This document provides information on biological classification systems. It discusses why classifying living things is important, provides a brief history of classification methods, and describes the current system of classification. The current system is based on 3 domains - Bacteria, Archaea, and Eukarya - which are further divided into kingdoms based on characteristics like cell structure, nutrition, and whether organisms are unicellular or multicellular. The 6 kingdoms are Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia. Each kingdom has distinguishing features that are described.

1. Classification of Living Things

2. Why Classify?

3. DIVERSITY
• Biological diversity refers to the global variety
of species and ecosystems and the ecological
processes of which they are part, covering
three components:
– genetic,
– species,
– and ecosystem diversity.

4. Why Classify?
There are more than 2.5 million different
living things on earth.
Millions more have not yet been discovered.
Life is diverse and needs to be organized.
It is organized so that scientists all over the
world have a universal method of classifying.
Organisms are placed into groups with
biological similarities.

5. Classification
• Taxonomy = science of naming and classifying
organisms
• Aristotle — classified according to similar
structures in plants and animals

6. History of Classification:
• Aristotle - 2000 years ago
• Plant or Animal
Stem differences Land dweller
Water dweller
Air dweller

7. Problems with this early system:
• Some plants and animals couldn’t be
classified using this system.
• People also used common names.
1. Common names - don’t describe things
accurately
• Example:
Jellyfish is not a fish

8. 2. Same common name for different species
Maple Trees = Silver Maple, Sugar Maple, &
Red Maple are each different species

9. Cougar, Mountain Lion, Puma
• By the 1700’s
scientists realized that
common names were
too confusing.
• They vary among
languages and even
regions.

10. 1st attempt used physical descriptions in great detail.
• “Oak with deeply
divided veins that have
no hairs on their
undersides and no
teeth around their
edges”

11. Carolus Linnaeus
• Simplified naming and
developed a system of
binomial nomenclature
• Binomial
Nomenclature - “two
names”

12. Classification: Scientific Names
• Consists of genus (plural is genera) and species
• Genus is always started with a capital letter
• Species is always lower case
• Scientific names are italicized (or underlined)
just as book titles are
• Examples:
– Quercus rubra (red oak)
– Quercus phellos (willow oak)
– Apis mellifera (European honeybee)
– Homo sapiens (humans)

13. Handwritten scientific names:
• Follow the same rules, and…..
• are always UNDERLINED!!!!!

14. The role of taxonomy
Taxonomy:
1. works out a vivid picture of the existing diversity of
life on earth,
2. provides much of the information permitting a
reconstruction of the history of life on earth,
3. reveals numerous interesting evolutionary
phenomena,
4. supplies classifications which are of great
explanatory value in biology and paleontology.

15. Biological Classification Systems
• All biological classification systems have three
important characteristics:
1. Single, universally accepted name to each
organism,
2. Organisms are placed into groups that have real
biological meaning (shared characteristics),
3. Established rules for grouping organisms.

17. Current Classification of Organisms
• Broadest taxon is now the domain
– Developed to keep existing system in place and still account
for newer discoveries from Woese and associates
– Based on rRNA sequences
– 3 domains are bacteria, archaea, and eukarya
• Bacteria is thought to be oldest and has kingdom of
Eubacteria
• Archae has single kingdom of archeabacteria
• Eukarya has the four eukaryotic kingdoms of fungi,
protista, animalia, and plantae

18. Phylogenic Tree Based on rRNA
protista
Animalae
Fungi
Plantae
EukaryaArchaeaBacteria

19. Classifying Organisms
• Six kingdoms within the 3 domains are based on
– Cell type (prokaryotic are in the domains of archaea
and bacteria, eukaryotic are in domain of eukarya)
– Cell walls (all kingdoms except animalae have cell
walls, but materials in the walls differ)
– Body type (unicellular or multicellular)
• Two are only unicellular
• Two consist of both unicellular and multicellular
• Two consist of only multicellular, many of which have
tissues and organs
– Nutrition (autotrophs, heterotrophs)

