Carbohydrate Metabolism Flashcards

1
Q

Normal blood glucose level

A

90-108 mg/dl

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2
Q

hyperglycemic

A

elevated blood glucose

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3
Q

hypoglycemic

A

low blood glucose <45mg/dl

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4
Q

Glucose Transporter Isoforms

A

GLUT 1
GLUT 2
GLUT 3
GLUT 4
GLUT 5

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5
Q

GLUT 4

A

uptake of glucose from blood to cell in muscle, heart and adipose tissue

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6
Q

Pathways of glycolysis

A

Anaerobic
Aerobic

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7
Q

What is glycolysis

A

the breakdown of glucose to pyruvate
most common pathway
sole source of energy for erythrocytes

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8
Q

How many reactions take place in Anaerobic Glycolysis

A

10

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9
Q

how many times is glucose phosphorylated during anaerobic glycolysis, where do these take place?

A

2 times, during the first and third reactions

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10
Q

During glucose to pyruvate glycolysis how many carbons and how many phosphoryl groups are produced? What is the net cost?

A

Yield:
6 carbons
2 phosphoryl groups
Cost:
2 ATP

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11
Q

Which molecules are formed during the fourth anaerobic glycolysis reaction?

A

Dihydroxyacetone phosphate
glyceraldehyde 3 phosphate

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12
Q

What is Dihydroxey acetone phosphate converted to?

A

Glyceraldehyde 3 phosphate

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13
Q

Where does glyceraldehydde 3 phosphate get its second phosphoryl group from?

A

Inorganic Phosphate (Pi)

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14
Q

During the conversion of dihydroxyacetone phosphate to glyceraldehyde 3 phosphate which substance is reduced?

A

NAD+ to NADH

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15
Q

Where does 1,3 biphosphoglycerate donate its phosphoryl groups?

A

6th and 10th reaction

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16
Q

How many major phases does glycolysis have and what are they?

A

Preparatory phase (first 5 steps)
Payoff phase (last 5 steps)

17
Q

Anaerobic Glycolysis Step 1

A

Prep Phase
-Phosphorylation of glucose
-Glucose + ATP >Hexokinase>ADP+ Glucose 6 phosphate
-Irreversible
-Control Point

18
Q

Anaerobic Glycolysis Step 2

A

Prep Phase
Glucose 6 phosphate <phosphoglucomutase> Fructose 6 phosphate
-Aldose to Ketose
-Reversible</phosphoglucomutase>

19
Q

Phosphoglucomutase

A

Phosphohexose Isomerase
Glucose 6 phosphate to Fructose 6 phosphate

20
Q

Anaerobic Glycolysis Step 3

A

Prep Phase
Phosphorylation of Fructose 6 phosphate + ATP <Phosphofructokinase (PFK-1) to Fructose-1,6 Diphosphate (biphosphate) + ADP
-2nd priming reaction
-Irreversible

21
Q

Importance of the PFK-1 Reaction

A

Rate limiting step in glycolysis
-inhibited by high ATP / High citrate
-Stimulated by Low atp/ low citrate

22
Q

Why is PFK the key and not Hexokinase?

A

Glucose 6 phosphate, glycolytic intermediate can also be converted to clycogen, this is the first committed step and is catalyzed by PFK

23
Q

Anaerobic Glycolysis Step 4

A

Prep Phase
Cleavage of Fructose 1,6 Diphosphate to BOTH Glyceraldehyde 3 phosphate (ALDOSE) and Dihydroxyacetone Phosphate (KETOSE) by aldolase
-Reversible

24
Q

Anaerobic Glycolysis Step 5

A

Final Prep Phase
Interconversion of Triose PhosphatesOnly glyceraldehyde 3 phosphate (aldose) can be degraded in subsequent reactions
-Catalyzed by Triose Phosphate Isomerase
-Reversible
-Rapidly converts Dihydroxyacetone to glyceraldehyde 3 phosphate

25
Q

Anaerobic Glycolysis Step 6

A

Payoff Phase
Oxidation of Glyceraldehyde 3 phosphate + NAD+ <glyceraldehyde 3 phosphate dehydrogenase> 1,3 Biphosphoglycerate + NADH + H+
-Reversible
-First of 2 energy conserving reactions

26
Q

Importance of Glyceraldehyde 3 phosphate Dehydrogenase reaction

A

Uses NAD formed from lactate

27
Q

Anaerobic Glycolysis Step 7

A

Payoff Phase
Transfer of phosphate from 1,3 Biphosphoglycerate to ADP
1,3 Biphosphoglycerate + ADP <Phosphoglycerate> ATP + 3 phosphoglycerate
-Reversible Reaction
-Substrate level phosphorylation</Phosphoglycerate>

28
Q

Anaerobic Glycolysis Step 8

A

Payoff Phase
3 phosphoglycerate <phosphoglycerate> 2 phosphoglycerate
-moves phosphoryl group from C3 to C2
-Reversible</phosphoglycerate>

29
Q

Anaerobic Glycolysis Step 9

A

Payoff Phase
Dehydration
2 phosphoglycerate <ENOLASE> phosphoENOpyruvate and H2O
Reversible</ENOLASE>

30
Q

Anaerobic Glycolysis Step 10

A

Payoff Phase
Transfer of phosphate group to ADP
Phosphoenolpyruvate +ADP >Pyruvate Kinase> Pyruvate and ATP
Essentially irreversible