Question
Early specification during this process is mainly controlled by Islet1, Pitx1 (“Pit-X-1”), Tbx4, and Tbx5. For 10 points each:
[10h] Name or describe this process that occurs in the progress zone. In one model, “patterning” in this process is induced by opposing FGF and Wnt (“wint”) gradients from the distal AER (“A-E-R”) and a second retinoic acid gradient from the proximal flank.
ANSWER: limb development [or limb formation; accept legs or foot or feet or arms or fins or flippers or wings in place of limbs; accept descriptions indicating that the formation of limbs]
[10m] During limb development, the zone of polarizing activity regulates digit formation by generating a gradient of this protein. Drosophila embryos holding a mutation for this protein often display a “spiky-ball” phenotype.
ANSWER: Sonic hedgehog protein [or Shh; prompt on hedgehog protein or hh]
[10e] Sonic hedgehog’s role in limb development was discovered by John Saunders, who used this bird as a model organism. This bird names a pox disease whose causative agent also causes shingles.
ANSWER: chicken [or Gallus gallus domesticus; accept chicks; accept hens; accept cocks; accept chickenpox]
<Kane Nguyen, Biology>
Summary
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