Flight case lecture

Flight case lecture - Flight case lecture Evolution case...

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Flight case lecture Evolution case study Transition, emergence of flighted dinosaurs from non 0flighted dinosaurs Early dinosaurs showed characteristics of birds Cambrian explosion- diversification of complex body forms Basic body plans that we see in animal kingdom were set at that time, and elbaroation in plants Why this cam about? Hox genes that helped development, not coding for hemoglobin, but regulatory, telling other genes to turn or on off depending where they are in embro Fruit fly mutants Raise them quickly, reproduce quickly, see what genes do in phentotype Homeotic mutant Two wings, paired legs, halters for balance- normal paires, repeated pairs of appendages Hox genes- repeated appendages location Two pairs of wings, haltere gone- messed with hox genes Instead of antenaae, legs on head Telling genes to turn on or off Genes arranged and work as switches Place on chromosome in space relates in space on organism Front to back Actually sequence on genome, and follow on physical, hox genes which control head, abdomen, in order Follow path in space on genome More hox genes in rat embryo than fly gene More complicated the organism, more switches you need for more parts and complexity, One segment- one gene, if you have only one homebox gene, either on or off, legs or no legs, But if you start to get more genes, duplication event of hox gene, start to have independent mutations, once to start to get another, one gene can say legs or no legs, another genes- wings or no wings Different structures, and different patters, and more structure
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Cambrian explosion- set of switches for more complicated body plans The more you have these hox genes, more complicated organism See correspondence with changes in body plan and change in hox genes More diversity with limbs, and parts of the oddy, more homeobox genes Parsimony- fewest steps to evolution Cambrian explosion- beginning of phanerozoic
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This note was uploaded on 10/28/2010 for the course LS LS 1 taught by Professor Hespenheide during the Spring '07 term at UCLA.

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Flight case lecture - Flight case lecture Evolution case...

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