1. Classification of Living Things—Taxonomy
Pima Medical Institute
Veterinary Technician Program
VTT 200 General Sciences

2. Taxonomy
Taxonomy: The science of classification of all known life forms from the most simple single-cell bacteria to the most complex animal
Linnaen System developed by Swedish botanist Carolu Linnaeus
Originally classified organisms by 7 designations:
Kingdom, Phylum, Class, Order, Family, Genus, species
In past 20 years as scientists have furthered research, a more general designation has been added at top: Domain

3. Taxonomy
Many biology students have memorized the system with this pneumonic device:
Darn King Philip Came Over From Great Spain
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

4. Taxonomy
Linnaeus made sure every organism had an independent name that would differentiate it from all other organisms
Binomial nomenclature was developed:
First word is Genus (Capitalized & italicized)
Second word is species (italicized, but not capitalized)
EX: Homo sapiens; Canis familiares,
Felis domesticus

5. Domains Two Main Domains are: Prokaryote and Eukaryotes
All living things are classified under one of these domains—there are several differences
All Prokaryotes are single-celled organisms with no true nucleus—just a simple strand of DNA
Eukaryotes can be either single-celled or multi-cellular and have a true nucleus
See 6 Kingdoms Handout RE: special classification of Domain Archaebacteria

6. Size Organelles Life Cycle
Prokaryotes
Eukaryotes
Size
1-10m
10-100m
Organelles
Non-membrane bound
Membrane bound & used to compartmentalize
Life Cycle
Binary Fission
Complete life cycle with mitosis and meiosis

7. Cell Wall Nuclear Region
Prokaryotes
Eukaryotes
Cell Wall
Eubacteria have a cell wall made of peptidoglycan (amino acids and sugars)
Plants- yes- cellulose
Fungi-yes-
Chitin
Archaebacteria wall
is mainly Lipid based
Animals- no wall, but cell membrane
Nuclear Region
Nucleoid Region with no nuclear membrane
True nucleus with membrane & envelope

8. Kingdoms There are Six Kingdoms
Kingdoms Archaebacteria and Eubacteria are classified under Domain Prokaryotes
The other four Kingdoms fall under Eukaryote:
Protista Fungi Plantae Animalia
NOTE: Organisms will increase in complexity as we move across the Taxonomy chart:
Eubacteria>Archaebacteria > Protista > Fungi > Plantae > Animalia
There is a general description of all Kingdoms and evolutionary history in your handout

9. Taxonomy & Evolution
The development of organisms is a study that has caused much controversy and debate
In the late 1700’s British scientists hypothesized that similar species descended from the same common ancestor
Certain traits were not handed down by genes, but acquired during an organism’s life because of their experiences or behavior as they tried to cope with a changing environment
In the mid-1800’s Charles Darwin and Alfred Wallace proposed the theories of Natural Selection
Darwin had studied creatures on the isolated Galapagos Islands off S. America and had seen little change in these animals because of their isolation and no natural predators

10. Taxonomy & Evolution Darwin proposed:
Theory # 1—Descent with Modification:
newer forms of life are actually modified descendents of older species, these similar organisms would arise in the same geographic area
Theory # 2—Modification by Natural Selection:
Darwin proposed that organisms best suited to their environment reproduce more successfully and will survive more readily than organisms that do not adapt as well

11. Taxonomy & Evolution Basics of Natural Selection:
Some organisms have traits that make them more suitable for coping with changing environmental conditions; these organisms will then hand down such traits to offspring who will be better suited to survive
Species change over long periods of time
Darwin called these changes Mutations
IMPORTANT NOTE: Natural Selection is NOT an active process—Organisms don’t purposely acquire these traits. The environment “selects” the organisms with the traits that will make them better to cope as environments change
EX: Dinosaurs could not cope with the changing earth and were wiped out; smaller creatures were able to survive