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Biochemistry > Unit 4: Chapter 17, Regulation of Gluconeogenesis and Glycolysis > Flashcards

Unit 4: Chapter 17, Regulation of Gluconeogenesis and Glycolysis Flashcards

1
Q

gluconeogensis and glycolysis are _________ _________

A

reciprocally regulated
Ex. Glycolysis will predominate when gluconeogenesis is inhibited and vise versa

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2
Q

Reciprocally regulated

A

when one is activated, other is inhibited

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3
Q

___ will predominate when glucose is abudant and ATP is needed

A

glycolysis

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4
Q

___ will predominate when glucose is scarce

A

gluconeogenesis

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5
Q

If both gluconeogenesis and glycolysis are active at the same time..

A

the net result would be the hydrolysis of 4 nucleotide triphosphates per reaction cycle since it is futile cycle

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6
Q

What is key regulation enzyme in gluconeogenesis?

A

Intervoncversion of fructose 6 phosphate and fructose 1,6 biphosphate catalyzed by fructose 1,6 biphosphatase

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7
Q

How is fructose 1,6 biphosphatase inhibited?

A

Inhibited by ADP, low energy charge
Since process is highly expensive when energy charge is low, the key enzyme is inhibited

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8
Q

How is fructose 1,6 biphosphatase activated?

A

Activated by high energy change

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9
Q

Evaluate following situation: When energy is needed and AMP concentration is high

A
  • if AMP is high indicates low energy
  • Glycolysis will be activated and gluconeogenesis will be inhibited
  • AMP activates PFK and inhibits F1,6 biphosphatase
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10
Q

Evaluate following situation: When energy level is high, ATP level is high, and citrate concentration is high

A
  • citrate indicates energy charge is high and biosynthetic intermediates
  • glycolysis inhibited and gluconeogenesis will be activated
  • PFK will be inhibited and F 1,6 biphosphatase will be activated
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11
Q

What indicates cell is rich in biosynthetic precursors and anabolic pathways are favored (require energy so gluconeogenesis)?

A

Citrate, alanine, CoA, and ATP

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12
Q

Glycolysis occurs where

A

Cytosol

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13
Q

Gluconeogenesis occurs where

A

Liver and kidneys

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14
Q

Balance between glycolysis and gluconeogenesis in liver is sensitive to

A

maintain blood glucose concentration

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15
Q

After a meal, blood glucose is abundant which effects

A
  • Hormone glucagon concentration in blood falls and insulin concentration rises
  • Gluconeogenesis will be inhiited and glyucolysis will predomiante
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16
Q

What is a potent activator of PFK?

A

Fructose 2,6 biphosphate

17
Q

Fructose 2,6 biphopshate inhibits what in gluconeogenesis

A

Fructose 1,6 biphosphate

18
Q

How is the amount of fructose 2,6 biphosphate controlled of rise and fall in blood glucose concentration?

A

Controlled by bifunctional regulaotry enzyme PFK2 and fructose phosphatase 2

19
Q

Both PFK2 and FBPase 2 are present in ________

A

single polypeptide chain

20
Q

How are PFK2 and FBPase controlled by

A

phosphorylation of single serine residue by protein kinase / phosphoprotein phosphatase

21
Q

PFK2/FBPase 2: When glucose level is low, glucagon hormone level is up

A
  • Protein kinase A will be activated and will phosphorylate serine on PFK2
  • PFK2 inactivated and FBPase 2 activated
  • FPase 2 catalyzed fructose 2,6 biphosphaate to fructose 6 phosphate (dephosphorylation)
  • concentration is lower
  • glycolysis in ihhibited and glucogenesis is activated
22
Q

PFK2/ FBPase 2: When glucose level is high, insulin concentration rises

A
  • Stimulates glycolysis and gluconeogensis inhibited
  • Remove phosphase in PFK2 by phosphoprotein phosphatase
  • PFK2 activated and FBPase 2 inhibited
  • PFK2 catalyzed fructose 6 phosphate to fructose 2,6 biphosphate (phosphorylation)
23
Q

Coordinated control of glycolysis and glucogenesis is faciliated by

A

location of kinase and phosphotase domain on same polypeptide chain as regulatory domain

24
Q

What does cori cycle refer to?

A
  • Recyclign of glucose due to glycolysis in muscle and gluconeogensis in liver
  • Glycolysis in fast twitch skeletal muslce produces lactate in conditions of O2 debt
  • Glucogeonesis recycles lactate to glucose after it is first oxidfized to pyruvate which occurs in the liver
25
Q

What shares stress of vigorous exercise and not just muscle?

A

Liver

26
Q

If a tiger is chasing Dr. Kim causing Dr. Kim to run as fast as possible. What is going on with glycolysis and gluconeogenesis in liver and leg muscle?

A
  • Gluconeogeneiss will be abudnant in liver and try to convert lactate to glucose
  • Muscle needs energy so glycoolysis will be abundant

Biochemistry (17 decks)

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