We talked about the genes controlling our ability to digestlactose, the sugar found in milk. Collectively the enzymes producedby the set of genes involved are called lactase. \"Lactoseintolerance\" describes the most common condition in human adults,which is an inability to digest lactose because lactase is notproduced. These people could all produce lactase as infants,however, so they have the genes needed to produce functionalenzymes. Somehow the regulation of expression of the genes changesas most people grow up.
People who can digest lactose as adults are said to be \"lactasepersistent\", that is, they continue to produce lactase even inadulthood. Ponder the genetic mechanisms for regulating theexpression of the genes producing lactase and describe threefeasible hypotheses for mutations affecting the regulatingmechanisms that would enable a person to produce lactase as anadult.
