18-3 Kingdoms and
Domains
The Tree of Life Evolves
 Organisms
originally grouped as
either plant or animal
 Scientists
realized that bacteria,
protists and fungi were quite
different from plant and animal
groupings
Tree of Life Evolves
 Bacteria
and protists were placed in
the kingdom Protista
 Fungus,
yeasts and molds placed in
kingdom Fungi
Tree of Life Evolves
 Realized
bacteria lacked nuclei and
organelles
 Regrouped
into kingdom Monera
Tree of Life Evolves
 This
process lead to 5 kingdoms:
– Monera
– Protista
– Fungi
– Plantae
– Animalia
Tree of Life Evolves
 In
recent years, it has been
discovered that bacteria fit into 2
distinct categories
 Monera
has been broken into:
– Archaebacteria (ancient bacteria)
– Eubacteria (new bacteria
The Three Domain System
 Domain
is a more inclusive category
than kingdom
 Three
domains:
– Eukarya: includes protists, fungi, plants,
and animals
– Bacteria: includes kingdom Eubacteria
– Archaea: includes kingdom
Archaebacteria
Domain Bacteria
 Members
of domain bacteria are
unicellular and prokaryotic
 Have
thick, rigid cell walls around
cell membrane
 Cell
wall contains peptidoglycan
Domain Bacteria
 Ecologically
diverse – free-living soil
organisms to deadly parasites
 Some
photosynthesize others don’t
 Some
need oxygen, others killed by
it
Domain Archaea

Unicellular and prokaryotic

Live in most extreme environments
– Hot springs, brine pools, and black organic
mud

Many only live in anaerobic environments

Cell walls lack peptidoglycan
Domain Eukarya
 Consists
nucleus
of all organisms that have a
 Composed
– Protista
– Fungi
– Plantae
– Animalia
of kingdoms:
Protista
 Eukaryotic
organisms that can’t be
classified as plant, animal, or fungi
 Members
 Most
algae
have great variety
are single-celled, multicellular
Protista
 Photosynthetic
 Some
or heterotrophic
have characteristics of fungi
– Others characteristics of plants
– Others characteristics of animals
 Examples:
amoeba, paramecium
Fungi

Heterotrophs

Feed on dead or decaying organic matter


Secrete digestive enzymes into food, and
absorb molecules through bodies
Multicellular (mushrooms) and unicellular
(yeasts)
Plantae

Multicellular

Photosynthetic autotrophs

Nonmotile (don’t move)

Cell walls that contain cellulose

Contains cone-bearing and flowering
plants, mosses and ferns
Animalia

Multicellular and heterotrophic

Do not have cell walls


Most can move about for at least part of
their life cycle
Great diversity, live in nearly every part of
planet