20. Kingdom / Domain Characteristics
Domain Kingdom Characteristics
Cell
type
Cell structure Body
type
Nutrition Example
Bacteria Eubacteria P Cell wall,
peptidoglycan
U A and H Enterobacteria
Spirochetes
Archaea Archaebacteria P Cell wall, no
peptidoglycan
U A and H Methanogens
Eukarya Protista E Mixed U and
M
A and H Ameoebas,
euglenas, kelps
Eukarya Fungi E Cell wall, chitin U and
M
H Yeasts,
mushrooms
Eukarya Plantae E Cell wall,
cellulose
M A Ferns, pine trees
Eukarya Animalae E None M H Birds, earthworms
KEY: P = prokaryotic; E = eukaryotic; U = unicellular; M = multicellular;
A = autotrophic; H = heterotrophic

21. Multicellularity
• Some organisms are successful as single-celled
organisms, but others develop as members of
coordinated groups of cells
• Colonies — a group of cells that are associated
permanently, but do not communicate with one
another; i.e., Volvox (a protista)
• Aggregations — a temporary collection of cells that
come together for a time and then separate; i.e.,
plasmodial slime mold (single-celled much of life but
aggregates when starved)
• True multicellularity — composed of many cells that
are permanently associated and communicate /
coordinate their activities

22. Complex Multicellularity
• Plants and animals have complex
multicellularity where cells are differentiated
• Differentiation — process after cell division
when a cell develops a specialized form and
function
• Complex organisms develop specialized cells
organized into tissues
• Tissues are organized into organs and then
organ systems

23. Domain Bacteria 1
• Has one kingdom of Eubacteria
• Cells vary in size from 0.1 to 15 μm
• Found in practically every environment on Earth
• Similar in physical structure, no internal compartments
(organelles)
• Classification characteristics
– Strong cell wall of peptidoglycan, a weblike molecule of
carbohydrate strands cross-linked by short peptide bridges
– Gene structure has no introns and is transcribed as a single
mRNA
– Gene translation apparatus is still being defined and is
based in part on amino acid sequences of ribosome proteins
and RNA polymerase

24. Domain Bacteria 2
• Kinds
– More bacteria in your mouth than mammals on Earth
– May be
• Disease cause
• Harmless
• Useful
– Energy from inorganic compounds as H2S, NH3, CH4
– Some are photosynthetic (autotrophic / producers) while
some are heterotrophic (consumers)
– Some of the heterotrophic bacteria are capable of living
without oxygen (anaerobic)
• Important as decomposers and responsible for
recycling carbon, nitrogen and phosphorus

25. Domain Archaea
• Contains a single kingdom, Archaebacteria
• Prokaryotic that diverged from bacteria very
early, and more closely related to eukaryotic
organisms
• Characteristics of
– Cell wall and membrane does not have
peptidoglycan, but contains lipids different from
eukaryotes
– Gene structure has interrupted introns
– Ribosomal proteins similar to those of eukaryotes

26. Domain Archaea 2
• Several signature sequences of DNA are common to all
archaebacteria
• Originally identified in extreme conditions (as on
Antarctica), recently found in soils and seawater
• Three basic kinds of archaebacteria
– Methanogens — obtain energy by combining hydrogen gas
and carbon dioxide to form methane gas, live deep in
swamps, and are poisoned by traces of oxygen
– Extremophiles — thermophiles live in hot places, halophiles
live in salty places, others live in very acid places or under
extreme pressures
– Nonextreme archaebacteria — found in all the same
environments that bacteria live in

27. Domain Eukarya
• Made of 4 kingdoms
• Similarities include a highly organized cell
interior (organelles), which allows for
specialization of function within the cell
• Multicellularity occurs in Eukarya only (not in all
kingdoms)
• Sexual reproduction (not in all kingdoms)

28. Protista
• Protista is a grouping of mostly unicellular , but
some multicellular organisms that have little of
nothing in common with any other kingdom of
Eukarya other than being eukaryotic
• Many are aquatic
• Some are photosynthetic, some are fungus like
and some are animal like
• Grouped into 6 groups based on physical or
nutritional characteristics

