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MCM > Carbohydrate Metabolism > Flashcards

Carbohydrate Metabolism Flashcards

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1
Q

Where is GLUT1 Located and what is its affinity?

A

Ubiquitous-high in RBCs and Brain. High affinity

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2
Q

GLUT2 Location and Affinity

A

Liver - Low affinity

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3
Q

GLUT3 Location and Affinity

A

Neurons - High affinity

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4
Q

GLUT4 Location and Affinity

Regulated by what?

A

Skeletal Muscle, heart, adipose tissue

-Insulin Dependent

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5
Q

How Does insulin regulate GLUT4

A

signals fusion of GLUT4 vesicles with the plasma membrane

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6
Q

How many molecules of pyruvate from glucose

A

2

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7
Q

What are the three phases of glycolosis

A

Investment, splitting, payoff

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8
Q

What does the enzyme hexokinase do?
Where is it located?
What inhibits its action?

A

Glucose to Glucose 6-P
Present in all cells
Inhibited by its product Glucose 6-P

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9
Q

What does the enzyme glucokinase do?
Where is it located?
What inhibits its action?
What promotes it action?

A

Glucose to Glucose 6-P
Present in (liver and pancreatic b-cells)
Inhibited by glucagon and Fructose 6-P
Promoted by glucose, fructose 1-P, and Insulin

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10
Q

What does the enzyme phosphofructokinase-1 do?
What makes it special for glycolosis?
What inhibits its action?
What promotes its action?

A

Fructose 6-P to Fructose 1,6-BP
It is the rate limiting step in glycolysis
It is inhibited by ATP and Citrate
It is promoted by AMP and Fructose 2,6-BP

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11
Q 
What does the enzyme glyceraldehyde 3-P dehydrogenase do?
What product(s) are produced?
A

Glyceraldehyde 3-P to 1,3-bisphosphoglycerate

NADH is produced

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12
Q 
What does the enzyme phosphoglycerate kinase do?
What product(s) are produced?
A

1,3-bisphosphoglycerate to 3-phosphoglycerate

ATP is produced

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13
Q 
What does the enzyme pyruvate kinase do?
Is its action reversible or irreversible?
What product(s) are produced?
What inhibits its action?
What promotes its action?
A

phosphonolatepyruvate (PEP) to pyruvate
Irreversible
ATP
It is inhibited by Alanine, ATP, and Glucagon
It is promoted by Insulin and Fructose 1,6-BP

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14
Q

What does F6P do to Glucokinase?

A

It translocates Glucokinase (GK) to the nucleus and acts as an inhibitor.

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15
Q

When is PFK-1 active

A

Dephosphorylated: kinase

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16
Q

When is PFK-1 inactive

A

Phosphorylated: phosphatase

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17
Q

High insulin on Pyruvate Kinase (PK)

A

stimulates protein phosphatase
dephosphorylation of PK
ACTIVE

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18
Q

Low insulin on Pyruvate Kinase (PK)

A

cAMP activates PKA
Phosphorlation
PK INHIBITED

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19
Q

For what pathway is Glucose 6-P a precursor

A

Pentose phosphate pathway

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20
Q

What are the fates of pyruvate?

A

Lactate
Acetyl CoA
Alanine
Ethanol

21
Q

What do disorders of glycolysis cause?

A

hemolytic anemia

22
Q

What mechanism(s) do RBCs use to produce ATP

A

glycolysis

23
Q

Fed State

A
  • abundant glucose
  • increased trapping (phosphorylation)
  • increased rates of glycolosis
  • production of glycogen
  • decreased gluconeogenesis
24
Q

Fasting State

A
  • low glucose
  • decreased uptake
  • more catabolism
  • less storage
  • increase in gluconeogenesis
  • increase in glycogenolysis
25
Q

Type 1 diabetes cause

A

deficiency due to loss of pancreatic b-cells

26
Q

Type 2 diabetes

A

insulin resistance hat progresses to loss of b cell function

27
Q

What can defects in some glycolytic enzymes cause

A

hemolytic anemia

*clinical marker of elevated lactate dehydrogenase

28
Q

What is Tarui Disease (GSD VIII)

A

Deficient in PFK-1 (rate limiting step of glycolysis)
exercise-induced muscle cramps and weakness
hemolytic anemia

29
Q

When does gluconeogenesis occur

A

when glucose and glycogen stores are depleated

30
Q

What are the major precursors of gluconeogenesis

A

Amino Acids, lactate, and glycerol

31
Q

Where does gluconeogenesis occur

A

liver
kidney
small intestine

32
Q

What are positive regulators of gluconeogenesis?

A

Glucagon, Citrate, cortisol, thryoxine, acetyl CoA

33
Q

What are negative regulators of gluconeogenesis?

A

ADP, AMP, Fru 2,6-BP

34
Q

What are positive regulators of glycolysis?

A

Glucose, insulin, AMP, Fructose 2,6-BP, Fru 1,6-BP

35
Q

What are negative regulators of glycolysis

A

Glucagon, ATP, citrate, Glc 6-P, alanine

36
Q

What are the four important enzymes of gluconeogenesis?

A
  • pyruvate carboxylase
  • phospohoenolpyruvate carboxylase
  • fructose 1,6-bisphosphatase
  • glucose 6-phosphatase
37
Q

What does the enzyme pyruvate carboxylase (PC) do?
Where is it located?
What is its cofactor?

A

Pyruvate converted to oxaloacetate (OAA)
mitochondrial
Biotin is a cofactor

38
Q

What does the enzyme phosphoenolpyruvate carboxykinase (PEPCK) do?

A

Oxaloacetate (OAA) to phosphoenolpyruvate (PEP)

39
Q

What does the enzyme Fructose 1,6-Bisphosphatase do?
Why is this enzyme important for gluconeogenesis?
What activates this enzyme?
What inhibits this enzyme?

A

Fructose 1,6-BP to Fructose 6-P
Rate limiting step of gluconeogenesis
Activated by cortisol and citrate
Inhibited by AMP and F2,6-BP

40
Q

What does the enzyme glucose 6-phospohatase do?
Where is it active/located
What activates this enzyme?

A

Glucose 6-P to Glucose
Only in Liver, kidneys, SI, and pancreas
Activated by cortisol

41
Q

What does the Cori Cycle link?

A

Links the lactate produced from anerobic glycolysis in RBS and exercising muscle to gluconeogenesis in liver

42
Q

What can a deficiency in F1,6-BP cause?

A

hemolytic anemia, lactic acidosis, hyperventilation

43
Q

What is Fanconi-Bickel Syndrome

A

Mutation of GLUT 2 transporter

  • unable to take up glucose, fructose, and galactose
  • failure to thrive, rickets
  • treat with vit D
44
Q

What can cause galactosemia

A

Deficiency in glucose 1P uridyltransferase (GALT)

Deficiency in galactokinase

45
Q

What does the Pentose Phosphate Pathway Produce?

A

No energy
Sugar for DNA and RNA formation
Produces NADH

46
Q

What does the PPP do?

A

Oxidation of G6P to ribulose 5-P

-Reduction of NADP+ to NADPH

47
Q

What does the enzyme G6P dehydrognase do?

A

Rate limiting step of PPP

reduces NADP+ to NADPH and exidized G6P to 6-phosphoglycono-lactone

48
Q

Where is glycogen stored

A

liver, muscle, and other tissues

MCM (6 decks)

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