Fossils Chapter Summary

Fossils are a large part of discovering about the past, but to understand how fossils change over time, genes also need to be investigated. These investigations are just as important as the fossils, because of how DNA can be tested through the use of embryos. During Shubin’s expeditions into the Artic, one researcher, Randy Dahn, was experimenting with the embryos of sharks and skates. He would use various chemicals on the embryos, and examine the results to see what changes that the chemicals would make on the structural developement, and DNA of the embryos. When examining the DNA of embryos and how it changes the shape of cells and functions of cells, the genes of that cells DNA are what need to be examined. Only by studying the individual genes and when they are activated or deactivated, can scientists understand there specific function, and how the chemicals applied to embryos affects their growth. When looking at a standard embryo’s DNA, scientists can compare it to the DNA of other embryo specimens to determine which genes are possibly controlling certain developements in the embryo. The examples Shubin gives for …show more content…
1. In the 1950’s, and the 1960’s the biologist Edgar Zwilling experimented on chicken embryos by cutting small pieces off of the bird, and either keeping them removed, or moving the piece to another part of the embryo. One experiment took off the tip of the embryos developing wing, which completely stopped the wing from forming. This discovery was the discovery of the ZPA, which led to the discovery of the hedgehog gene, which allowed scientists to discover the gene in all developing animals.
2. The Hedgehog gene is a gene found in the center of flies. It was named the Hedgehog gene due to its resemblance to a hedgehog, and is used to determine which side will be the front of the fly, and which side will be the back of the