BIO 10 - Biology Lab; Tuesday: 15:00 hours to 17:50 hours
TAXOMONY LAB - Classification of Living Things.
Taxonomy (from Greek taxis meaning arrangement or division and nomos meaning law) is the science of classification according to a pre-determined system, with the resulting catalog used to provide a conceptual framework for discussion, analysis, or information retrieval. In theory, the development of a good taxonomy takes into account the importance of separating elements of a group (taxon) into subgroups (taxa) that are mutually exclusive, unambiguous, and taken together, include all possibilities. In practice, a good taxonomy should be simple, easy to remember, and easy to use.
One of the best known taxonomies is the one devised by the Swedish scientist, Carl Linnaeus, whose classification for biology is still widely used (with modifications).
Today's classification is based mostly on similarities in structure and evolutionary relationships.
Remembering the division of the animal kingdom:
kingdom, phylum, class, order, family, genus, species
King Paul called out for Gus and Sam,
or
King Philip Cuts Open Five Green Snakes
Kingdom, Phylum, Class, Order, Family, Genus, Species
The Three Domain System, proposed by Woese and others, is an evolutionary model of classification based on differences in the sequences of nucleotides in the cell's ribosomal RNAs (rRNA), as well as the cell's membrane lipid structure and its sensitivity to antibiotics. Comparing rRNA structure is especially useful. Because rRNA molecules throughout nature carry out the same function, their structure changes very little over time. Therefore similarities and dissimilarities in rRNA nucleotide sequence are a good indication of how related or unrelated different cells and organisms are. This system proposes that a common ancestor cell ("Cenancestor") gave rise to three different cell types, each representing a domain. The three domains are the Archaea (archaebacteria), the Bacteria (eubacteria), and the Eukarya (eukaryotes). The Eukarya are then divided into 4 kingdoms: Protists, Fungi, Anamalia, and Plantae.
Five Kingdom Classification System
Most biologists recognize five kingdoms: Monera (the prokaryotes); Protista (the single-celled eukaryotes); Fungi (fungus and related organisms); Plantae (the plants); and Animalia (the animals). Accepted systems of classification have changed at a far faster pace than the species have taken to evolve.
The kingdoms are divided into categories called phyla, each phylum is divided into classes, each class into orders, each order into families, each family into genera, and each genus into species. A species represents one type of organism, such as dog, tiger shark, Ameoba proteus (the common amoeba), Homo sapiens (us), or Acer palmatum (Japanese maple). Note that species names are always underlined or written in italics.
1. Taxonomy works out for us a vivid picture of the existing organic diversity of the earth.
2. Taxonomy provides much of the information permitting a reconstruction of the phylogeny of life.
