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Flashcards in Regulation of Carbohydrate Metabolism Deck (70)
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1

When blood sugar increases:
Insulin is ____

released

2

Insulin is released, which leads to the
dephosphorylation of:

 

1. PFK-2

2. Pyruvate kinase 

3. Pyruvate dehydrogenase 

4. Glycogen synthase  

5. Glycogen phosphorylase

3

When blood sugar decreases: ____ is released

Glucagon

4

glucagon release leads to the ______

•PFK-2 (phosphatase active, ↓ F2,6BP)

Pyruvate kinase (inactive)


•Pyruvate dehydrogenase (E1 inactive)

Glycogen synthase (inactive) •Glycogen phosphorylase (active)

phosphorylation 

5

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

 

leads to active

•Glycolysis
•CAC
•Glycogen synthesis (Glycogenesis)

6

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 

Gluconeogenesis


Glycogen breakdown (Glycogenolysis)

7

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

near 

8

when a reaction is rate limiting 

[S] ____ [S]eq

[S] > [S]eq

9

when rxn is rate limiting 

[P] ___ [P]eq

[P] < [P]eq

10

when rxn is rate limiting 

∴ΔG = ___

negative

11

___ (3) catalyze glycolytic steps that are rate limiting

Hexokinase,  Phosphofructokinase, and Pyruvate Kinase 

12

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

much faster than net flux through that step

13

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

highly exergonic

14

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

the same ones that are rate limiting in glycolysis 

Hexokinase, Phosphofructokinase, and Pyruvate Kinase

15

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

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

16

which point IS a good point to regulate glycolysis?

PFK 

or pyvutate kinase

17

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

 the concentration of its substrate, PEP, will be elevated

18

PFK is allosterically inhibited by 

ATP as a feedback inhibitor

19

___ effectively competes with ATP for binding at the allosteric site

1. AMP

 2. F2,6BP

20

what speeds up glyciolysis? why? 

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

21

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

 stabilizing positive charge (R162) near the negatively charged substrate

22

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

destabilizing negative charge (E161) near the negatively charged substrate

23

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

feedback inhbiition of glyolysis

24

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

FBPase 

25

effect of F2,6BP and AMP on gluyconeogensis?

slow gluconeogensis

26

difference between FBP and  F2,6BP structurally? 

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

27

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

kinase domain, called PFK-2

28

what is PFK-2? 

 catalytic site in the kinase domain 

29

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

phosphatase domain,  FBPase-2 

30

increased CAMP