Introduction The Rock Pocket Mouse The rock pocket mouse, Chaetodipus intermedius, is a small, nocturnal animal found in the deserts of the southwestern United States. Most rock pocket mice have a sandy, light-colored coat that enables them to blend in with the light color of the desert rocks and sand on which they live. However, populations of primarily dark- colored rock pocket mice have been found living in areas where the ground is covered in a dark rock called basalt caused by geologic lava flows thousands of years ago. Scientists have collected data from a population of primarily dark-colored mice living in an area of basalt called the Pinacate lava flow in Arizona, as well as from a nearby light-colored population. Researchers analyzed the data from these two populations in search of the genetic mutation responsible for the dark coat color. Their analyses led to the discovery of a mutation in the Mc1r gene that is involved in coat-color determination. The MC1R Gene Two pigments primarily determine the coat color of rock pocket mice: eumelanin, which is dark-colored, and pheomelanin, which is light-colored. The products of several genes, including the Mc1r gene, control the synthesis of these pigments. This gene encodes a protein called the melanocortin 1 receptor (MC1R) and is found embedded in the cell membranes of melanocytes, specialized pigment-producing skin cells. The melanocytes of wild-type (nonmutant) mice produce more pheomelanin than eumelanin. The result is a sandy- colored mouse. The mutated version of the Mc1r gene, however, triggers melanocytes to increase the production of eumelanin, resulting in the dark coat-color phenotype. Question: Using the information provided in the introduction, explain in your own words how the mutation to the protein affects the color of the mouse’s coat.
Introduction
The Rock Pocket Mouse
The rock pocket mouse, Chaetodipus intermedius, is a small, nocturnal animal found in the deserts of the
southwestern United States. Most rock pocket mice have a sandy, light-colored coat that enables them to blend
in with the light color of the desert rocks and sand on which they live. However, populations of primarily dark-
colored rock pocket mice have been found living in areas where the ground is covered in a dark rock called
basalt caused by geologic lava flows thousands of years ago. Scientists have collected data from a population of
primarily dark-colored mice living in an area of basalt called the Pinacate lava flow in Arizona, as well as from a
nearby light-colored population. Researchers analyzed the data from these two populations in search of the
genetic mutation responsible for the dark coat color. Their analyses led to the discovery of a mutation in the
Mc1r gene that is involved in coat-color determination.
The MC1R Gene
Two pigments primarily determine the coat color of rock pocket mice: eumelanin, which is dark-colored, and
pheomelanin, which is light-colored. The products of several genes, including the Mc1r gene, control the
synthesis of these pigments. This gene encodes a protein called the melanocortin 1 receptor (MC1R) and is
found embedded in the cell membranes of melanocytes, specialized pigment-producing skin cells. The
melanocytes of wild-type (nonmutant) mice produce more pheomelanin than eumelanin. The result is a sandy-
colored mouse. The mutated version of the Mc1r gene, however, triggers melanocytes to increase the
production of eumelanin, resulting in the dark coat-color
Question: Using the information provided in the introduction, explain in your own words how the mutation to the protein affects the color of the mouse’s coat.
Trending now
This is a popular solution!
Step by step
Solved in 3 steps
