Carbohydrate Metabolism- Fructose & Galactose

Question 1

What does the disaccharide Sucrose breakdown to and how? (Hint: “SF”, California)

Answer 1

There is an amylase enzyme called SUCRASE that breaks sucrose–> fructose + glucose

Question 2

What does the disaccharide Lactose breakdown to and how? (Hint: “LG”)

Answer 2

The disaccharide lactose breaks down into via LACTASE; galactose + glucose.

Question 3

How is Fructose uptaken into the cell from intestinal lumen?**

Answer 3

GLUT 5; a new GLUT transporter enzyme that I JUST LEARNED ABOUT LOL.

Question 4

How is Galactose and Glucose taken into the cell from intestinal lumen?***

Answer 4

Na+/glucose transporter 1 (SGLT 1)**

Question 5

What is Fanconi-Bickel Syndrome? Pathology?

Answer 5

Fanconi-Bickel Syndrome is a syndrome in which the GLUT 2 transporters (liver, kidney, GI cells) can’t absorb the glucose, fructose, and galactose.

sx: Hepatomegaly, tubular nephropathy, abdominal bloating (bacteria are feasting lol), inability to thrive
tx: vitamin D + phosphate

Question 6

What is the polyol pathaway? (fructose anabolism)

Answer 6

The polyol pathway is a pathway that converts glucose–> sorbital–> fructose

glucose–> sorbitol (aldose reductase)
sorbitol–> fructose (sorbitol dehydrogenase)

Question 7

What happens when cells lack sorbitol dehydrogenase?

Answer 7

Sx: peripheral neuropathy, cataracts (swelling of cells)

Question 8

Why is fructose corn syrup so bad for you? (fructose catabolism)

Answer 8

The fructose catabolism mechanism bypasses regulatory steps like PFK to F16BP and because of this you will more easily store fat because there is nothing regulating the feeding of G3P or DHAP into Aerobic Respiration.

Question 9

What is galactosemia? How does it occur?

Answer 9

Galactosemia is a disorder in which GALT enzyme and Galactokinase is both affected.

Cause: Can’t convert Galactose–> glucose

sx: failure to thrive, liver failure, sepsis, bleeding