Mastering Biology HHMI: Got Lactase?

Which discovery supports the hypothesis that evolution of the lactase-persistence trait was driven by the use of milk in pastoralist cultures?

Ancient pots used to hold milk are about the same age as the lactase-persistence mutation

Suppose that a mutation for lactase-persistence occurred in each of the populations described below. In which populations would the mutation be more likely to increase in frequency over time because of natural selection?

a population that raises wheat and sheep

The enzyme lactase breaks the sugar lactose into which compound(s)?

Galactose Glucose

How does the term "lactase persistent" relate to the term "lactose tolerant"?

A lactase-persistent person is lactose tolerant.

What did researchers discover about the genetic mutation causing lactase persistence?

It is found in a regulatory region (a "switch") upstream of the lactase gene

How could milk-drinking have provided strong favorable selection for lactase persistence?

Milk may have been a critical food source during times of famine. Milk is protein and fat-rich and therefore could have been an important, high-quality food source. Milk was safer to drink than water and reduced exposure to pathogens

Four individuals measured their baseline blood glucose, then drank a litre of milk. They then measured their blood glucose levels at regular 15 minute intervals for 60 minutes. The results are shown in the graph below. Which individuals are lactase-persistent?

Sarah Peter