Green - Glucose and Fructose Metabolism

Question 1

Glycolysis Net Outcomes

Answer 1

2 ATP

2 NADH

2 Pyruvate

Question 2

Insulin Regulation Effects

Answer 2

Increases number and activity of glucose transporters (GLUT)

Glucose can NOT diffuse directly into cell

NOT required for transport into liver cells

Question 3

General Hexokinase

Glucokinase

Answer 3

General Hexokinase:

Inhibited by G6P

Found in most tissues

Glucokinase:

Not inhibited by G6P

Liver

Question 4

Phosphofructokinase (PFK-1) Regulation

Answer 4

Up:

AMP

Fructose 2,6 Bisphosphate (Product of PFK-2)

Down:

ATP

Citrate

Low pH (H+)

Question 5

Enzyme for non-kinase phosphorylation in glycolysis?

Answer 5

Glyceraldehyde-3-phosphate dehydrogenase

Question 6

Key regulatory enzyme for glycolysis?

Answer 6

Pyruvate Kinase

Question 7

Pyruvate Kinase Regulation?

Answer 7

Up:

Fructose 1,6 Bisphosphate

Dephosphorylation (liver)

Down:

ATP

Phosphorylation (liver)

Question 8

ATP Producing Steps in Glycolysis

Answer 8

7 - Phosphoglycerate Kinase = + 1 ATP

10 - Pyruvate Kinase = + 1 ATP

Question 9

Anaerobic Fate of Pyruvate

Aerobic Fate of Pyruvate

Answer 9

Anaerobic: Ethanol, Lactic Acid (NOEL)

Aerobic: Acetyl-CoA

Question 10

What is source of galactose, how is it metabolized?

Answer 10

Product of lactose digestion, metabolized to Glucose-1-phosphate (G1P)

Question 11

Galactosemia

Answer 11

Defect in GALT

Enzyme build-up

G1P in Liver = Toxic

Galactitol build up = Cataracts, CNS damage

Question 12

Fructose Metabolism

Answer 12

• Faster than glucose metabolism; most dietary from sucrose BUT high fructose corn syrup present in many Western diets
• Converted in liver to Fructose-1-Phosphate (F1P)
• Cleaved by aldolase B
• End products can enter glycolytic pathways–bypasses PFK-1 regulation

Question 13

Problems with Fructose Metabolism?

Answer 13

• Activity of fructokinase > aldose B (F1P accumulation)
• F1P is allosteric regulator of several enzymes of carbohydrate metabolism–can lead to hypoglycemia, blocks glycolysis

- Can cause liver damage by blocking oxidative phosphorylation

- ADP/AMP can accumulate, high uric acid=GOUT

- Bypass of PFK-1 regulation = High lactic acid, high lipgenesis

Question 14

Aldolase B Deficiency

Fructokinase Deficiency

Answer 14

Aldolase B Deficiency - Fructose Intolerance

Fructokinase Deficiency - Essential Fructosuria

Question 15

Warburg Effect

Answer 15

Cancer cells carry out glycolysis at much higher rate than normal cells; foundation of PET scans