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MCP > Regulation of Carbohydrate Metabolism > Flashcards

Regulation of Carbohydrate Metabolism Flashcards

1
Q

When blood sugar increases:
Insulin is ____

A

released

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2
Q

Insulin is released, which leads to the
dephosphorylation of:

A
  1. PFK-2
  2. Pyruvate kinase
  3. Pyruvate dehydrogenase
  4. Glycogen synthase
  5. Glycogen phosphorylase
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3
Q

When blood sugar decreases: ____ is released

A

Glucagon

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4
Q

glucagon release leads to the ______

•PFK-2 (phosphatase active, ↓ F2,6BP)

Pyruvate kinase (inactive)

•Pyruvate dehydrogenase (E1 inactive)

Glycogen synthase (inactive) •Glycogen phosphorylase (active)

A

phosphorylation

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5
Q

Insulin is released, which leads to the
dephosphorylation of:
PFK-2, Pyruvate kinase, Pyruvate dehydrogenase, Glycogen synthase, Glycogen phosphorylase

leads to active

A
  • Glycolysis
  • CAC
  • Glycogen synthesis (Glycogenesis)
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6
Q

When blood sugar decreases: Glucagon is released, which leads to the phosphorylation of:PFK-2, Pyruvate kinase, Pyruvate dehydrogenase, Glycogen synthase, Glycogen phosphorylase

this leads to active

A

Gluconeogenesis

Glycogen breakdown (Glycogenolysis)

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7
Q

enzymes that operate ____equilibrium may be so efficient that a reduction in their activity will have little or no effect on the overall flux.

A

near

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8
Q

when a reaction is rate limiting

[S] ____ [S]eq

A

[S] > [S]eq

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9
Q

when rxn is rate limiting

[P] ___ [P]eq

A

[P] < [P]eq

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10
Q

when rxn is rate limiting

∴ΔG = ___

A

negative

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11
Q

___ (3) catalyze glycolytic steps that are rate limiting

A

Hexokinase, Phosphofructokinase, and Pyruvate Kinase

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12
Q

When an enzyme catalyzes a reaction that is near equilibrium, it means that its rate of catalysis is

A

much faster than net flux through that step

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13
Q

When an enzyme catalyzes a reaction that is ____, it means that its rate of catalysis limits flux through that step in a pathway

A

highly exergonic

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14
Q

what steps need to be bypassed (bc they are highly exergonic) in glucogenogensis?

A

the same ones that are rate limiting in glycolysis

Hexokinase, Phosphofructokinase, and Pyruvate Kinase

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15
Q

which point is not the optimal point to regualte glycolysis? why?

A

Bypass III is not the optimal point to regulate Glycolysis because G6P is required for other pathways

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16
Q

which point IS a good point to regulate glycolysis?

A

PFK

or pyvutate kinase

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17
Q

why does pyruvate kinase need to be turned off during glucogenogenssi?

A

the concentration of its substrate, PEP, will be elevated

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18
Q

PFK is allosterically inhibited by

A

ATP as a feedback inhibitor

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19
Q

___ effectively competes with ATP for binding at the allosteric site

A
  1. AMP
  2. F2,6BP
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20
Q

what speeds up glyciolysis? why?

A

AMP effectively competes with ATP for binding at the allosteric site signaling
Glycolysis to speed up to replenish the ATP supply

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21
Q

When an allosteric activator binds, PFK assumes a conformation that places a ___ near a ____

A

stabilizing positive charge (R162) near the negatively charged substrate

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22
Q

when an allosteric inhibitor binds to PFK, the conformation assumed places a

A

destabilizing negative charge (E161) near the negatively charged substrate

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23
Q

F2,6BP prevents ____ because it competes with ATP for binding on PFK

A

feedback inhbiition of glyolysis

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24
Q

, F2,6BP and AMP bind to an allosteric site on ____and inhibit, thereby slowing Gluconeogenesis

A

FBPase

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25
Q

effect of F2,6BP and AMP on gluyconeogensis?

A

slow gluconeogensis

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26
Q

difference between FBP and F2,6BP structurally?

A

The second phosphoryl on F2,6BP is on the C2 hydroxyl instead of on the C1 hydroxyl as is the case for FBP

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27
Q

In the dephosphorylated state, the catalytic site in the ____ domain ss active

A

kinase domain, called PFK-2

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28
Q

what is PFK-2?

