Question

In chapter 18, we have focused on large-scale as well as the inter- and intracellular events that take place during embryo-genesis and the formation of adult structures. In particular, we discussed how the adult body plan is laid down by a cascade of gene expression, and the role of cell–cell communication in development.

**How did we discover that selector genes specify which adult structures will be formed by body segments? What specific experiment can be connected to this discovery?

** How do we know that the eye formation in all animals is controlled by a binary switch gene?

Answer 1

** Homeotic genes are the selector genes which are present in the DNA in sequence in which these are expressed. The dicovery that selector genes specify which adult structure will be formed by body segment was done in drosophila. Scientists showed that certain genes are responsible for the transformation of organs and are the reason of evolution in the organisms. They worked on the drosophila mutants to look up for the genes that causes segmentation and formation of wings and limbs.

** Cells in the drosophila were studied and determined to monitor the genes which causes the formation of eyes. These were binary switch genes. Further studies on multiple organisms depicted the same theory.