Biology 2581B Study Guide - Quiz Guide: Homeosis, Homeotic Selector Gene, Imaginal Disc
1 Jun 2020
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Document Summary
One common characteristic between complex body plans is that they are modular - made from smaller segmental units. Throughout evolution this has been an advantage because segments can be modified, added and taken away. In the human body, ribs, vertebrae and hands are all made of repeated modular structures. There are differences between vertebrae but they all display homology. This means they all have a similar morphology (shape) Just after gastrulation, somites either side of the neural tube contribute to the segmented structure. Each somite will give rise to a vertebrae, among other structures. Rhombomeres in the hindbrain have a very segmental pattern also. The drosophila embryo gets to a point where it has lots of segments but these have not yet been given instructions on what to become. This is when the gene ultrabithorax (ubx) gives segments positional information to make them form specific structures.
