Question

In humans, typically only infants produce the enzyme lactase to break down lactose. Some adults have changes in _____ that allow transcription factors to bind and turn on expression of the lactase gene into adulthood?

Answer 1

Some adults can produce the enzyme lactase into adulthood due to changes in regulatory DNA sequences, preventing lactose intolerance and allowing them to digest milk. This genetic variation can give an evolutionary advantage in populations where dairy products are a significant part of the diet.

Step-by-step explanation:

In humans, typically only infants produce the enzyme lactase to break down lactose. Some adults have changes in regulatory DNA sequences that allow transcription factors to bind and turn on expression of the lactase gene into adulthood. This genetic variation enables the continued production of lactase, which is necessary for the digestion of lactose, the sugar found in milk. People without these changes typically produce less lactase as they grow older, leading to a common condition known as lactose intolerance.

Lactose intolerance means that the individual cannot effectively digest lactose due to a deficiency in lactase. This condition can lead to symptoms such as bloating, diarrhea, and abdominal discomfort after consuming dairy products. In contrast, those who maintain the ability to produce lactase can digest lactose without issue. The persistence of lactase production in some adults is thought to have had evolutionary benefits, particularly in populations where dairy farming was prevalent, allowing for improved digestion and nutrition from dairy products.