Question

DNA sequences called homeoboxes help homeotic genes in animals direct development. Given that they are common to flies and mice, explain why these animals are so different.

Short answer

The non-homeobox sequences of homeotic genes determine how the homeotic gene products interact with other transcription factors and, therefore, which genes they control. Nonhomeobox sequences and homeobox gene expression patterns differ between the two species.

Step-by-step solution

Homeotic gene

In organisms such as echinoderms, mammals, insects, and fungi, homeotic genesplay an important role in development and growth. The phenotype of the organism is usually significantly altered by homeotic gene mutations. The mutation can cause displacement in the body parts of an organism.

Homeobox

Homeobox genes are important for ensuring cell identity and positioning during early embryonic development.Homeobox gene mutations can result in drastic developmental defects, such as the loss of a specific body part or segment or changes in its identity.

Transcription factor

The transcription process involves proteins that assist in the conversion of DNA into RNA. Transcription factors, with the exception of RNA polymerase, initiate and govern gene transcription. Transcription is the primary regulator of gene expression and controls genes.

Homeobox genes' purpose is the same—to make the head of a fly or tail for a mouse—making them general purpose genes. It is possible that changing these powerful regulatory genes or the genes triggered by them might lead to significant evolutionary changes.