Transcript Domains and Kingdoms

Domains and Kingdoms
 The broadest category in the classification
used by most biologists is the domain
 The most widely used biological classification
system has six kingdoms and three domains
 The three domains are Bacteria, Archaea,
and Eukarya
 The six kingdoms are Bacteria, Archaea,
Protists, Fungi, Plantae, and Animalia
• rRNA (ribosomal RNA) indicates archaea are
more closely related to eukaryotes than
bacteria-share a more recent common
ancestor
Domains and Kingdoms
Domain Archaea
 Archaea are thought to be more ancient than
bacteria
 Archaea are diverse in shape and nutrition
requirements
 They are called extremophiles because they
can live in extreme environments
Archaea
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•
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No peptidoglycan in cell walls
Introns
Unusual lipids in cell membranes
Genes and rRNA that resembles eukaryote
genes and rRNA
Archaea
 Thermoacidophiles live in hot, acidic
environments-hot springs, thermal vents
 Halophiles live in very salty environmentsGreat Salt Lake & Dead Sea
 Methanogens cannot live in the presence of
O2-convert H gas and CO2 into methane
Archaea
Photosynthetic
bacteria
bacteria
9560x
3000x
Domain Bacteria
 Prokaryotes whose cell
walls contain peptidoglycan
 No introns
 Diverse group-can survive in
many different environments
 Lipids in cell membranes
 Genes and rRNA unlike
eukaryotes
Gram Stain
Bacteria are divided into 2 major groups
Gram-negative-more complex cell wall, less
peptidoglycan
Gram-positive-simpler cell wall, more
peptidoglycan
Identifying Prokaryotes
 3 main shapes
 Spherical = Cocci (chains-strepto, grape-like
clusters-staphylo)
 Rod-shaped = Bacilli
 Spiral-shaped = Spirochetes
Spirochetes
Bacilli
Cocci
400x
5460x
2000x
Ecology of Bacteria
 Nutrient cycling
 Bacteria can be decomposers, returning
vital nutrients to the environment.
 Nitrogen-fixing bacteria live in a symbiotic
relationship in the root nodules of plants
such as soybeans, clover, and alfalfa.
Normal Flora
 Most of the bacteria that live in or on you are
harmless and are called normal flora.
21,674x
E. coli
Foods and Medicines
 Some foods are made with the aid of bacteria.
 cheese
 yogurt
 buttermilk
 pickles
 vitamins
Disease-causing Bacteria
 A small percentage of bacteria cause disease.
 Bacteria multiply quickly at the site of infection.
 Some bacteria secrete a toxin.
Viruses
 A nonliving strand of genetic material within
a protein coat
 No organelles to take in nutrients or use energy
 Cannot make proteins
 Cannot move
 Cannot replicate on their own
 Most viruses range in size from 5 to 300
nanometers.
Viruses—An Exception
 Viruses do not possess cells, nor are they
cells, and are not considered to be living.
 Because they are nonliving, they usually
are not placed in the biological classification
system.
Viruses
Domain Eukarya
 All eukaryotes are classified in Domain
Eukarya.
 Domain Eukarya contains Kingdom Protista,
Kingdom Fungi, Kingdom Plantae, and
Kingdom Animalia.
Kingdom Protista
 Protists are eukaryotic organisms that can be
unicellular, colonial,
or multicellular.
 Protists are
classified into three
different groups—
plantlike, animallike, and funguslike.
Protists
 All protists are eukaryotes.
 Some reproduce asexually by mitosis
while others exchange genetic material
during meiosis.
Animal-like Protists
 Protozoans are
heterotrophs and
usually ingest
bacteria, algae, or
other protozoans.
Introduction to Protists
Plantlike Protists
 Plantlike protists make
their own food through
photosynthesis.
 Algae
Funguslike Protists
 Funguslike protists
absorb their nutrients
from other organisms.
Kingdom Fungi
 A fungus is a unicellular or multicellular
eukaryote that absorbs
nutrients from organic
materials in its
environment.
 Member of Kingdom
Fungi are
heterotrophic, lack motility, and have cell walls.
Major Features of Fungi
 Cell wall composed of chitin
 Hyphae form a netlike mass called a
mycelium.
 Hyphae provide
a larger surface
area for nutrient
absorption.
Major Features of Fungi
 Hyphae are divided into
cells by cross-walls
called septa.
 Septa allow nutrients,
cytoplasm, and
organelles to flow
between cells.
 Some fungi are aseptate.
Lichens
 Provide a symbiotic relationship between
a fungus and an alga or a photosynthetic
partner.
 A green algae or cyanobacterium provides
food for both organisms.
 The fungus provides a web of hyphae in which
the algae or cyanobacterium can grow.
Lichens
 The fungus provides hyphae where the algae
or cyanobacterium can grow.
Kingdom Plantae
 Members of Kingdom Plantae form the base
of all terrestrial habitats.
 All plants are
multicellular and have
cell walls composed of
cellulose.
 Most plants are
autotrophs, but some are heterotrophic.
Kingdom Animalia
 All animals are heterotrophic, multicellular
eukaryotes.
 Animal organs often are
organized into complex
organ systems.
 They live in the water,
on land, and in the air.