CLASSIFICATION NOTES
Taxonomy—the study of grouping organisms on the basis of their similarities.
Aristotle (Greek philosopher, 350 B. C.) developed one of the first taxonomic
systems. This system was not very accurate, but was used for many years.
Carolus Linnaeus (Swedish botanist, 1700’s) known as the father of modern
taxonomy. In his system, organisms are given a scientific name consisting of two
words. The term used to describe the two words used in the scientific name are
Genus (general) and species (specific). The practice of using a two word scientific
name is called binomial nomenclature, which literally means two-word naming.
Latin is the language of scientific names.
The divisions used during modern times for classification are:
Kingdom
Phylum (Division)
Class
Order
Family
Genus
species
DOG
MAN
WHITE OAK
Animalia
Animalia
Plantae
Chordata
Chordata
Tracheophyta
Mammalia Mammalia
Angiospermae
Carnivora Primata
Fagales
Canidae
Hominidae
Fagacae
Canis
Homo
Quercus
familiaris
sapiens
alba
Dichotomous key—biological key used to determine the classification of organisms
Basis of modern classification:
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1.
Comparative morphology—comparing structural similarities of
organisms.
2.
Chromosome structure—study similarities in karyotypes.
3.
Reproductive potential—if two organisms can mate and produce fertile
offspring, they are in the same species.
4.
Biochemical similarities—study amino acids of proteins to determine
how similar two organisms are to one another. May also use
sequence of nucleotide bases in DNA or RNA.
5.
Embryology—study how reproductive cycles are similar or different,
and how homologous structures form.
6.
Physiological studies—are especially useful in classifying bacteria.
7.
Evolutionary classification—scientists now group organisms into
categories that represent lines of evolutionary descent, not just
physical similarities. The evolutionary history of a species is called its
phylogeny. A biological system of classification based on phylogeny is called
cladistics.
Varieties—same as subspecies, they can breed and produce fertile offspring but
are different in some way. May also be called breeds.
SIX KINGDOM SYSTEM OF CLASSIFICATION:
1.
Kingdom Archaebacteria—unicellular prokaryotes that do not have
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peptidoglycan in their cell walls and live in extremely hostile
environments.
2.
Kingdom Eubacteria—unicellular prokaryotes that have
peptidoglycan in their cell walls. They obtain their nutrition
by either photosynthesis (autotrophic), chemosynthesis (autotrophic), or
absorption (heterotrophic).
3.
Kingdom Protista—eukaryotic, mostly unicellular (some multicellular
algae), photosynthesis (autotrophic) and ingestion of food particles
(heterotrophic).
4.
Kingdom Fungi—eukaryotic, mostly multicellular (exception yeast),
absorption (heterotrophic)
5.
Kingdom Plantae—eukaryotic, all multicellular,
photosynthesis (autotrophic)
6.
Kingdom Animalia—eukaryotic, all multicellular,
ingestion of food (heterotrophic)
THREE DOMAIN SYSTEM—system in which domain Bacteria corresponds to
Kingdom Eubacteria, domain Archaea corresponds to Kingdom Archaebacteria, and
domain Eukarya is composed of protists, fungi, plants, and animals.
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