- Taxonomy is the branch of biology that groups and names organisms based on similarities. Taxonomists classify organisms into a hierarchy of taxa ranging from broad to specific. - Dinosaurs are more closely related to birds than reptiles based on evidence from bone structures. - Bacteria are single-celled prokaryotes that play important roles in nutrient recycling, nitrogen fixation, and producing foods and medicines. They reproduce through binary fission or conjugation.

1. Classification
Biologists want to better understand organisms
so they organize them.
One tool that they use to do this is
classification- the grouping of objects or
information based on similarities.
Taxonomy is the branch of biology that groups
and names organisms based on studies of their
different characteristics.
Biologists who study taxonomy are called
taxonomists.

2. Taxonomy
Taxonomists group similar organisms, both living and
extinct. Classification provides a framework in which to
study the relationships among living and extinct species.
Are dinosaurs more closely related to birds or to reptiles?
The bones of some dinosaurs have large internal spaces
like those in birds. In addition, dinosaur skeletons share
many other remarkable similarities with birds. Because of
such evidence, dinosaurs are more closely related to
ostriches (birds) then to lizards, which are reptiles.

3. Taxonomic rankings
Organisms are ranked in taxa that range from
having very broad characteristics to very specific
ones.
The broader a taxon, the more general its
characteristics, and the more species it contains.
The smallest taxon is species. Organisms that
look alike and successfully interbreed belong to
the same species.

4. Taxonomic rankings
Appearance of a lynx (Lynx canadenis), bobcat (Lynx
rufus), mountain lion (Felis concolor).
The lynx and the bobcat belong to the same genius
Lynx. All the species in the genus Lynx share
characteristic of having a jaw that contains 28
teeth.
Mountain lions and other lions, which are similar to
bobcats and lynxes, are not classified in the Lynx
genus because their jaws contain 30 teeth.

5. Taxonomic rankings
Bobcats, lynxes, lions, and mountain lion belong
to the same family called Felidae.
Domesticated cats, bobcats, lynxes, and lions
belong to the family Felidae. All members of the
cat family share certain characteristics.
They have short faces, small ears, forelimbs with
five toes, and hindlimbs with four toes. Most
can retract their claws.

6. Taxonomic Rankings from largest to
smallest
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Carivora
Family Felidae
Genus Lynx
Species rufus (bobcat) canadenis (lynx)

7. The Six kingdoms
1. Eubacteria – prokaryote-unicellular
2. Archaebacteria- prokaryote-unicellular
3. Protists- eukaryote - decomposers, producers,
consumers
4. Fungi- eukaryote - decomposers
5. Plants- eukaryote - producers
6. Animals- eukaryote- consumers

8. Archaebacteria: The Extremists
Archaebacteria live mainly in extreme habitats
where there is usually no free oxygen available.
Three types of archaebacteria:
1. Live in oxygen-free environments and
produce methane gas.
• Found in marshes, lake sediments, digestive
tracts of some animals, sewage disposal plants
where they breakdown sewage

9. Archaebacteria
2. Lives only in water with high concentrations
of salt.
• Utah’s Great Salt Lake and the Middle East’s
Dead Sea.
3. Lives in the hot, acidic waters of sulfur
springs.
• Cracks deep in the ocean floor, where it tis the
autotrophic producer for a unique animal
community’s food chain

10. Eubacteria
Eubacteria: the heterotrophs
Live almost everywhere and use organic
molecules as their food source.
Some are parasites, obtaining their nutrients
from living organisms.
Others are saprophytes- organisms that feed on
dead organisms or organic waste.

11. Eubacteria
Eubacteria: photosynthetic autotrophs
Live in places with sunlight because they need
light to make the organic molecules that are
their food.
Cyanobacteria are photosynthetic autotrophs
that contain the pigment chlorophyll that traps
the sun’s energy.
Cyanobacteria commonly live in ponds, streams,
and moist area lands.

12. Eubacteria
Eubacteria: chemosynthetic autotrophs
They do not obtain energy from sunlight, instead
they break down and release the energy of
inorganic compounds containing sulfur and
nitrogen in the process called chemosynthesis.
The fix nitrogen from the atmosphere into a
form plants can use.

13. The structure of bacteria
Prokaryotic cells have ribosomes that are smaller
than ribosomes of eukaryotes.
A single DNA molecule arranged as a circular
chromosome and not enclosed in a nucleus.
They have a cell membrane
Cell wall supports and protects the bacteria.
Some bacteria have flagellum
Some have a capsule around the cell wall (bacteria
with capsule are more likely to cause disease than
those without)

15. Reproduction of bacteria
1. Asexually by a process known of binary fission. A
copy of the chromosome is made. The bacteria
gets larger and the chromosome move opposite
ends of the cell. Then the cytoplasm split.
2. Sexual reproduction called conjugation. One
bacteria transfers all or part of its chromosome
to another bacteria cell through or on a
bridgelike structure called pilus that connects
the two cells. Then the bacteria goes through
binary fission.

16. Conjugation
Binary fission

17. The importance of bacteria
Nitrogen fixation- nitrogen fixing bacteria
convert nitrogen in the atmosphere into a form
plants can use.
Recycling of nutrients- decomposing bacteria
breakdown the organic materials in dead
organisms and wasted, returning nutrients, both
organic materials and inorganic materials, to the
environment

18. Importance of bacteria
Food and medicines- swiss cheese, tangy yogurt,
vinegar, cheeses. Bacteria also inhabit your
intestines and produce vitamins and enzymes
that help digest food. Some bacteria produce
important antibiotics that destroy other types of
bacteria.