epinephrine and insulin

Question 33

Epinephrine in muscle

Answer 33

cAMP activated = P of PFK2/FBP2 = activates production of F2,6BP = increases glycolysis!!

Question 34

Insulin in muscle...

Answer 34

cAMP turned off, dP of PFK2, decreases F2,6BP which decreases glycolysis

Question 35

Why is the effect of P in the PFK2/FBP2 enzymes different in muscle/liver?

Answer 35

Different isozymes. P in muscle activates PFK2, P in liver deactivates PFK2

Question 36

What is the cori cycle?

Answer 36

Reconversion of lactate to glucose by the liver

Question 37

How does the cori cycle work?

Answer 37

Lactate in blood taken up by liver and undergoes gluconeogensis and glucose is sent to RBC where it undergoes glycolysis to make more lactate

Question 38

Why is drinking alcohol on an empty stomach bad?

Answer 38

Ethanol makes a lot of NADH which then makes lots of malate and lactate which prevents Gluconeogensis starving brain of glucose