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Classification
Section 18.2 & 18.3
Phylogeny:
• Evolutionary relationships among
organisms
• Biologists group organisms into categories
that represent lines of evolutionary
descent, not just physical similarities.
• The strategy of grouping organisms
together based on their evolutionary
history is called evolutionary
classification
Linnaean System vs. Evolutionary
System of Classification
• KPCOFGS came way before
scientists understood that organisms
evolved.
• The Phylogenic (Evolutionary)
System names only clades
• Clades are groups of organisms that
are all descended from a common
ancestor
Cladogram
Tree of Life
Five Kingdoms of Classification
•
Linnaeus – 2 Kingdoms (Animals and
Plants
LED TO:
1. Protista
2. Fungi
3. Monera
4. Plantae
5. Animalia
Recent Years:
Six Kingdoms:
1. Eubacteria
2. Archaebacteria
3. Protista
4. Fungi
5. Plantae
6. Animalia
TODAY = 3 Domain System
Domains:
1. Eukarya (protists, fungi, plants,
animals) (uni and
multicellular/eukaryotic)
2. Bacteria (unicellular/prokaryotic)
3. Archae (unicellular/prokaryotic)
So what is the difference between 2
&3?
Assignment
1. Read pages 451-461
2. Copy Page 459 on ONE FULL page
for your notes***
3. Answer questions 1-6 on page 461
4. Answer MC 1-10 on page 464
CLASSIFICATION
REVIEW
BIOLOGY 112
1. Why do Biologists assign
each organism a universally
accepted name?
• To provide consistency and avoid
confusion
What criteria are used to
classify an organism?
Evolutionary relationships as well as
structural similarities of the organism
What features of Binomial
Nomenclature make it useful for
scientists?
• Each name is unique. Each scientific
name (genus, species) is assigned to
only 1 species, so different species
are not confused
Sequence Linnaeus’s seven
taxonomic categories from
smallest to largest:
• Species, genus, family, order, class,
phylum and Kingdom
Explain the goal of evolutionary
classification:
• Group organisms based on their
evolutionary history instead of
grouping only according to physical
similarities
How is a Cladogram used in
classification?
• It is an attempt to trace the process of
evolution in a group of organisms by
focusing on unique shared derived
features that appear in some
organisms but not others
How Do Biologists use DNA and
RNA to Classify Organisms?
• They choose segments that are
similar in all or many organisms and
compare sequences within those
molecules. The more similar between
species, the closer the evolutionary
relationships.
What is Phylogeny?
• Study of evolutionary relationships
among organisms
Describe how a Molecular Clock is used to
Estimate the Length of Tie that Two Related
Species Have Been Evolving Independently:
• Relies on a repeating process or
MUTATION, and a comparison of
DNA sequences in two species to see
how alike or dissimilar the genes are.
• The degree of dissimilarity is, in turn,
an indication of how long ago the
species shared a common ancestor
How do Domains and Kingdoms
Differ?
• A domain is more inclusive and larger
than a kingdom
What characteristics are used to
place an organism in the
domain Bacteria?
• Unicellular and Prokaryotic
• Cell walls contain peptidoglycan
Which domain consists of
prokaryotes whose cell walls lack
peptidoglycan?
• Kingdom Archaea
Describe the 4 Kingdoms that
comprise the Domain Eukarya:
• Protists, Fungi, Plantae, Animalia
What characteristic(s) differentiate
the kingdom Animalia from
Plantae?
• Unlike members of the Plantae
kingdom, members of the Animalia
kingdom are heterotrophic, do not
have cell walls, and are motile.