A D V A N C E D
B I O L O G Y
C H A P T E R
1 4 :
C L A S S I F I C AT I O N
N O T E S
INTRODUCTION
• You can observe the diversity of life in among the species of organisms. One of the major goals
in biology is to identify, characterize, and classify the organisms living on Earth. Grouping will
make it easier to work with the information about features of organisms.
• Biological classification is the grouping of organisms into specific categories based on a set of
criteria.
CL ASSIFICATION
SYSTEMS
CLASSIFICATION SYSTEMS
• Taxonomy is a branch of system biology that involves the identifying, describing, naming, and
classification based on the natural relations of all other organisms.
• System biology involves study and modelling of biological components including molecules,
cells, organisms or entire species.
ARTIFICIAL SYSTEM OF CLASSIFICATION
• The artificial system of classification is the system that doesn’t make meaningful groups
• Ex. Putting all land animals in one group, all aquatic organisms in one group, or all green
creatures in one group
• These groupings are not meaningful, for example sea weed and sharks are both aquatic
organisms, but they have almost nothing in common.
NATURAL SYSTEM OF CLASSIFICATION
• The natural system of classification is the most useful system to the biologist.
• It takes into account certain relationships among all organisms, the important features shared
as large groups as possible and places organisms into distinct groups.
• The Linnaean system of classification is the most widely accepted natural system of
classification.
NAMING
SYSTEM OF
ORGANISM
NAMING SYSTEM OF ORGANISMS
• Organisms have different names in different languages, but each organism has one correct
scientific name.
• This scientific name can be understood by anyone as the same organism, and there won’t be
confusion in calling or naming organisms.
• The method of naming organism is the Binomial System of Nomenclature, or Binomial
nomenclature. It is the formal system of naming species which each organism’s name has two
parts. The first part is the genus name, and the second part is the species name.
RULES IN WRITING THE SCIENTIFIC NAMES
1.
The first letter of the genus name is always capitalized, but the rest of the genus name and
species name are lowercase.
2.
In printed form, the scientific name should be italicized.
3.
When handwritten, the scientific name should be underlined.
4.
When abbreviating the scientific name, the genus name is abbreviated to the first letter. Ex.
H. sapiens for Homo sapiens.
HIERARCHICAL
SYSTEM OF
C L A S S I F I C AT I O N
HIERARCHICAL SYSTEM OF
CLASSIFICATION
• Today’s classification system arranges organisms into groups of a descending hierarchy.
• Hierarchy consist of different levels of organization called taxa.
• In lower taxa, there is more similarities between organisms of the same taxa.
• Hierarchy:
1.
Domain
2.
Kingdom
3.
Phylum
4.
Class
5.
Order
6.
Family
7.
Genus
8.
Species
HIERARCHICAL SYSTEM OF
CLASSIFICATION
• Domain is the broadest taxa.
• Kingdom is composed of related phyla.
• Phyla is a group of similar classes.
• Class is a group of related orders.
• Order is a group of related families.
• Family is a group of apparently related genera.
• Genus is a group of similar closely related species/
• Species is a group of organisms that can interbreed and produce a fertile offspring.
• Taxa can be expanded when necessary.
HIERARCHICAL SYSTEM OF
CLASSIFICATION
• The example of the hierarchy for Grey Wolf.
CL ASSIF YING
ORGANIMS
DOMAIN & KINGDOM
• Refined methods in classification led to the three-domain, six kingdom classification system.
• The three domains are Bacteria, Archaea, and Eukarya.
• The six kingdoms are Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia.
• The previous classification system didn’t have the domain taxon, and there were only 5
kingdoms: Monera (Prokaryota), Protista (Protoctista), Fungi, Plantae and Animalia
• The organisms are classified into domains based on the cell type, and into the kingdoms based
on the cell structure and method of nutrition.
DOMAIN BACTERIA
• Bacteria are prokaryotic organisms which are members of the domain and kingdom bacteria.
• Characteristics:
1.
Prokaryotic (lack true nucleus and membrane-bound organelles)
2.
cell wall with peptidoglycan
3.
Unicellular
4.
Autotrophic or Heterotrophic
• Bacteria are very diverse and they can vary in nutrition and habitat environment
• Bacteria reproduce asexually
• Examples: E. coli, S. aureus, B. lactis
Image from http://images.celebeat.com/data/images/full/10030/bacteria.jpg
DOMAIN ARCHAEA
• Archaebacterial are prokaryotic organisms that are members of domain and kingdom Archaea.
• Characteristics:
1. Prokaryotic
2. Cell wall without peptidoglycan
3. Unicellular
4. Autotrophic or heterotrophic
• They are extremophiles, which means they live in extreme environment.
• They can be found in boiling hot springs, thermal vents, and salty water.
• Archaebacterial reproduce asexually by binary fission
• Examples: Halophiles, Thermophiles, Methanogens
Image from https://upload.wikimedia.org/wikipedia/commons/0/08/Thermal_hot_spring.jpg
DOMAIN EUKARYA
• Eukaryotes are organisms with cell that has true nucleus and membrane-bound organelles.
• They are member of domain Eukarya.
• Domain Eukarya consist of 4 kingdoms
1. Protista
2. Fungi
3. Plantae
4. Animalia
DOMAIN EUKARYA:
KINGDOM PROTISTA
• Protista are eukaryotic organisms that are either unicellular, colonial (exist in colonies) or
multicellular.
