Your Inner Fish Chap 6 Discussion

     Shubin talks about the best-laid body plans, development from the embryo, germ layers, and the control of DNA. He explains that a scientist named Karl Ernst von Baer discovered that organs are derived from 3 developing layers in the embryo which are the ectoderm, endoderm, and mesoderm. Every animal got their organs from these three germ layers. He also talks about discoveries where the embryo splits and causes twins. I learned that the Organizer is a small piece of tissue that causes the cells in the embryo to make a body plan. All mammals, birds, amphibians and fish contain an Organizer. This links back to evolution and a common ancestor. He then gives diagrams and explanations that show that humans and flies contain Hox genes which are Organizers that are involved in the development of the body plan. DNA controls the Organizer. He finally mentions Noggin which is a gene that can grow back structures and even a second head for frogs when injected into an egg. I learned that DNA mutations and manipulation in the embryonic stages can affect the appearance and structure of an organism.