CHAPTER 3:: HANDY GENES

Q.  Describe the hedgehog gene using animal examples.


- This chapter mainly concentrates on how the genome of all living organisms are similar to a great extent. Thus altering the genome of a particular species with a similar gene from another species can produce an entirely diffreent result. The author's lab can be divided into two different parts; the study of fossils and the study of DNA along with embryonic development. A number of chemicals secreted by our cells help develop our body. All of the genetic switches that control this occur between the third and eighth week after conception.

- Limb development is the core topic of this chapter. It was discovered in the 50's-60's that a certain patch of cells control limb development. If such a patch was to be removed, limb development would not occur. If it was turned over, limb devloment would occur backwards and if it was cut in half, there would be two limbs present instead of one (this was performed in chickens).

- In flies this gene was known as hedgehog, and in chickens it was known as sonic hedgehog. It was noticed that Vitamin A activates thesonic hedgehog. When this gene (extracted froma mouse) was injected into a shark, the limb development was affected in the same way as when the Vitamin A was injected. This meant that the protein and therefore the gene were effectively the same in a shark and a mouse.