In a mouse-breeding experiment a new mutation called Dumbo is identified. A mouse with the Dumbo mutation has very large ears. It is produced by two parental mice with normal ear size. Based on this information, can you tell whether the Dumbo mutation is a regulatory mutation or a mutation of a protein-coding gene? Why or why not?

Key Concepts

Regulatory Mutations

Regulatory mutations occur in non-coding regions of DNA that control gene expression rather than altering the protein-coding sequence itself. These mutations can affect how much or when a gene is expressed, potentially leading to phenotypic changes without changing the protein structure. In the context of the Dumbo mutation, if the mutation affects the regulation of a gene involved in ear size, it could lead to larger ears without altering the protein-coding sequence.

Protein-Coding Genes

Protein-coding genes are segments of DNA that contain the instructions for synthesizing proteins, which perform various functions in the organism. Mutations in these genes can lead to changes in the protein's structure and function, potentially resulting in observable traits. If the Dumbo mutation were a change in a protein-coding gene, it would imply a direct alteration in the protein responsible for ear development, leading to the large ear phenotype.

Phenotypic Expression

Phenotypic expression refers to the observable traits or characteristics of an organism, which result from the interaction of its genotype with the environment. In this case, the Dumbo mutation leads to a distinct phenotype (large ears) that can arise from either regulatory changes or alterations in protein-coding genes. Understanding the source of this phenotypic change is crucial for determining the nature of the mutation.