BIL 160 Lecture Notes - Lecture 8: Hox Gene, Deuterostome, Protostome
28 Apr 2016
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Document Summary
Sometimes changing how a gene is expressed can change everything: timing, more or less of the gene. Transcription factor: protein that binds to a specific dna sequence and continues how that segment of dna is read. All enhancers have proteins attached= active gene translation. Repressors: stops it: can be increased, decreased, or shut off. Early development: zygote- cleaves, genes turn on and off, transcription control is positive (activator is stuck on operator) or negative (repressor is stuck on operator, specialized cells= organs, tissues, programed to die (apoptosis, genetic toolkit (hox genes) Hox genes determine identity of body segments in all organisms. Protostome vs deuterostome= reversed in body position: protostome (worm, mollusks) Intestine= ventral: but genes of both are still homologous. Gene expression: beaks in finches, scales, feathers etc. (placodes) Unrelated lineages towards a similar or parallel form= convergent evolution: placental mammals vs. marsupials.