A

catalytic site in the kinase domain

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29
Q

In the phosphorylated state, the catalytic site in the ____ domain is active

A

phosphatase domain, FBPase-2

30
Q
A

increased CAMP

31
Q
A

increased enzyme phoshporylation

32
Q
A

activation of FBP-ase-2 and inactivation of PFK-2

33
Q
A

dec F26P

34
Q
A
  1. inhibition of PFK
  2. activation of FBPase
35
Q
A

increased glucogenosesis

36
Q

blood Glu concentration is high, insulin promotes decreased enzyme phosphorylation resulting in increased ___

A

F2,6P —> inc glycolysis, dec gluconeogesnsis

37
Q

Hormonal regulation of ___in response to blood [Glu] allows selective activation of the pathway needed, while turning off the pathway not needed

A

[F2,6BP]

38
Q

Pyruvate Kinase is activated by

A

FBP

39
Q

Pyruvate Kinase is also inhibited by

A
  1. phosphorylation induced by Glucagon
  2. acetyl coa
  3. atp
40
Q

Pyruvate Carboxylase is activated by ____

A

Acetyl-CoA

41
Q

Glucagon causes a decrease in the level of

A

Glucokinase & PFK (Glycolytic enzymes)

42
Q

Glucagon causes an increase in the level

A

PEPCK, FBPase, and G6Pase ( Gluconeogenic enzymes)

43
Q

Insulin causes a decrease in the level of the

A

PEPCK (Gluconeogenic enzyme)

44
Q

The synthesis/breakdown pathways of glycogen can be thought of as one big bypass. Only ____ is shared

A

phosphoglucomutase

45
Q

In the pathway leading to glycogen, ____is the enzyme regulated

A

glycogen synthase

46
Q

In the pathway that breaks down glycogen, ____is the enzyme regulated

A

glycogen phosphorylase

47
Q

An increase in cAMP activates Protein Kinase A which activates Phosphorylase Kinase, which activates ____

A

Glycogen Phosphorylase

48
Q

Active PKA nd Phosphorylase Kinase inhbiit

A

Glycogen Synthase

49
Q

Protein Kinase A inactivates

A

Phosphoprotein Phosphatase-1

50
Q

Insulin activates____ and reverses all of the changes caused by an active Protein Kinase A

A

Phosphoprotein Phosphatase-1

51
Q

Glucagon binds to a liver cell receptor which produces

A

cAMP –> glycogen breakdown –> release of Glucose to blood stream

52
Q

___ and ___binds to a liver cell receptor which produces cAMP –> glycogen breakdown –> release of Glucose to blood stream

A

Epinephrine and Glucagon

53
Q

Muscle cells have no ____ receptor

A

Glucagon receptor

they are not responsible for maintaining blood glucose

54
Q

However, muscle cells still need to respond to ____ to increase availability of Glu-6-P for ATP production

A

epinephrine

55
Q

Insulin increases ___ in muscle

A

increases number of glucose transporters —> inc Glu uptake

56
Q

inc glucose uptake in muscle leads to

A

inc glycogen sythnesis

57
Q

inc adipocytes uptake in muscle leads to

A

increased synthesis of triacylglycerols

58
Q

When blood Glu is low, Phosphorylase will be in the ____ and ___

A

Phosphorylated form and in the active r confirmation

59
Q

When blood Glu is high, ATP and G6P will be high and dephosphorylated Phosphorylase will be in the ____ confirmation

A

inactive T conformation

60
Q

what are E4 and E5?

A

Pyruvate Dehydrogenase Complex

61
Q

the Pyruvate Dehydrogenase Complex kinase is activated by

A

NADH and Acetyl-CoA to phosphorylate and inactivate E1

62
Q

___ and ____ inhibit the Kinase of the Pyruvate Dehydrogenase Complex

A

pyruvate and ADP

63
Q

Pyruvate Dehydrogenase Complex

The Phosphatase is activated by____to convert E1 back to the active form

A

calcium ion

64
Q

Pyruvate Dehydrogenase Complex

product inhibition of e3 occurs by

A

nadh

65
Q

Pyruvate Dehydrogenase Complex

E2 is inhibited by

A

Acetyl-CoA

66
Q

what inhbiits cit synthease?

A

citrate

Succ-CoA

67
Q

what inhibits isocitrate dehydrogenase?

A

NADH

ATP

68
Q

what inhbiits α-ketoglutarate DHase

A

NADH and Succ-CoA

69
Q

what activates isocitrate dehydrogenase?

A

ADP

70
Q
A

MCP (16 decks)

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