Common ancestry- Addison

     Studying the genetic code of organisms give biologists an idea of common ancestors among organisms. Mammals all have very similar genetic codes and only have a little bit of variance in amino acid sequence that changes their species. This may hint that we all derived from the same species. For example, scientists are able to compare the different bone structures that are similar in different species, and see where other species may have diverged from. Humans have a tailbone, but we do not have a tail. This suggests that we share ancestry with organisms who have a tail, and may have derived from a species that had one. This is because our genetic code is so similar to other mammals who have a tail.

    Membrane bound organelles are also a hint at common ancestors. There is evidence to suggest that mitochondria once was actually a prokaryotic bacterial cell. And over time it worked with and engulfed another to have one organism inside of another. This shows that the common ancestor of mitochondria and other membrane bound organelles are prokaryotes. Over time these different organisms worked together called endosymbiotic theory, and created the membrane organelles that now work in our body.

   All bacterial cells have circular chromosomes, while eukaryotic cells have linear chromosomes. This, again suggests a common ancestry among all prokaryotic organisms and al eukaryotic organisms. Because all prokaryotes have circular chromosomes, we can assume that one prokaryotes had this and passed it on for many generations. The same can be said for eukaryotes. All eukaryotic cells have linear chromosomes, and not circular. This is another reason why eukaryotic organisms are more similar gat prokaryotic ones. Prokaryotes cannot have the linear chromosomes because they did not derive from eukaryotes.