BIOLOGY 1A03 Lecture Notes - Lecture 11: Lactose Intolerance, Lactase, Mcm6

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Alastair Tracey Rosa Da Silva

Document Summary

Lactose sugar common in milk and other dairy products. Can serve as a primary energy source. Lactase ( -galactosidase) hydrolyzes lactose to the monosaccharides glucose and galactose. Present on apical surface of absorptive intestinal enterocyte cells. Glucose and galactose can be transported to the body. Rat microvilli image fluorescent antibodies are specific to lactase shines red to show were lactase is. Lactase is on the peripheral membranes of microvilli lining the membrane. Lactose to glucose goes through glycolysis and pyruvate processing. Lactose to galactose converted to glucose first* Galactokinase binds to galactose (add phosphate groups to proteins) Adult mammals other than humans, lactose production decreases significantly after weaning. ~65% of humans have reduced ability to digest lactose after weaning. Lactase enzyme activity in rabbits" peaks around 15 days highest number of enzymes being expressed. As diet changes, lactase enzyme activity in blood have decreased. Mutations that keep the lactose gene permanently on.