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Biochemistry-Exam 2 > Gluconeogenesis > Flashcards

Gluconeogenesis Flashcards

0
Q

What two molecules can be made into pyruvate?

A

Alanine and lactate

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1
Q

Where does Gluconeogenesis occur?

A

Liver

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2
Q

Gluconeogenesis: Pyruvate is made into?

A

Oxaloacetate by pyruvate carboxylase

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3
Q

Gluconeogenesis: Oxaloacetate is made into…

A

Phosphoenolpyruvate by phosphoenolpyruvate carboxykinase

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4
Q

Glycerol is fed into the gluconeogensis pathway and…

A

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

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5
Q

In gluconeogenesis, what happens to phosphoenolpyruvate?

A

Made into glyceraldehyde 3 P

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6
Q

Gluconeogenesis: Glyveraldehyde 3 P is made into?

A

Fructose 1,6-bisphosphate

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7
Q

Gluconeogenesis: What happens to Fructose 1,6 bisphosphate?

A

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

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8
Q

Gluconeogensis: What happens to fructose 6-phosphate?

A

Taken to glucose 6-phosphate

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9
Q

Gluconeogenesis: What happens to glucose 6-phosphate?

A

Taken to glucose by glucose 6-phosphatase

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10
Q

How many irreversible steps are there in gluconeogenesis?

A

3

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11
Q

How many ATP equivalents are needed for gluconeogenesis?

A

6 ATP

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12
Q

What three steps in gluconeogenesis are irreversible?

A

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

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13
Q

Lactate is made to pyruvate via?

A

Lactate dehydrogenase and via oxidation of NADH

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14
Q

How is alanine made into pyruvate?

A

Via alanine aminotransferase

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15
Q

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

A

Aerobic has no NADH and anaerobic has NADH available

16
Q

Where is NADH used in gluconeogensis?

A

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

17
Q

Pyruvate to Oxaloacetate requires?

A

CO2, ATP, Biotin, and pyruvate carboxylase

18
Q

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

A

T

19
Q

Describe the aerobic pathway of gluconeogensis to PEP

A

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

20
Q

Describe anaerobic gluconeogenesis to PEP

A

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

21
Q

Where is PEP carboxykinase found?

A

Both in cytosol and in mitochondria

22
Q

In anaerobic PEP formation, where is PEP made?

A

Mitochondria

23
Q

In aerobic gluconeogensis, where is PEP made?

A

Cytosol

24
Q

Which enzyme for gluconeogenesis is primarily found in the liver?

A

Glucose 6-phosphatase

25
Q

What are the 4 bypass enzymes for gluconeogenesis?

A

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

26
Q

PEP carboxylase and pyruvate carboxylase are regulated by?

A

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

27
Q

Fructose 1,6 bisphosphatase is regulated by?

A

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

28
Q

Glucose 6-phosphatase is regulated by?

A

Positive: Fasting

29
Q

In the liver, describe cAMP cascade for glucagon/epinephrine

A

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

30
Q

Glucagon is present in liver

A

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

31
Q

Insulin in the liver…

A

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

32
Q

T or F: Muscle has glucagon receptors

A

F, just epinephrine and insulin

33
Q

Epinephrine in muscle

A

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

34
Q

Insulin in muscle…

A

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

35
Q

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

A

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

36
Q

What is the cori cycle?

A

Reconversion of lactate to glucose by the liver

37
Q

How does the cori cycle work?

A

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

38
Q

Why is drinking alcohol on an empty stomach bad?

A

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

Biochemistry-Exam 2 (14 decks)

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