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Classification
Chapter 18
• Taxonomy: Life's Filing System - Crash Course
Biology #19 - YouTube
Strawberry, peach, apple, banana,
watermelon
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How can you classify fruits?
• Construct a table with five rows and four columns. Label each row
with the name of a different fruit.
• Observe each fruit and choose four characteristics by which you can
tell the fruits apart. Label the columns in your table with these four
characteristics.
• Record a description of each fruit in your table.
• Think About It
• Observing What characteristics did you use to describe the fruits?
• Classifying Based on your table, which fruits are most closely
related? Explain.
• Finding order in diversity
– scientists named 2.5 million species
– estimated 4-30 million additional species yet to be
discovered
• Why classify
– To avoid confusion caused by common names, biologists assign
each species a scientific name
– To study the diversity of life, biologist use a classification system
to name organisms and group them in a logical manner
– Taxonomy – discipline of assigning each organism a universally
accepted name
• * have students stand up
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1) over 5 feet tall stay standing
2) brown eyes stay standing
3) female stay standing
4) left handed stay standing
• Assigning scientific names
– Binonomial nomenclature
» Each species is assigned a twopart scientific name
» Written in italics, first word is
capitalized, second is lower
case
• Ex. Grizzly bear Ursus
arctos
• Ursus – genus
• arctos – species
• there are 5 other
types of bears in
the same genus
Ursus
• Linnaeus’s systen of classification
– Taxon – group into which organisms are classified
– Linnaeus’s system of classification uses seven
taxonomic categories. They are –from smallest to
largest – species, genus, family, order, class, phylum
and kingdom
» Family – group of genera and share many
characteristics
» Order- group of similar families
» Class – group of closely related orders
» Phylum – group of closely related classes
» Kingdom – group of closel related phyla
• Two videos on website
• prentice hall Biology book
Key Concept How are living things organized for study?
Using a classification system to name organisms with a universally accepted name. Grouped
in logical manner, more similar to one another than they are to organisms in other groups
Key Concept Describe the system for naming species that Linnaeus developed.
Each species is assigned a two part scientific name
Key Concept What are the seven taxonomic categories of Linnaeus’s classification system?
Species, genus, family, order, class, phylum, and kingdom
King Philip came over for green spaghetti
Why do scientists avoid using common names when discussing organisms?
Common names vary among languages and even among regions within a single country
Critical Thinking Applying Concepts Which category has more biological meaning—all brown
birds or all hawk like birds? Why?
All hawk like birds, because that category is based on a combination of significant structures,
not just color
Cell Type
• Prokaryote
– Organisms that
DO NOT HAVE a
membrane bound
NUCLEUS
• Eukaryote
– Organisms that
HAVE a membrane
bound NUCLEUS
Body Type
• Unicellular
– Uni- means ONE
– Organism made
up of ONE CELL
• Multicellular
– Multi- means MANY
– Organism made up of
MANY CELLS
Nutrition
• Autotrophic
– Create their own
energy from sun or
chemicals
– Producers
• Heterotrophic
– Rely on other
organisms for energy
– Consumers
Cell Wall
• Cell structure that
surrounds a cell
• Provides support and
protection
• Can be made up of:
chitin, cellulose,
peptidoglycan, silica,
proteins
MODERN EVOLUTIONARY CLASSIFICATION
• Problems with traditional classification
– vultures american, african and asian
» american habit of urinating on legs to cool themselves, same as storks.
African and asian vultures do not.
• Evolutionary classification
• Overhead of humans and apes
– guided by evolutionary theory, biologists new group organisms into categories
that represent lines of evolutionary descent, not just physical similarities
– evolutionary classification – method of grouping organisms according to how
recently descended they are from a common ancestor.
– traditional classification – figure 18-7
– Classification using cladograms
» Cladistic analysis identifies and considers only characteristics that are
evolutionary innovations, new characteristics that arise as lineages evolve
over time
» Derived characters – unique features that appear in some organisms but not
others
» Cladograms – branching diagram used to show the diverging sequence in
which key evolutionary changes occurred
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Limpet
Barnacle
crab
Cladograms
• A cladogram is a diagram used to show
ancestral relationships between organisms
• Evolutionary tree of life
QUICK LAB PG. 453 How is a cladogram constructed?
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Procedure
Identify the organism in the table that is least closely related to the others.
Use the information in the table to construct a cladogram of these animals.
Analyze and Conclude
Analyzing Data What trait separates the least closely related organism from the
other animals?
• Classifying List the animals in your cladogram in order of distance from the least
closely related organism.
• Drawing Conclusions Does your cladogram indicate that lizards and humans share
a more recent common ancestor than either does with an earthworm? Explain.
• Inferring Where would you
insert a frog
if you added it to the
cladogram?
Explain your answer.
