Technology associated with biology has advanced throughout the years, which has allowed the current classification system to be enhanced by using genetic analysis of DNA sequences.
Originally Linnaeus' system relied purely on human judgement in order to compare the characteristics of various organisms. Now the comparisons of DNA sequences have allowed the relationship of organisms to be explored further. In some cases, species that are more closely related may have fewer differences contained within the DNA sequences. DNA sequences are shown as the order of DNA bases, abbreviated as A, C, G and T.
There has been debate in history over the classification of the red panda and the giant panda. Some argued that they should belong to the bear family and others argued that they are more like racoons. Following the development of DNA sequencing technology, it has been shown that the red panda and ginat panda are not very closley related genetically. DNA analysis showed the giant panda to be a bear, and the red panda to be more closely related to a racoon.
Classification systems have continued to be developed by other scientists, such as Carl Woese who developed the three-domain system. This is based on evidence genetic analysis.
Genes of an organism code for proteins. It has been demonstrated that some organisms have parts of their genes that are not used in making proteins and other organisms that use entire genes to code for proteins, with no unused portions. This information has informed the three-domain system.
The updated system divides organisms into:
|Archaea (primitive bacteria)||These cells usually live in extreme environments. They have no nucleus and have unused sections of genes.|
|Bacteria (true bacteria)||Bacteria cells have no nucleus and no unused sections of genes.|
|Eukaryota (including protists, fungi, plants and animals)||These have a nucleus and have unused sections of genes.|