Passing on Mutations

Question

Mutations occur when the DNA sequence of an organism changes. Mutations can be inherited or the result of environmental factors. Mutations can result in a structural or functional change for organisms. Mutations can affect how an organism looks and how body systems function. This is due to a change in the DNA that affects the organism's proteins, which in turn, affects an organism's traits.

The changes that occur from mutations can have a beneficial, harmful, or neutral effect on an organism.

Sometimes, the changes are beneficial. For example, a bacterium has a mutation that makes it resistant to antibiotics.
Sometimes, the changes are harmful. For example, an albino tree frog has difficulty blending into its environment.
Sometimes, the changes are neutral. For example, a mutation can cause rose petals to change color.
A mutation can cause a normal red blood cell to have a sickled shape. A model of the mutation is shown.



Constructed Response Question
A rock pocket mouse typically has light-colored fur that helps it blend in to its environment and avoid predators. In a desert location, a population of rock pocket mice experienced a mutation that resulted in a change in fur color. Originally, the fur color of the mice in the population was light, similar to the color of the surrounding desert. A lava flow occurred in the area, resulting in dark, rocky areas. A mutation to the Mc1r gene, the gene responsible for pigment production, caused some of the mice to be born with dark fur. Over each generation, a greater percentage of the mice in the population were born with dark fur. Today, most of the rock-pocket mice that live in dark, rocky areas have dark fur.

Identify if the Mc1r gene mutation is beneficial, harmful, or neutral. Provide an explanation.

​

Answer 1

The mutation in the Mc1r gene that causes dark fur in rock pocket mice can be classified as beneficial.

Explanation: In the context of their environment, the mutation that results in dark fur enhances the survival of these mice. The dark fur allows them to blend in with the rocky areas created by a lava flow, providing better camouflage against predators compared to their originally light-colored fur. This improved ability to avoid detection by predators increases their chances of survival and reproduction. Over generations, as more mice with the beneficial dark fur survive and reproduce, the trait becomes more prevalent in the population, demonstrating natural selection in action. Therefore, this mutation is advantageous in the given environmental context, making it beneficial.