classification notes. taxonomy naming and grouping organisms according to their characteristics and...
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Classification Notes
Taxonomy
• Naming and grouping organisms according to their characteristics and evolutionary history.
Aristotle
• Greek philosopher who first attempted to classify living organisms
• Over 2000 years ago
Aristotle
• He classified living things into two groups:– Plants – Animals
Aristotle
• Why did his system create problems?– Not all living things are
plants and animals– Even plants and
animals are very diverse
– Our knowledge of life has changed
Carolus Linnaeus
• Swedish scientist who developed our modern system of classification.
• 1707 - 1778
Carolus Linnaeus
• Used morphology (form and structure) to categorize organisms
Carolus Linnaeus• Developed a hierarchy of levels in his
system– Kingdom King– Phylum Phillip– Class Came– Order Over– Family For– Genus Good– Species Soup
Species
• Remember that a species is a group of organisms that can mate and reproduce fertile offspring
• Not a clear cut definition
Common Names
• Most people use common names for organisms
• This causes problems– 13 lined ground
squirrels are often called gophers
Scientific Names
• Scientific names solve the naming problem
• Latin is used for most scientific names.
Binomial Nomenclature
All organisms are given a genus and a species name.
This way all people can use the same name to identify organisms
Genus and Species• The genus name
comes first and begins with a capital letter.– Ex. Felis (it can be
abbreviated as F.
• The species names comes second and begins with a lower case letter.– Ex. domesticus *Both the genus and species
names are usually italicized and often underlined.Ex. Felis domesticus
How do we classify organisms today?
• Not so much on physical similarities (can be based too much on opinions).
• Scientific evidence is a better way to do this.
Evidence for Classification
• Chromosome Structure
• Biochemical Similarities
• Embryology
• DNA Sequencing
• Reproduction
Systems of Classification
• Linnaeus used 2 Kingdoms– Plant– Animal
Copyright Pearson Prentice Hall
The Three-Domain System
The Three-Domain SystemMolecular analyses have given rise to a new
taxonomic category that is now recognized by many scientists.
The domain is a more inclusive category than any other — larger than a kingdom.
Copyright Pearson Prentice Hall
The Three-Domain System
The three domains are:• Eukarya, which is composed of protists, fungi, plants,
and animals.• Bacteria, which corresponds to the kingdom
Eubacteria.• Archaea, which corresponds to the kingdom
Archaebacteria.
Copyright Pearson Prentice Hall
Domain Bacteria
Domain BacteriaMembers of the domain Bacteria are unicellular
prokaryotes.
Their cells have thick, rigid cell walls that surround a cell membrane.
Their cell walls contain peptidoglycan.
Copyright Pearson Prentice Hall
Domain Archaea
Domain ArchaeaMembers of the domain Archaea are unicellular
prokaryotes.
Many live in extreme environments.
Their cell walls lack peptidoglycan, and their cell membranes contain unusual lipids not found in any other organism.
Copyright Pearson Prentice Hall
Domain Eukarya
Domain EukaryaThe domain Eukarya consists of organisms that
have a nucleus.This domain is organized into four kingdoms:
– Protista– Fungi– Plantae– Animalia
Modern Kingdoms
• Animalia
• Plantae
• Fungi
• Protista
• Archaebacteria
• Eubacteria
Animalia
• Multicellular heterotrophs
Plantae
• Multicellular autotrophs
Fungi
• Most are multicellular• Yeast is unicellular• Absorb food through
cell walls
Archaebacteria
• Unicellular prokaryotes
• Related to first life forms
• Live in harsh environments
Eubacteria
• Unicellular prokaryotes
• Includes most bacteria
Classification of a human
• Kingdom = Animalia• Phylum = Chordata• Class = Mammalia• Order = Primate• Family = Hominid• Genus = Homo• Species = sapien