A. Biological Filekeeping: An Overview
1. The Current System: A Definition
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fgfgfgf Taxonomy is the theory and practice of classifying organisms. Biological classification systems are important for several reasons. The similarities and differences of organisms falling into the same groups are invaluable to study because:

fgfgffgf They improve our ability to explain relationships among organisms.
gfg They are a memory aid for the characteristics of organisms.
ghgfgfghh They are useful as predictors of the components of organisms.

dfddfdffPhylogeny expresses the evolutionary history of a particular group of organisms through a family tree. Common ancestral relationships that species share is the basis for classification used around the world today. Because any given group of organisms can only share a single common ancestor, this system provides an adequately discriminating language for biologists to use throughout the world.

2. Back in the Good Old Days: Historical Origins
dfdfdfdfPrior to 1735, when biologists studied an organism that they believed to be new to the scientific community, they were given the freedom to assign their own scientific name. As is expected, the descriptions became complicated as well as useless when many scientists assigned one species the same name.

Carolus Linnaeus: The Father of Taxonomy
ghghghFresh from medical school and continuing his education at the University of Leiden in the Netherlands, Linnaeus published the Systema Naturae, the first edition of his classification of living things, in 1735. During the years that followed, he met or corresponded with Europe's great botanists, and continued to develop his classification scheme.

B. Specific Class Fields

1. The Definition and Scope of Classification Categories:
ghA crash course in biological file-keeping!
dfKKK-Directions: Please follow the major headings below as they will trace organism categories from most broad to most specific.-

The Biosphere: Life on Earth
dfdfdfLife! It's everywhere on Earth; you can find living organisms from the poles to the equator, from the bottom of the sea to several miles in the air, from freezing waters to dry valleys to undersea thermal vents to groundwater thousands of feet below the Earth's surface. Over the last 3.7 billion years or so, living organisms on the Earth have diversified and adapted to almost every environment imaginable. The diversity of life is truly amazing, but all living organisms do share certain similarities (Waggoner, Intro).

Three Domains of Life
jkjkjkUntil comparatively recently, living organisms were divided into two kingdoms: animal and vegetable, or the Animalia and the Plantae. Recent work, however, has shown that what were once called "prokaryotes" are far more diverse than anyone had suspected. The Prokaryotae are now divided into two domains, the Bacteria and the Archaea, as different from each other as either is from the Eukaryota, or eukaryotes.
dfdfdfdfTrypanosome's Home: Eukaryota

Kingdoms of Life
dfdfdfdThis it the largest unit of classification. Initially it was thought that there were only two kingdoms, plants and animals. Eventually microscope and other tools helped clarify the existence of other organisms. Now, there are a total of 5 kingdoms. Animalia - the largest with over 1 million named species, fish, humans; Plantae - 350,000 species, trees, grass; Fungi - 100,000 species, mushrooms, lichen; Protista - 100,000 species, green, golden, brown, and red algae, flagellates; Monera - 10,000 species, blue-green algae or cyanobacteria.
dfdfdfdfTrypanosome's Home: Protista

Phylum
dfdfdf The next most specific unit of classification. This further divides the kingdom into 20 or so divisions based on very distinct and defining characteristics. For example, within the Animal Kingdom, a major division is the chordates that are animals with notochords. This includes humans, fish, mammals, etc.
dfdfdfdfTrypanosome's Home: Euglenozoa
The euglenozoa are a small group of unicellular algae, comprising about 1,600 species. Characteristic of the euglenozoa are disklike mitochondrial cristae, cortical microtubules under the outer layer of the plasma membrane, and paraflagellar rods.

Class
kjkjkjk This further classifies the organism. It separates them into categories that make them very similar in terms of certain basic features. For example the class mammalia includes all animals that breast-feed, which includes humans, cows, dolphins, etc. Another class would be reptilia which includes cold-blooded and scaled animals.
dfdfdfdfTrypanosome's Home: Zoomastigophorea

Order
dfdfdOrganisms of the same order are more similar that that of the same class. Many evolutionary connections can be drawn from looking at the order; only a few features separate the organisms as a break in the evolutionary chain. One example is that within the class Mammalia, carnivores are separated into the order Carnivora while Insect-eaters are separated into the order Insectivora.
dfdfdfdfTrypanosome's Home: Kinoplastida

Family
dfdfdffEven more specific, the animals within this share a very close similarity between each other. Most will probably have the same behavior patterns, feeding habits, and general functions. An example is the Cat Family (Felidaes) which all have whiskers, sharp claws, and include animals such as Lions and Cats.
dfdfdfdfTrypanosome's Home: Trypanosomatidae

Genus
dfdfdfdThis is the part that makes up the first word of the binomial nomenclature of an organism. All the organisms within their genus may look very similar to each other. And although it is at most times not healthy, organisms of the same genus may breed with each other.
dfdfdfdfTrypanosome's Home: Trypanosoma

Species
dfdfdfdfThe most specific unit of classification is the species. The species makes up all the organisms and their apparent ancestors and descendants. Members of the species are much similar to their parents and can freely breed with other members of the same species without much complication.
dfdfdfdfTrypanosome's Home: Trypanosoma brucei and cruzi