29. Protista 2
• Use pseudopodia
– Pseudopodia means “false feet” and are extensions of the cytoplasm
– Amoebas and forams included in this phylum
– Amoebas have flexible cell surface with no cell wall
– Forams have porous shells through which long, thin projections of
cytoplasm can be extended
• Use flagella
– Flagella appear as hair-like whips used to move the organism
– Cilia are small hair-like protrusions that are found in large number on the
organism and act as to move the organism
– Ciliates and flagellates are different enough that some biologist list them
as a separate phylum
– Includes some autotrophs and some heterotrophs

30. Protista 3
• With double shells
– Diatoms are photosynthetic protists with unique
double shells made of silica, like boxes with lids
– Part of plankton and may be found in freshwater or
in marine environments
• Photosynthetic algae
– Types of algae determined by type of chlorophyll it
contains
– Many are multicellular and can reproduce sexually
– Freshwater and marine environments

31. Protista 4
• Funguslike protists
– Slime molds and water molds are often confused
with fungi because they aggregate in times of stress
to produce spore-producing bodies
– Found in freshwater, damp soil and on forest floors
• Spore-forming protists
– Sporozoans are nonmotile, unicellular parasites that
form spores
– Responsible for many significant disease including
malaria
– Have a complex life cycles

32. Fungi
• Unusual and successful group of organisms
• Most are multicellular except for the yeasts
• Cell walls contain chitin (same material that
makes up a crab shell)
• Made up of long strands of cells connected end
to end called hyphae
• May pack together to form complex
reproductive structures as mushrooms
• Reproduce by variety of asexual and sexual
methods

33. Fungi 2
• Nonmotile like plants
• Not photosynthetic (heterotrophs)
• Do not ingest food as animals do
• Secrete digestive enzymes onto whatever they
are growing on
• Many are saprophytes that live on dead
organisms, while many are parasites that live on
organisms and cause diseases
• Three phyla distinguished by their type of
reproductive structures

34. Fungi 3
• Zygomycetes form structures for sexual
reproduction called zygosporangia and includes
Rhizopus stononifer (or common bread mold)
• Basidiomycetes include fungi that make
mushrooms, which are their sexual reproductive
structures produced
• Ascomycetes form sexual spores in special
saclike structures called asci. Their
reproductive structures often resemble a
cuplike structure and are called ascocarp

35. Plantae
• Complex multicellular autotrophs with specialized cells and
tissues
– Vascular tissues is made of specialized cells playing a role in
transporting water and dissolved nutrients
• Cell walls made of cellulose, a complex carbohydrate
• Cannot move from place to place though some species of plants
have motile sperm; most are rooted to ground
• Portable reproductive structures as spores and seeds enable
dispersal of plants
• Autotrophs so primary producers
• Release oxygen gas
• Cycle phosphorus, water, nitrogen and carbon
• Covers every part of the terrestrial landscape, except for
extreme polar regions and highest mountaintops
• Food sources for humans and other animals

36. Plantae 2
• Nonvascular — lack the vascular tissues to transport
water and nutrients and lack true roots, leaves and
stems; includes mosses
• Vascular — have tissues to transport water and
dissolved nutrients and true roots, leaves and stems
– Seedless vascular — most common are ferns
• Have true roots, stems and leaves
• Surfaces coated with a waxy covering to reduce water lose
• Reproduce by spores that are resistant to drying
– Seed plants — pine trees, roses, apple trees, grasses
• Nonflowering — gymnospermae
• Flowering — angiospermae

37. Animalia
• Lack cell walls
• Complex multicellular heterotrophs, cells mostly diploid and
organized as tissues
• Zygotes develop through several stages
• Specialized tissue called muscle enables them to move about
readily and even flight in some species
• Most reproduce sexually
• 99% are invertebrates (lack a backbone), rest are vertebrates
• About 35 phyla, most of which live in marine environments,
some in freshwater, and fewer still on land
• From 0.5 mm to 100 ft in size
• Roughly grouped into 6 categories: sponges and cnidarians,
mollusks, worms, arthropods, echinoderms, vertebrates