• Protists are extremely diverse from each but fits neither into plants or animals.
• 3 Categories of Protists
1. Algae – plant-like protists
2. Slime Molds or Mildews – fungus-like protists
3. Protozoan – animal-like protists
• Characteristics
1.
2.
3.
4.
Eukaryotic
Cell wall of Cellulose (some have chloroplasts)
Unicellular, Multicellular, or Colonial
Autotrophic or Heterotrophic
• Protists reproduce asexually via meiosis
• Examples: Amoeba, Euglena, Green Algae, Slime molds
Image from http://www.stgeorgeschool-hermann.com/eighth/p-protist.gif
DOMAIN EUKARYA:
KINGDOM FUNGI
• Fungi (Fungus, singular) are eukaryotic organisms that are either unicellular or multicellular.
• Fungi obtain food nutrients from organic materials from the environment by absorption.
• Characteristics
1.
Eukaryotic
2.
Cell wall of Chitin
3.
Unicellular, Multicellular, or Colonial
4.
Heterotrophic
• Fungi can reproduce sexually or asexually
• Examples: Mushrooms,Yeasts, Mold
Image from http://cf.lnwfile.com/_/cf/_raw/ne/xb/su.png
DOMAIN EUKARYA:
KINGDOM PLANTAE
• Plants are eukaryotic organism that are multicellular autotrophs.
• Plants make their own food through the process of photosynthesis.
• Characteristics
1.
Eukaryotic
2.
Cell wall of Cellulose
3.
Have Chloroplast
4.
Multicellular
5.
Autotrophic
• Plants reproduce sexually or by mitosis
• Examples: Trees, grasses, gymnosperms, lily
Image from http://www.officialpsds.com/images/thumbs/plant-psd79290.png
DOMAIN EUKARYA:
KINGDOM ANIMALIA
• Animals are eukaryotic organism that are multicellular, whose cells lack cell walls and
chloroplasts.
• Most animals are motile, which means they can move by themselves.
• Characteristics
1.
Eukaryotic
2.
No cell wall
3.
No chloroplast
4.
Multicellular
5.
Heterotrophic
• Animals can reproduce sexually or asexually
• Examples: Cat, Duck, Fishes, Sponge
Image from http://www.vetray.com/wp-content/uploads/2012/11/animals.png
DETERMINING SPECIES
• It is complicated and intricate to classify organisms at the species taxa than in any other level
in the hierarchy, because there are lots of similarities that the organisms in the same genus
have in common. It is not always easy to define or describe a species, so there are several ways
of classifying a species.
• 4 concepts:
1. Biological Species Concept
2. Morphological/ Topological Species Concept
3. Ecological Species Concept
4. Phylogenetic Species Concept
BIOLOGICAL SPECIES CONCEPT
• This concept determines and classifies species as a group of organisms that are able to
interbreed and produce fertile offspring in a natural environment.
• This concept is most commonly used in classification.
• Limitations:
1.
Some different organisms that are not in the same species can interbreed and produce a fertile
offspring, Dogs and wolves are good example, they are in the same genus but different species, and
they still can interbreed and produce a fertile offspring.
2.
The species that are already extinct couldn’t be classified by this concept.
MORPHOLOGICAL/TOPOLOGICAL SPECIES
CONCEPT
• This concept determines and classifies species based on comparisons of physical characteristics
or traits with the type sample or specimen.
• Limitation: The limitation of this concept is that in a species, there can be more than one trait
for a character, organisms can have different appearance in some characteristics, but they could
be from the same species. So this concept can be too subjective.
ECOLOGICAL SPECIES CONCPET
• This concept determines and classifies species based on its role in ecosystem and its
adaptation to specific functions in a community.
• Limitation: The limitation is that two organisms may come from the same species, but they
could be different in the way they feed, live, and function in a community.
PHYLOGENETIC SPECIES CONCEPT
• This concept determines and classifies species based on phylogeny.
• Phylogeny is the evolutionary history of organism.
• It defines species as a group of organisms that came from one single ancestral parent.
• It works well because it can account for the extinct species.
• Limitations: The limitation is that the history of some species may not be known or not enough
to classify.
M ET H O D S A N D
F E AT U R E S U S E D I N
C L A S S I F I C AT I O N
OF ORGANISMS
KEY FOR IDENTIFICATION
• Organisms can be classified be designing and following an key Identification.
• Dichotomous key is a key identification that consists of series of “yes” or “no” questions that
will lead to the correct classification for an organism.
• It works by comparing the feature and characteristics of the unknown with the known
organisms and follow yes” or “no” questions.
• Example of Dichotomous key:
http://study.com/cimages/multimages/16/key_simple_example.png
CHARACTERISTICS USED IN
CLASSIFICATION
• Many characteristics are used in the classification of organisms.
1.
Morphological Features – comparing the appearance of the organisms
2.
Biochemical and Physiological features – comparing of chemistry and biological molecules,
and how the organisms function chemically in their bodies.
3.
Genomic features – comparing the DNA, RNA , and protein, also comparing the
chromosome number, structure, and genomic sequence of the organism.
REFERENCES
• advBIOLOGY_-_CHAPTER_14_CLASSIFICATION.pdf
• http://examples.yourdictionary.com/kingdom-examples.html