Carbohydrate Metabolism Flashcards Preview

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Flashcards in Carbohydrate Metabolism Deck (48):
1

Where is GLUT1 Located and what is its affinity?

Ubiquitous-high in RBCs and Brain. High affinity

2

GLUT2 Location and Affinity

Liver - Low affinity

3

GLUT3 Location and Affinity

Neurons - High affinity

4

GLUT4 Location and Affinity
Regulated by what?

Skeletal Muscle, heart, adipose tissue
-Insulin Dependent

5

How Does insulin regulate GLUT4

signals fusion of GLUT4 vesicles with the plasma membrane

6

How many molecules of pyruvate from glucose

2

7

What are the three phases of glycolosis

Investment, splitting, payoff

8

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

9

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

10

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

11

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

Glyceraldehyde 3-P to 1,3-bisphosphoglycerate
NADH is produced

12

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

1,3-bisphosphoglycerate to 3-phosphoglycerate
ATP is produced

13

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

14

What does F6P do to Glucokinase?

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

15

When is PFK-1 active

Dephosphorylated: kinase

16

When is PFK-1 inactive

Phosphorylated: phosphatase

17

High insulin on Pyruvate Kinase (PK)

stimulates protein phosphatase
dephosphorylation of PK
ACTIVE

18

Low insulin on Pyruvate Kinase (PK)

cAMP activates PKA
Phosphorlation
PK INHIBITED

19

For what pathway is Glucose 6-P a precursor

Pentose phosphate pathway

20

What are the fates of pyruvate?

Lactate
Acetyl CoA
Alanine
Ethanol

21

What do disorders of glycolysis cause?

hemolytic anemia

22

What mechanism(s) do RBCs use to produce ATP

glycolysis

23

Fed State

-abundant glucose
-increased trapping (phosphorylation)
-increased rates of glycolosis
-production of glycogen
-decreased gluconeogenesis

24

Fasting State

-low glucose
-decreased uptake
-more catabolism
-less storage
-increase in gluconeogenesis
-increase in glycogenolysis

25

Type 1 diabetes cause

deficiency due to loss of pancreatic b-cells

26

Type 2 diabetes

insulin resistance hat progresses to loss of b cell function

27

What can defects in some glycolytic enzymes cause

hemolytic anemia
*clinical marker of elevated lactate dehydrogenase

28

What is Tarui Disease (GSD VIII)

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

29

When does gluconeogenesis occur

when glucose and glycogen stores are depleated

30

What are the major precursors of gluconeogenesis

Amino Acids, lactate, and glycerol

31

Where does gluconeogenesis occur

liver
kidney
small intestine

32

What are positive regulators of gluconeogenesis?

Glucagon, Citrate, cortisol, thryoxine, acetyl CoA

33

What are negative regulators of gluconeogenesis?

ADP, AMP, Fru 2,6-BP

34

What are positive regulators of glycolysis?

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

35

What are negative regulators of glycolysis

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

36

What are the four important enzymes of gluconeogenesis?

-pyruvate carboxylase
-phospohoenolpyruvate carboxylase
-fructose 1,6-bisphosphatase
-glucose 6-phosphatase

37

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

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

38

What does the enzyme phosphoenolpyruvate carboxykinase (PEPCK) do?

Oxaloacetate (OAA) to phosphoenolpyruvate (PEP)

39

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

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

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

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

41

What does the Cori Cycle link?

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

42

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

hemolytic anemia, lactic acidosis, hyperventilation

43

What is Fanconi-Bickel Syndrome

Mutation of GLUT 2 transporter
-unable to take up glucose, fructose, and galactose
-failure to thrive, rickets
-treat with vit D

44

What can cause galactosemia

Deficiency in glucose 1P uridyltransferase (GALT)
Deficiency in galactokinase

45

What does the Pentose Phosphate Pathway Produce?

No energy
Sugar for DNA and RNA formation
Produces NADH

46

What does the PPP do?

Oxidation of G6P to ribulose 5-P
-Reduction of NADP+ to NADPH

47

What does the enzyme G6P dehydrognase do?

Rate limiting step of PPP
reduces NADP+ to NADPH and exidized G6P to 6-phosphoglycono-lactone

48

Where is glycogen stored

liver, muscle, and other tissues