Part 3- August 2, 2013: Ch 7-9

What did you think about the reading?

 I enjoyed the many questions that Shubin arose throughout these chapters, As well as the experiment he mentions at the beginning. It makes the proceeding information very intriguing. I also have started to enjoy his simple, yet to the point, style of writing, making it an entertaining book to read.


What did you learn?

 I learned that sponges can be divided and they can come back together and continue functioning as before. They are primitive. Also, that choanoflagellates are close relatives to sponges. These contain similar genes that are present in animals coding for the creation of a body. Dr. Shubin discusses about the differentiation between the cells in our nose to those of another location in the body. He suggests that some fish have two scent receptors, verifying fish, once again, as a common ancestor. Shubin also informs the reader that some scent receptors and genes on certain animals, like whales, have been silenced, due to disuse and dysfunctionality. Through various experiments and discoveries, it was found that jawless fish have neither land nor water genes, but a combination, which shows that they existed before the genes for smell split. I learned that humans have also lost many scent genes through mutations.  In continuity, I was reminded that opsin acts like light-capturing molecule that relay signals to the brain to create an image. Also it is discussed that when a more colorful habitat evolved, the evolution of a third receptor in the eye allowed for a more colorful vision in some organisms. Lastly, I found the Pax6 gene intriguing as Dr. Shubin describes how it can be transferred from one animal to another (to any desired part of the organism’s body), while retaining its eye forming function.


What questions do you still have?

Could the Pax6 gene be used in humans for eye repair? Or to aid the blind?

If humans have risen from the grouping of cells to fight predators, then why do they not continuously arise in that same format?

What were those cells before they grouped? What composed them?



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