The homeotic mutation Antennapedia causes mutant Drosophila to have legs in place of antennae and is a dominant gain-of-function mutation. What are the properties of such mutations? How does the Antennapedia gene change antennae into legs?

Key Concepts

Homeotic Genes

Homeotic genes are crucial for determining the identity of body segments in organisms. They encode transcription factors that regulate the expression of other genes, guiding the development of specific structures. In Drosophila, mutations in these genes can lead to dramatic changes in morphology, such as the transformation of antennae into legs, as seen in the Antennapedia mutation.

Gain-of-Function Mutations

Gain-of-function mutations result in a gene product with enhanced or new functions. In the case of Antennapedia, this mutation causes the gene to be expressed inappropriately, leading to the development of legs instead of antennae. Such mutations can provide insights into gene regulation and developmental pathways, often resulting in dominant phenotypes.

Gene Regulation and Development

Gene regulation is the process by which cells control the expression of genes, influencing development and cellular function. In Drosophila, the spatial and temporal expression of homeotic genes is tightly regulated to ensure proper segment identity. The Antennapedia mutation disrupts this regulation, causing misexpression that alters the developmental fate of antennae into legs.