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Bio 540 - Biochem > Exam 3 - Glycolysis Regulation > Flashcards

Exam 3 - Glycolysis Regulation Flashcards

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1
Q

What reaction product strongly inhibits the function of hexokinase?

A

Glucose 6-phosphate

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2
Q

Is Hexokinase always operating at Vmax?

A

Yes

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3
Q

Glucokinase is [] inhibited by glucose 6-phosphate

A

NOT

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4
Q

Glucokinase activity is regulated by [] of the enzyme between the cytoplasm and the []

A
  • translocation
  • nucleus
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5
Q

Glucokinase

  • GK-RP is [] in the nucleus
  • High levels of [] will remove the repressor, followed by [] of the now [] protein to the cytosol
A
  1. inactive
  2. Glucose
    1. translocation
    2. Active
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6
Q
  • Increased levels of [] promote translocation of glucokinase to the nucles…making it more []
A
  1. Fructose 6-Phosphate
  2. inactive
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7
Q

What does Glucose 6-phosphatase do?

A

Converts Glucose 6-phosphate to Glucose….in the liver

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8
Q

What are the benefits of the futile cycle in the liver of: Glucose < —> Glucose 6-phosphate?

A
  1. Phosphate pools are finite and Glucose 6-phosphatase remakes phosphates
  2. Provides fine control for directionality of the system.
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9
Q

What is the “first committed” step of Glycolysis?

What type of regulation is it subject to?

A
  1. Fructose 6-Phosphate –> Fructose 1,6-Bisphosphate
    1. done by 6-phosphofructo-1-kinase
  2. Allosteric regulation
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10
Q

What are the positive/negative effector molecules on 6-phosphofructo-1-kinase?

A
  • Positive
    • AMP
    • Fructose 2,6-Bisphosphate
  • Negative
    • ATP
    • Citrate
    • H+
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11
Q

How is AMP a negative effector molecule in Gluconeogenesis?

A
  • AMP binds to 6-phosphofructo-1-kinase as an effector
  • Higher levels of AMP negatively effect Fructose 1,6-bisphosphatase (step in Gluconeogenesis)
  • If you were to remove AMP as an effector molecule it would then stop glycolysis and change to gluconeogenesis
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12
Q

If pH levels climb too high, what will happen to glycolysis?

Where is H+ an effector molecule in Glycolysis?

A
  • Glycolysis will shut off if pH levels rise too much from the production of Lactate and H+
  • H+ will act as an effector molecule on 6-phosphofructo-1-kinase
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13
Q

With abundant energy supplied by lipids, glycolytic pathway is [] regulate so that blood [] levels can be maintained for tissue not able to oxidize lipids.

A
  1. down
  2. glucose
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14
Q

Fructose 2,6-bisphosphate is a [] regulator of 6-phosphofructo-1-kinase and a [] regulator of fructose 1,6-bisphosphatase

A
  1. Positive
  2. negative
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15
Q

What bifunctional enzyme creates Fructose 2,6-bisphosphate?

A

6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase

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16
Q

What bifunctional enzyme creates Fructose 6-phosphate from Fructose 2,6-bisphosphate?

A

6-phosphofructo-2-kinase/fructose 2,6 bisphosphatase

17
Q

6-phosphofructo-2-kinase/fructose 2,6 bisphosphatase is [] regulated by phosphorylation/dephosphorylation….

A

Covalently

18
Q

When 6-PF-2-K/F-2,6-P’ase is phosphorylated, which part of the enzyme is active?

What is going on with Blood Glucose when this happens?

What enzyme does the phosphorylating here?

A
  • F-2,6-P’ase is active, meaning your creating Fructose 6-Phosphate from Fructose 2,6-bisphosphate
  • Increased levels of Glucagon, which means LOW blood glucose
  • Protein Kinase A
19
Q
  1. When 6-PF-2-K/F-2,6-P’ase is dephosphorylated, which part of the enzyme is active?
  2. What is going on with Blood Glucose when this happens?
  3. What enzyme does the dephosphorylating here?
A
  • 6-PF-2-K is active when the enzyme is dephosphorylated
  • Blood Glucose would be higher at this point
  • Phosphoprotein phosphatase
20
Q

How does Glucagon affect the levels of F-2,6-BP?

A
  • Glucagon activates adenylate cyclase
  • Adenylate cyclase converts ATP into cAMP
  • cAMP activates protein kinase A => PKA phosphorylates 6-PF-2-K/F-2,6-P’ase causing the production of Fructose 6-phosphate from Fructose 2,6-bisphosphate
21
Q

Insulin counters Glucagon by activation of this cAMP destrtorying enzyme - [] []…

A

cAMP phosphodiesterase

22
Q

The kinase mediated signaling cascade within the cell caused by Inulin targets 3 “things” for regulation at once.

What are these targets and how does the cascade effect each?

A
  1. cAMP –>AMP - positive effect, increasing AMP
  2. cAMP activating Protein Kinase A
    1. represses protein Kinase A
  3. Phosphoprotein Phosphatase
    1. positive effect - leads to the dephosphorylation of PH-2-K/F-2,6-BP
23
Q

How does insulin effect glycolysis in response to high blood glucose?

A
  • It creates AMP from cAMP - this positively effects 6-PF-1-K in glycolysis
  • It inhibits Protein Kinase A activity => increase in activity from phosphoprotein phosphotase => which means more Fructose 2,6-BP is produced because that bifunctional enzyme is dephosphorylated by Phosphoprotine phospotase.
  • Fructose 2,6-BP is a positive effect like AMP.
24
Q

[] and [] Use G proteins to activate adenylate cyclase causing the proudction of cAMP and the activation of Protein Kinase A…

A

Glucagon and Epinephrine

25
Q

Adenylate Kinase…

2 ADP –> ???

A

1 ATP

1 AMP

26
Q

In the heart - which part of the bifunctional enzyme 6-PF-2-K/F-2,6-BP is active when dephosphorylated?

A

F-2,6-BP is active (reverse of the liver)

So, when not stimulated by Epinephrine - the heart is not running glycolysis (at a higher rate at least).

27
Q

Pyruvate kinase is controlled by what kind of regulation?

A

Covalent Regulation

Phosphorylation/Dephosphorylation

28
Q

How does glucagon effect pyruvate kinase?

A
  • Phosphorylates Pyruvate Kinase, INACTIVATING IT
  • Works through cAMP –> activation of protein Kinase A
29
Q

How does Insulin effect pyruvate Kinase?

A
  • Dephosphorylation of pyruvate kinase
    • ACTIVATING IT
  • Works through blocking cAMP, and positively effecting phosphoprotein phosphatase to remove phosphate from pyruvate kinase.
30
Q

What are effector molecules for Pyruvate Kinase?

What are their effects?

A
  • Positive
    • Fructose 1,6-bisphosphate
  • Negative
    • ATP, alanine

Bio 540 - Biochem (14 decks)

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