BIOL 2400 Chapter Notes - Chapter 10.3: Neurogenic Placodes, Symmetry In Biology, Gene Duplication
5 Dec 2013
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Document Summary
Hox genes and other so-called patterning genes participate in regulatory networks that demarcate the geography of developing animals, determining the relative locations and sizes of body parts. These networks comprise an ancient genetic toolkit inherited by all animals with bilateral body symmetry. Mads-box genes and knox genes comprise an analogous (but unrelated) genetic toolkit in plants. Orthologs homologous genes separated by a speciation event (as opposed to paralogs, homologous genes produced by gene duplication that are both processed by the same species) Blocking or interrupting the expression of a patterning pathway can result in complete loss of a structure. Sometimes subtle changes in the levels of expression of developmental genes can dramatically alter phenotypes. Truncate or block pathway mutation block growth of all or part of limb. Change signal levels of elements within pathway mutation change shape or proportion of structure. Deploy in new body region form new outgrowth.
