Mrs. Wolodkowicz
Biology 1H
Chapter 17 Classification of Organisms
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VI.
Taxonomy- branch of Biology that names & groups organisms
according to their characteristics & evolutionary history or phylogeny.
Aristotle- first to group organisms (either plant or animal & based on
habitat (land, water, or air)) & used common names (problem: Jelly
fish-not a fish at all).
Linnaeus- (1707-1778) grouped organisms based on morphology. We
still use his system today, but we additionally group based on
phylogeny.
A. Kingdom- largest group ex. Animalia.
B. Phylum/Division (plants)- subset of kingdom ex. Chordata.
C. Class- subset of phylum ex. Mammalia.
D. Order- subset of class ex. Primates.
E. Family- subset of order ex. Hominidae.
F. Genus- Homo.
G. Species- ex. sapiens
Naming of organisms- Binomial Nomenclature. All organisms are
given 2 names that make up their scientific name. The first part of the
name is the Genus (always written in capitol letters). The second part
of the name is the species (always written in lower case letters) and
both names are underlined or written in italics. Ex. humans- Homo
sapiens (species name is usually descriptive-wise). Ex. Canis lupus.
Dichotomous key- written set of choices that leads to the name of an
organism based on its morphology. Ex. Flower, # of petals, # of leaves,
etc.
Systematic taxonomy- organizes all organisms within the context of
evolution. (Fossil record, morphology, embryonic developmental
patterns, & molecular biology (DNA).
A. Phylogenetic Tree- shows the evolutionary relationships of species
in naming them.
B. Cladistics- categorizes organisms based on shared derived
characteristics to establish evolutionary relationships. Ex. Birds:
all contain feathers; most other animals do not have feathers, thus
linking all birds with a common ancestor.
The kingdoms (6)
A. Kingdom Archaebacteria- unicellular prokaryotes (no nucleus, no
membrane organelles) that may be autotrophic or heterotrophic,
aerobic or anaerobic & often live in hostile environments (most
ancient of organisms. Live for about 30 min
B. Kingdom Eubacteria- unicellular prokaryotes. Most are aerobic,
while a few are anaerobic (bacteria). Live for about 30 min. Note:
Mrs. Wolodkowicz
Biology 1H
VII.
Archaebacteria and Eubacteria used be jointly called kingdom
Monera.
C. Kingdom Protista- Eukaryotic (nucleus & membrane bound
organelles), mostly single-celled organisms but some are
multicellular (kelp). May be heterotrophic or autotrophic Ex.
Euglena’s, amoebas.
D. Kingdom Fungi- Heterotrophic unicellular & multicellular
Eukaryotic organisms. Ex. Mushrooms, yeast.
E. Kingdom Plantae- Eukaryotic, multicellular. Most are autotrophic,
a few are parasitic. Ex. ferns, moss, oak tree, rose, grass, etc.
F. Kingdom Animalia- Eukaryotic, multicellular, heterotrophic
organisms. Ex. fish, dogs, worms, humans.
3-Domain System- another way of classifying organisms based on the
sequences of ribosomal RNA. Even prokaryotes contain RNA. Carl
Woese (1928-) used ribosomal RNA to estimate how long ago pairs of
different organisms shared a common ancestor. He grouped them by
domains.
A. Domain Eukarya- contains Protista, Plantae, Fungi, & Animalia.
B. Domain Bacteria- kingdom Eubacteria.
C. Domain Archaea- kingdom Archaebacteria.