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Biochemistry > Exam 2 Lecture 16 Gluconeogenesis > Flashcards

Exam 2 Lecture 16 Gluconeogenesis Flashcards

1
Q

whole body needs about _ g glucose per day

A

160 g

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2
Q

daily glucose requirement of brain is about _ g

A

120 g

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3
Q

glucose present in body fluids is about _ g

A

20 g

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4
Q

glucose readily available from glycogen is about _ g

A

190 g

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5
Q

glycogen is the storage form of _

A

glucose

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6
Q

glycogen is stored where

A

liver and the muscle

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7
Q

what is the purpose of a glycogen reserve?

A

the reserve of 190 g is sufficeint to meet glucose needs for about a day (fasting)

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8
Q

gluconeogenesis occurs where?

A

liver and kidney

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9
Q

Major 3 precursors of gluconeogenesis:

A
  1. lactate
  2. amino acids
  3. glycerol
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10
Q

what is the 1st step in gluconeogenesis?

A

pyruvate first converted to oxaloacetate (OAA)

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11
Q

pyruvate is converted into OAA via

A

enzyme pyruvate carboxylase (PC)

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12
Q

why is the compartmentalization of PC into the mitochondria important?

A

malate shuttle transports OAA to cytoplasm

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13
Q

what is the 2nd step in gluconeogenesis?

A

OAA converted into PEP

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14
Q

OAA converted into PEP via?

A

phosphoenolpyruvate carboxykinase

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15
Q

what is the 3rd step in gluconeogensis?

A

PEP converted into 2-PG

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16
Q

PEP converted into 2-PG via?

A

enolase (same as in glycolysis)

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17
Q

what is the 4th step in gluconeogenesis?

A

2-PG converted into 3-PG

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18
Q

2-PG converted into 3-PG via

A

phosphoglycerate mutase (same as in glycolysis)

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19
Q

what is the 5th step in gluconeogenesis?

A

3-PG converted into 1,3-BPG

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20
Q

3-PG converted into 1,3-BPG via?

A

phosphoglycerate kinase (same as in glycolysis)

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21
Q

what is the last step in gluconeogenesis?

A

1,3-BPG into GAP

22
Q

1,3-BPG into GAP via?

A

glyceraldehyde 3-phosphate dehydrogenase (same as in glycolysis) GAPDH

23
Q

From GAP to glucose:

GAP + _ forms fructose 1,6-BP

A

DHAP

24
Q

glycerol enters the pathway via

A

DHAP

25
Q

lactate (and some amino acids) enters the pathway via

A

pyruvate

26
Q

amino acids enters the pathway via

A

OAA

27
Q

what is the rate limiting enzyme of gluconeogenesis?

A

Fructose 1,6-bisphosphatase

28
Q

From GAP to glucose:

in 2nd step, Fructose 1,6-bisphosphatase breaks down _ into _

A

fructose 1,6-BP to F6P

29
Q

From GAP to glucose:

in the 3rd step, F6P is _ to G6P via _

A

F6P is isomerized to G6P via phosphoglucose isomerase (same as in glycolysis)

30
Q

From GAP to glucose:

in the last step, G6P forms free glucose by the action of _. Free glucose can leave liver and enter blood.

A

glucose 6-phosphatase

31
Q

glucose 6-phosphatase is located where?

A

in the lumen of the ER

32
Q

gluconeogeneis “by-passes” the irreversible steps of glycolysis via what 4 enzymes NOT present in glycolysis?

A
  1. pyruvate carboxylase (PC)
  2. phosphoenolpyruvate carboxykinase
  3. fuctose 1,6-bisphosphatase
  4. glucose 6-phosphatase
33
Q

2 pyruvate enters into gluconeogenesis to form 1 molecule of _

A

glucose

34
Q

what are the 3 points of ATP/GTP consumption in gluconeogenesis?

A
  1. converting pyruvate into OAA
  2. converting OAA into PEP
  3. converting 3-PG into 1,3-BPG
35
Q

gluconeogenesis and glycolysis are _ regulated

A

reciprocally regulated

36
Q

what are the modulators/activators in glycolysis

A
  1. F-2,6-BP and AMP stimulates phosphofructokinase in glycolysis
  2. F-1,6-BP stimulates pyruvate kinase in glycolysis
37
Q

what are the modulators/inactivators in glycolysis

A
  1. ATP, citrate, and H+ de-stimulates phosphofructokinase in glycolysis
  2. ATP and alanine de-stimulates pyruvate kinase in glycolysis
38
Q

what are the modulators/activators in gluconeogenesis

A
  1. Citrate stimulates fructose 1,6-bisphosphatase in gluconeogenesis
39
Q

what are the modulators/inactivators in gluconeogenesis

A
  1. F-2,6-BP and AMP de-stimulates fructose 1,6-bisphosphatase in gluconeogenesis
  2. ADP de-stimulates PC and phosphoenolpyruvate carboxykinase
40
Q

glucagon, when released, stimulates a kinase or phosphatase?

A

kinase

41
Q

insulin, when released, stimulates a kinase of phosphatase?

A

phosphatase

42
Q

F6P is converted into fructose 2,6-BP via _

A

phosphofructokinase 2 (PFK2)

43
Q

PFK2 has what kind of domains?

A

a kinase and a phosphatase domain

44
Q

Fructose 2,6-BP is a strong signalling molecule for _

A

phosphofrutokinase (PFK; rate limiting step of glycolysis)

45
Q

the concentration of Fructose 2,6-BP is controlled what kind of enzyme?

A

a bi-functional enzyme with a kinase and a phosphatase domain: PFK2 and FBPase 2 (fructose bisphosphatase)

46
Q

T/F: Fructose 2,6-BP stimulates or inhibits glycolysis

A

true

47
Q

the activity of the bi-functional enzyme is regulated by what 2 hormones?

A

insulin and glucagon

48
Q

_ stimulates a phosphatase and PFK2 is activated so glycolysis is active

A

insulin stimulates a phosphatase and PFK2 is activated

glucose is abundant

49
Q

_ stimulates PKA and FBPase 2 is activated so glycolysis is inhibited and gluconeogenesis is stimulated

A

glucagon stimulates PKA and FBPase 2 is activated

when blood glucose is scarce

50
Q

The Cori Cycle:

lactate is produced in skeletal muscle and RBCs and can be converted back to pyruvate in the _. This location does the reverse to make pyruvate into _ so it can be thrown back into the blood and muscle can pick it up.

A

liver

glucose

Biochemistry (32 decks)

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