Carbohydrate Metabolism Flashcards
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Where is GLUT1 Located and what is its affinity?
Ubiquitous-high in RBCs and Brain. High affinity
GLUT2 Location and Affinity
Liver - Low affinity
GLUT3 Location and Affinity
Neurons - High affinity
GLUT4 Location and Affinity
Regulated by what?
Skeletal Muscle, heart, adipose tissue
-Insulin Dependent
How Does insulin regulate GLUT4
signals fusion of GLUT4 vesicles with the plasma membrane
How many molecules of pyruvate from glucose
2
What are the three phases of glycolosis
Investment, splitting, payoff
What does the enzyme hexokinase do?
Where is it located?
What inhibits its action?
Glucose to Glucose 6-P
Present in all cells
Inhibited by its product Glucose 6-P
What does the enzyme glucokinase do?
Where is it located?
What inhibits its action?
What promotes it action?
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
What does the enzyme phosphofructokinase-1 do?
What makes it special for glycolosis?
What inhibits its action?
What promotes its action?
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
What does the enzyme glyceraldehyde 3-P dehydrogenase do? What product(s) are produced?
Glyceraldehyde 3-P to 1,3-bisphosphoglycerate
NADH is produced
What does the enzyme phosphoglycerate kinase do? What product(s) are produced?
1,3-bisphosphoglycerate to 3-phosphoglycerate
ATP is produced
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?
phosphonolatepyruvate (PEP) to pyruvate
Irreversible
ATP
It is inhibited by Alanine, ATP, and Glucagon
It is promoted by Insulin and Fructose 1,6-BP
What does F6P do to Glucokinase?
It translocates Glucokinase (GK) to the nucleus and acts as an inhibitor.
When is PFK-1 active
Dephosphorylated: kinase
When is PFK-1 inactive
Phosphorylated: phosphatase
High insulin on Pyruvate Kinase (PK)
stimulates protein phosphatase
dephosphorylation of PK
ACTIVE
Low insulin on Pyruvate Kinase (PK)
cAMP activates PKA
Phosphorlation
PK INHIBITED
For what pathway is Glucose 6-P a precursor
Pentose phosphate pathway
What are the fates of pyruvate?
Lactate
Acetyl CoA
Alanine
Ethanol
What do disorders of glycolysis cause?
hemolytic anemia
What mechanism(s) do RBCs use to produce ATP
glycolysis
Fed State
- abundant glucose
- increased trapping (phosphorylation)
- increased rates of glycolosis
- production of glycogen
- decreased gluconeogenesis
Fasting State
- low glucose
- decreased uptake
- more catabolism
- less storage
- increase in gluconeogenesis
- increase in glycogenolysis
