11-6-08 review session for test 2

11-6-08 review session for test 2 - 349 Review Session for...

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349 11/6/08 Review Session for Test 2 3 signaling pathways that occurs during somite formation Hox genes: gives cell identity Delta notch: the timing, in chickens every 90 minutes you get somite form FGF and Retinoic Acid: allows FGF originates from the Henson’s Node which is the equivalence of the speaman organizer Henson’s node is migrating anterior to posterior and decreasing concentration of FGF in the posterior FGF prevents the presomatic mesoderm from differentiating If you decrease retinoic acid you get the same effect When you implant this FGF bead on the one side of the chicken *1* you will end up with this crooked chicken. Everything on one side will be shrunk Hox gene is not affected Heterochronic mutation in a gene is when you have a certain structure developing at the wrong time point Ex. Lin-14: L1 stage is skipped and goes to L2 Study Guide 1. correlation of delta notch causes expression of hairy gene ( hairy gene just show that the delta notch signaling pathway is indeed working Lunatic Fringe is a Golgi resident protein, has to do with modifying sugar residues *2*Notch gets cleave and goes into the nucleus as a transcription factor Now you get an increase in Lunatic Fringe expression If you have a mutation in delta notch you are disrupting the clock, either having small somite formation or large somite formation 2. Snakes have a ton more somites than the other organisms we’ve looked at; delta notch is conserved in snakes and instead of seeing it every 90 minutes you may see it every 15 or 20 minutes and has the same negative feedback loop 3. Not affected, chicken wrinkled up all on one side 4. Somite are determined very early in the presomatic mesoderm in fact *3* in the drawing in figure three we flip the presomatic mesoderm (pg 142) 5. (already went over) 6. Hox gene *4* genes that are closer to the 3’ portion they are expressed most anterior Antenepedia is the most anterior; abdominal B is the most abdominal (Remember increase by number and increase by alphabet) 7. On this one remember to go back to ultrabithorax For a loss of function you always have a duplication of the anterior function Antenepedia over expression in the wrong place i.e. ectopic which means wrong place or wrong time Applying to vertebrates… when you have a duplication of a hox gene you have a gain of a rib or something like that
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8. Differentiation of a somite *5* The region closest to the notochord will give rise to sclerotome which will be come cartiladge What factors affect this?
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This note was uploaded on 11/11/2009 for the course BIO Developmen taught by Professor Stevens during the Spring '09 term at University of Texas.

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11-6-08 review session for test 2 - 349 Review Session for...

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