Galactose Metabolism and Disorders

What is the primary function of galactokinase in galactose metabolism?

Which enzyme catalyzes the formation of UDP-galactose from galactose-1-phosphate?

What must happen to galactose-1-phosphate before it can enter the glycolytic pathway?

What is one potential outcome of UDP-galactose in metabolic pathways?

What is the fate of glucose-1-phosphate after being produced during the formation of UDP-galactose?

What enzyme is responsible for the conversion of UDP-Galactose to UDP-Glucose?

What is the primary cause of Galactosemia?

What mechanism leads to the symptoms of Galactosemia?

What dietary intervention is recommended for patients with Galactosemia?

What is the result of galactose accumulation in cells?

What condition is associated with cataracts in Galactosemia?

What is the outcome regarding mental retardation in Galactosemia treatment?

Which molecule is formed when galactose is reduced inside cells?

Galactose Metabolism

Galactose is derived from lactose (milk sugar)
Lactose hydrolysis by lactase produces glucose and galactose
Glucose enters glycolysis
Galactose is phosphorylated to galactose-1-phosphate by galactokinase, using ATP as a phosphate donor
Galactose-1-phosphate can't enter glycolysis. It needs to be converted to UDP-galactose.
This conversion occurs via an exchange reaction involving UMP, transferring from UDP-glucose to galactose-1-phosphate, resulting in UDP-galactose.
The enzyme that catalyzes this reaction is galactose-1-phosphate uridyl transferase.
UDP-galactose can enter various synthetic pathways for glycoproteins and lactose.
UDP-galactose also gets epimerized into UDP-glucose by UDP-galactose 4-epimerase.
Galactosemia results from defects in galactose metabolism pathways.

Specific Objectives

Students should be able to explain the metabolic pathway of galactose.
Students should be able to discuss disorders in galactose metabolism.

Galactokinase Deficiency

Rare autosomal recessive disorder
Causes elevated galactose and galactosuria
Galactitol accumulation can cause cataracts
Treatment involves dietary restrictions.

Classic Galactosemia

Autosomal recessive disorder (1 in 30,000 births)
Deficiency in galactose-1-phosphate uridyltransferase (GALT)
Accumulation of galactose-1-phosphate and galactitol in tissues like the liver, nerves, and lenses
Leads to liver damage, developmental delays, cataracts, and mental retardation.
Prenatal diagnosis and newborn screening are available.
Treatment involves a galactose-free diet.

Cataracts in Galactosemia

Occurs due to galactose accumulation, converting to galactitol in cells, causing osmotic swelling.
The accumulation of galactose inside cells results in the formation of cataracts.

This quiz focuses on the metabolic pathways involved in galactose metabolism, derived from lactose. It covers the enzymatic processes, conversions to UDP-galactose, and associated disorders like galactosemia. Students will deepen their understanding of how galactose is processed within the body.