Classification

Chapter 18

18.1 Finding Order In Diversity

Why do you think we would need to classify?

To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner.

Why Classify?

Taxonomy:A discipline where scientists classify

organisms and assign each organism a universally accepted name

Why Classify?

Depending on where you are this animal could be called a mountain lion, puma, cougar or a panther– all of which are common names

However the scientific name is Felis concolor

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Assigning Scientific Names

Using scientific names made it easier to give one name to one animal because common names have very different meanings in different areas or they are just different all around.

Binomial Nomenclature

Carolus Linnaeus A Swedish botanist During the early 18th Century (1707-1778), he

created a 2 word naming system

Binomial Nomenclature

Each species is assigned a 2-part scientific nameAlways written in italicFirst word is capitalizedSecond word is lower cased

Ex: Grizzly Bear is called Ursus arcotos

Binomial Nomenclature

First part of the name is the genus the animal belongs to

Genus:Group of closely related species

Second part of name is unique to each species within a genus

Linnaeus’ System of Classification

Linnaeus’ hierarchical system of classification includes 7 levels

From largest to smallest:Kingdom, Phylum, Class, Order, Family,

Genus, Species

Linnaeus’ System of Classification

Taxon:Each level or group of organization into which

organisms are classified.

Kingdom:Largest taxonomic group. Most inclusive of

closely related phyla

Linnaeus’ System of Classification

Phylum:Several different classes make up a phylum:

they are closely related

Class:Composed of similar orders, larger categories

Linnaeus’ System of Classification

Order:Broad taxonomic categories composed of

similar families

Family:Group of genera that share the same

characteristics

18.2 Evolutionary Classification

Phylogeny: Evolutionary relationship among organisms

Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny not just physical similarities.

Evolutionary Classification

Evolutionary ClassificationStrategy of grouping organism together based

on their evolutionary history

The higher the level of taxon, the farther back in time is the common ancestor of all the organisms in the taxon

Classification Using Cladograms Derived characters

Characteristics that appear in recent parts of a lineage but not in its order members

CladogramDiagram that shows the evolutionary

relationships among a group of organisms

Characteristics/ Traits

Organisms Crab

Barnacle

Molted External Skeleton

Segmentation

Limpet

Tiny free flowing Larvae

Items to the left: organisms has it

Items to the right: organism does not have it

Similarities in DNA and RNA

The gene of many organisms show important similarities at the molecular level.

Similarities in DNA can be used to help determine classification and evolutionary relationships.

18.3 Kingdom and Domains

5 KingdomsMonera, Protista, Fungi, Plantae and Animalia

6 KingdomsBiologists came to recognize that the Monera

were composed of 2 distinct groups

Kingdoms and Domains

As a result, Monera have been separated into 2 kingdoms: Eubacteria and Archeabacteria

Eubacteria, Archeabacteria, Monera, Protista, Fungi, Plantae and Animalia

The 3 Domain System

Domain: A more inclusive category than any other larger than

a kingdom

Domain Eukarya is composed of Protista, Fungi, Plantae, and Animalia

Domain Bacteria is composed of Eubacteria Domain Archaea is composed of Archaebacteria

DOMAIN

KINGDOM

CELL TYPE

CELL STRUCTURES

NUMBER OF CELLS

MODE OF NUTRITION

EXAMPLES

Bacteria

Eubacteria

Prokaryote

Cell walls with peptidoglycan

Unicellular

Autotroph or heterotroph

Streptococcus, Escherichia coli

Archaea

Archaebacteria

Prokaryote

Cell walls without peptidoglycan

Unicellular

Autotroph or heterotroph

Methanogens, halophiles

Protista

Eukaryote

Cell walls of cellulose in some; some have chloroplasts

Most unicellular; some colonial; some multicellular

Autotroph or heterotroph

Amoeba, Paramecium, slime molds, giant kelp

Fungi

Eukaryote

Cell walls of chitin

Most multicellular; some unicellular

Heterotroph

Mushrooms, yeasts

Plantae

Eukaryote

Cell walls of cellulose; chloroplasts

Multicellular

Autotroph

Mosses, ferns, flowering plants

Animalia

Eukaryote

No cell walls or chloroplasts

Multicellular

Heterotroph

Sponges, worms, insects, fishes, mammals

Eukarya

Domain Bacteria

Unicellular and prokaryotic Cell walls with peptidogylcan

Domain Archaea

Unicellular and Prokaryotic

Cell walls with out peptidogylcan

Live in some of the most extreme environments you can imagine

Domain Eukarya

Consists of all organisms that have a nucleus Protista:

Composed of eukaryotic

organisms that cannot be

classified as animals,

plants or fungi Members share great

variety

Domain Eukarya

Fungi: Heterotrophs: most

feed on dead or decaying matter

They secrete digestive enzymes on food and absorb food molecules

Domain Eukarya

Plante:Multicellular, photosynthetic autotrophsCone-bearing and flowering plants, mosses

and fernsCells have cell walls

Domain Eukarya

Animalia:Multicellular heterotrophsCell walls have no cell wallsThey move for part of their lives