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?

Verified step by step guidance

1. <span>Understand the concept of homeotic mutations: Homeotic mutations are changes in genes that lead to the transformation of one body part into another. These mutations often affect genes that control the development of body segments.</span>
2. <span>Identify the nature of the Antennapedia mutation: Antennapedia is a dominant gain-of-function mutation, meaning that a single copy of the mutated gene is sufficient to cause the phenotype, and the mutation results in a new or enhanced function of the gene product.</span>
3. <span>Explore the role of the Antennapedia gene: The Antennapedia gene is part of the Hox gene family, which plays a crucial role in determining the identity of body segments along the anterior-posterior axis in Drosophila and other organisms.</span>
4. <span>Examine how the mutation affects gene expression: In the case of Antennapedia, the mutation causes the gene to be expressed in the head region where it is not normally active, leading to the development of legs instead of antennae.</span>
5. <span>Consider the molecular mechanism: The gain-of-function mutation in Antennapedia likely alters the regulatory elements of the gene, causing misexpression in the head region, which results in the transformation of antennae into legs.</span>

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.