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Biochem > Gluconeogenesis > Flashcards

Gluconeogenesis Flashcards

1
Q

Gluconeogensis primarily occurs in this type of cell

A

Liver

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2
Q

Cellular location of gluconeogenesis

A

Cytosolic and mitochondrial

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3
Q

Pyruvate can be transaminated in the muscle to form this

A

Alanine

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4
Q

Only amino acids that are not glucogenic

A

Leucine and lysine

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5
Q

Describes how some amino acids can generate pyruvate or citric acid cycle intermediates

A

Glucogenic

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6
Q

Enzyme that catalyzes:
Glycerol + ATP –> glycerol-3-phosphate + ADP

A

Glycerol kinase

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7
Q

Enzyme that catalyzes:
Glycerol-3-phosphate + NAD+ –> Dihydroxyacetone phosphate + NADH

A

Glycerol-3-phosphate dehydrogenase

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8
Q

Enzyme that catalyzes:
Pyruvate –> oxaloacetate

A

Pyruvate carboxylase

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9
Q

First step in gluconeogenesis

A

Pyruvate carboxylase

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10
Q

Allosteric activation of pyruvate carboxylase

A

Acetyl CoA

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11
Q

Requirements of pyruvate carboxylase (2)

A

Biotin and ATP

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12
Q

Pyruvate carboxylase is inhibited by

A

Avidin

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13
Q

Avidin binds to this

A

Biotin

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14
Q

Cellular location of pyruvate carboxylase

A

Mitochondria

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15
Q

Two ways for transport of oxaloacetate out of the mitochondria

A

Malate shuttle or aspartate shuttle

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16
Q

Enzyme that catalyzes:
Oxaloacetate + GTP –> phosphoenolpyruvate + GDP

A

Phosphoenolpyruvate carboxykinase (PEPCK)

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17
Q

Cellular location of PEPCK

A

1/2 mitochondrial and 1/2 cytosol

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18
Q

Regulation of PEPCK

A

Transcriptional regulation
Glucagon increases [PEPCK]
Insulin decreases [PEPCK]

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19
Q

The promoter of PEPCK gene contains these two elements important for regulation

A

Insulin response element (IRE) and cyclic AMP response element (CRE)

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20
Q

Enzyme that catalyzes:
Fructose-1,6-bisphosphate –> Fructose-6-phosphate

A

Fructose-1,6-bisphosphatase

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21
Q

Negative allosteric regulators of Fructose-1,6-bisphosphatase (2)

A

Fructose-2,6-bisphosphate and AMP

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22
Q

Fructose-2,6-bisphosphate levels have this effect on gluconeogenesis

A

Decrease

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23
Q

Fructose-2,6-bisphosphate levels have this effect on glycolysis

A

Increase

24
Q

Fructose-2,6-bisphosphate levels are regulated by this

A

Insulin/glucagon ratio

25
Q

Glucagon decreases Fructose-2,6-bisphosphate levels by stimulating this pathway

A

AC –> cAMP –> PKA –> phosphorylated/inactivated PFK-2

26
Q

Fructose-2,6-bisphosphate levels are increased by glucagon or insulin?

A

Insulin

27
Q

Fructose-2,6-bisphosphate levels are decreased by glucagon or insulin?

A

Glucagon

28
Q

Enzyme that catalyzes:
Glucose-6-phosphate –> glucose

A

Glucose-6-phosphatase

29
Q

Cellular location of Glucose-6-phosphatase

A

Lumen face of ER membrane

30
Q

4 signals for gluconeogenesis

A

Fasting
Prolonged exercise
High protein diet
Stress/injury

31
Q

Decreased NAD+ has this effect on gluconeogenesis

A

Decreases

32
Q

Alcohol impairs gluconeogenesis by decreasing the levels of this

A

NAD+

33
Q

Total # of ATP and NADH required per glucose generated from pyruvate

A

6 ATP, 2 NADH

34
Q

For the first 2 hours after eating, tissues utilize this glucose source

A

All use exogenous glucose from the diet

35
Q

Second most readily available source of blood glucose after exogenous glucose from diet

A

Glycogen

36
Q

Last resort for blood glucose levels while fasting

A

Gluconeogensis

37
Q

Tissues using glucose from glycogen or hepatic gluconeogenesis 2+ hours after eating

A

All except liver
Muscle and adipose at diminished rates

38
Q

Tissues using glucose from hepatic gluconeogensis or glycogen at 3+ hours after eating

A

All except liver
Muscle and adipose at rates intermediate between hours 2 and 4

39
Q

Major fuel source of brain 1-3 hours fasting

A

Glucose

40
Q

Major fuel source of brain 4 hours fasting

A

Glucose > ketone bodies

41
Q

Major fuel source of brain 5 hours fasting

A

Ketone bodies > glucose

42
Q

Organ most sensitive to low glucose levels

A

Brain (takes 4+ hours fasting to start using other fuel source of ketone bodies)

43
Q

Tissues using glucose from hepatic and renal gluconeogenesis 4 hours of fasting

A

Brain, RBCs, Renal medulla
Small amount by muscle

44
Q

Tissues using glucose from hepatic and renal gluconeogenesis at 5 hours fasting

A

Brain at a diminished rate
RBCc, renal medulla

45
Q

Origin of blood glucose at 1 hour fasting

A

Exogenous

46
Q

Origin of blood glucose at 2 hours fasting

A

Glycogen
Hepatic gluconeoegenesis

47
Q

Origin of blood glucose at 3 hours fasting

A

Hepatic gluconeogenesis
Glycogen

48
Q

Origin of blood glucose at 4 hours fasting

A

Hepatic and renal gluconeogenesis

49
Q

Origin of blood glucose at 5 hours fasting

A

Hepatic and renal gluconeogenesis

50
Q

Tissues with glucagon receptors

A

Liver and adipose

51
Q

In adipose tissue, glucagon activates this pathway to cleave fatty acids and glycerol

A

PKA pathway

52
Q

Steroid drug that stimulates gluconeogenesis; induces PEPCK synthesis

A

Dexamethasone

53
Q

Dexamethosone stimulates gluconeogenesis by inducing this enzyme

A

PEPCK

54
Q

Dexamethosone causes breakdown of this

A

Muscle protein to amino acids

55
Q

Does dexamethosone (glucocorticoid) affect glucose levels?

A

Yes - hyperglycemia due to increased gluconeogenesis

56
Q

Does dexamethosone (glucocorticoid) affect lacid acid levels?

A

No lactic acidosis - lactate is taken for gluconeogenesis

Biochem (21 decks)

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