9.3 Other Monosaccharides

Question 1

What is an important source of galactose in the diet?

Answer 1

• Lactose, a disaccharide
• Lactase hydrolyzes lactose to galactose and glucose

Question 2

Lactase

Answer 2

• Brush-border enzyme of the duodenum

Question 3

How does galactose reach the liver?

Answer 3

through the hepatic portal
vein

Question 4

Epimerases

Answer 4

• enzymes that catalyze
  the conversion of one sugar epimer to another
• epimers are diastereomers that differ at exactly one chiral carbon

Question 5

What is the pathway for galactose metabolism?

Answer 5

Galactose + Galactokinase -> Galactose 1-Phosphate + Galactose-1-phosphate uridyltransferase -> Glucose 1-Phosphate

Question 6

Fructose

Answer 6

found in honey and fruit and as part of the disaccharide sucrose (common table sugar)

Question 7

What is Fructose metabolism pathway?

Answer 7

Sucrose + Sucrase (enzyme) -> glucose + fructose -> (takes hepatic portal) Liver + Fructokinase -> Fructose 1-P