BIOLOGY 1A03 Study Guide - Midterm Guide: Lactose Intolerance, Lactase, Galactose

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

Document Summary

Bio 1a03 applied lectures themes 3 and 4. Lactose: a common sugar found in milk and other dairy products; can serve as a primary energy source. Lactase: a type of b-galactosidase that breaks lactose down into glucose and galactose. Enterocyte cell: lines the microvilli in the intestines. Lactase is present on the apical surface of intestinal microvilli. Lactase is not present in the large intestine. Galactose: is not a fuel source and needs to be further broken down. Gal-1-p uridyltransferase: swaps galactose phosphate for glucose phosphate. Lactase production generally decreases to baseline after weaning for all other mammals. 65% of humans have reduced ability to digest lactose after weaning. Mutations have caused the lactase gene to remain permanently on. Common in individuals whose ancestors had access to domesticated dairy animals (dominant trait) Cows domesticated between 7500-9000 years ago in middle east and north africa, then brought to europe.