Cladogram
Frog
Lizard
Earthworm
Trout
Amniotic
Egg
Human
Hair
Legs
Backbone
18
Tools for Classifying
• Dichotomous Keys
Similarities in RNA and DNA
– all living organisms use RNA and DNA the same way
– Common ancestry evident in genes
» The genes of many dissimilar organisms show
important similarities at the molecular level. These
similarities can be used as criteria for classification
» Common gene structure indicator of common
ancestory
• Similar common feature of all living cells – the
ribosome – the cellular “protein factor”.
• Gene that codes for myosin found in muscles in
humans intercellular parts to move in yeast
Molecular clocks
– molecular clock – model used
to estimate the length of time
that 2 species have been
evolving independently based
on mutations in an organisms
DNA
Section assessment 1-5 pg. 455
Key Concept How is information about evolutionary relationships useful in
classification?
Organisms are placed in various taxonomic groups based on evolutionary descent.
Key Concept How are genes used to help scientists classify organisms?
Scientists compare DNA of different organisms to establish similarities between
them and reconstruct possible evolutionary relationships
What is the principle behind cladistic analysis?
traces the process of evolution in a group of organisms by focusing on unique
features that appear in some organisms but not in others
Describe the relationship between evolutionary time and the similarity of genes in
two species.
The longer it ahs been since two species descended from a common ancestor, the
more different their genes are likely to be.
Critical Thinking Applying Concepts How have new discoveries in molecular biology
affected the way in which we classify organisms compared with the system used by
Linnaeus?
New ways of classifying organisms reflect evolutionary relationships based on
genetic similarities, whereas Linnaeus’s system of classifying organisms was based on
physical similarities between organisms
Constructing a Chart
Draw a cladogram of a manufactured item
Automobiles
Candy
Video games
Computers
????
Kingdoms and Domains
• The tree of life evolves
– in the beginning…… then……. The six kingdom system of
classification includes the kingdoms ANIMALIA,
PLANTAE, FUNGI, PROTISTA, AND 2 BACTERIAL
KINGDOMS EUBACTERIA AND ARCHAEBACTERIA.
• The 3 domain system
– Domain – is a more inclusive category than any other –
larger than a kingdom.
– The three domains are: the domain of bacteria, which
corresponds to the kingdom Eubacteria; the domain
archae, which corresponds to the kingdom
archaebacteria; and the domain eukarya, which is
composed of animals, plants, fungi, and protists.
– Bacteria
» Domain of unicellular prokaryotes that have cell walls containing
peptidoglycans
– Archaea
» Domain of unicellular prokaryotes that have cell walls that do not
contain peptidoglycans
– Eukarya
» Domain of all organisms whose cells have nuclei, including protists,
plants, fungi and animals
• Protistsa – kingdom composed mainly of single – celled
eukaryotes: includes all eukaryotes that are not classified as
plants, animals or fungi
• Plantae – kingdom of multicellular photosynthetic autotrophs
that have cell walls containing cellulose
• Fungi – kingdom composed mainly of saprophytes, which
obtain energy and nutrients from dead and organic matter
• Animalia – kingdom of multicellular eukaryotic heterotrophs
whose cells do not have cell walls
CLASSIFICATION OF LIVING THINGS
DOMAIN
KINGDOM
CELL TYPE
NUMBER OF CELLS
MODE OF NUTRITION
EXAMPLES
Domains and Kingdoms
Archaebacteria
Archaebacteria
Protista
Bacteria
Eubacteria
Fungi
Eukarya
Animalia
Plantae
Kingdom Archaebacteria
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Cell Type: prokaryote
Cell Wall: not composed of peptidoglycan
Body Type: unicellular
Nutrition: autotrophic vs. heterotrophic
Examples: Ancient bacteria--Extremophiles
methanococcus; halophiles
Kingdom Bacteria
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Cell Type: prokaryote
Cell Wall: composed of peptidoglycan
Body Type: unicellular
Nutrition: autotrophic & heterotrophic
Examples: Common bacteria
E. coli, streptococcus, staphylococcus
Kingdom Protista
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Cell Type: Eukaryotic
Cell Wall: silica, calcium carbonate, proteins
Body Type: unicellular & multicellular
Nutrition: autotrophic & heterotrophic
Examples: Misfits like--paramecium, euglena,
amoeba
Kingdom Fungi
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Cell Type: eukaryotic
Cell Wall: chitin
Body Type: unicellular & multicellular
Nutrition: heterotrophic (not a plant!)
Examples: yeast, morel, puffball,
Rhizopus stolonifer (bread mold)
Kingdom Fungi
Kingdom Plantae
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Cell Type: eukaryotic
Cell Wall: composed of cellulose
Body Type: multicellular
Nutrition: autotrophic
Examples: corn; ferns; roses; pine tree
Kingdom Animalia
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Cell Type: eukaryotic
Cell Wall: no cell wall
Body Type: multicellular
Nutrition: heterotrophic
Examples: manatee, shark, snakes, worms, coral,
hummingbird, insects….