BIOLOGY 1A03 Study Guide - Final Guide: Lactose Intolerance, Mcm6, Fermented Milk Products

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

Document Summary

Lactose : a sugar common in milk and other dairy products. Can serve as a primary energy source. Lactase breaks down lactose for absorbance to metabolize in the body. Glucose and galactose are absorbed at enterocytes (simple columnar epithelial cells): Lactase (a -galactosidase) hydrolyzes lactose to the monosaccharides glucose and galactose. Present on apical (top) surface of absorptive intestinal enterocyte cells. Lactase production generally decreases after weaning: in adult mammals other than humans, lactase production decreases significantly after weaning. ~65% of humans have reduced ability to digest lactose after weaning (being fed breast milk by mother?) weaning. This means that the gene is turned on less. Mutation that keep the lactase gene permanently on: Common in individuals whose ancestors had access to domesticated dairy animals (inherited as a dominant trait) Cows domesticated between 7500-9000 years ago in middle east and north africa, then brought to europe. Consumed a lot of milk if domesticated cows.