This pathway is regulated by feedback inhibition at enzymes a through e. For parts a through e, list the intermediates and products shown which you might expect to be inhibitors of each enzyme. Explain your answer briefly. Lactose is a disaccharide found in milk. Although in the United States we are told that milk, it does a body good, many adults throughout the world get sick from drinking milk because they cannot digest lactose.
Lactose intolerance varies markedly among various human populations.
When someone who is lactose intolerant ingests milk, the lactose accumulates in the lumen of the small intestine because there is no mechanism for uptake of the disaccharide. This causes abdominal distension, cramping, and watery diarrhea. Adults who can drink milk can do so because of the enzyme lactase which is located on the outer surface of epithelial cells lining the small intestine. Lactase hydrolyzes lactose into its two component monosaccharides, glucose and galactose. Both glucose and galactose can cross the epithelial cells, and therefore do not cause illness.