BIOL 2P05 Lecture Notes - Lecture 23: Embryonic Stem Cell, Allometry, Gene Duplication
14 Mar 2018
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Document Summary
Homeotic genes (hox and mads-box) encode transcription factor proteins that guide development. Once bound to enhancer, it turns transcription on. Multiple enhancers for one gene responsible for different phenotypes. Multiple copies of may affect the dosage of mrna transcribed. One of the many duplicates may accumulate non-functional mutations. Duplication and divergence allowed hox genes to take different jobs. Increase in the number of hox genes may be partially responsible for diversity/complexity of body plan. Different types of changes related to hox genes: of hox genes, changes in expression of hox genes (location/time, changes within hox domains, changes in regulation of downstream genes. Production of legs was restricted to thorax and head. Head shaped for sensory input, ingestion of food, and elaboration of cns. Case study: changing a worm into a fly. Group of embryonic stem cells controlled by homeotic genes. Initially positioned near the neural tube during early development and then migrate to new locations during embryological stages.
