1. The organization of living things
Classification
The organization of living things
DOMAIN ARCHAEA
DOMAIN EUKARYA
Kingdoms
Eubacteria
Archaebacteria
Protista
Plantae
Fungi
Animalia
DOMAIN BACTERIA

2. Taxonomy
Taxonomy is the system scientist use to name organisms & put living things into groups
Organisms are grouped by how closely related they are.

3. Hierarchical system of classification
There are 8 levels of organization
The largest level, Domain is the most inclusive
Domain, kingdom, phylum/division, class, order, family, genus, species

4. 3 Domains of life Archaea Bacteria Eukaryote Prokaryotic cells
Single celled
Oldest life forms
Live in extreme environments
Bacteria
Prokaryotic & unicellular
Largest number of living things on earth
Eukaryote
Large, complex cells

6. Classification of Ursus arctos
Grizzly bear
Black bear
Giant panda
Red fox
Abert squirrel
Coral snake
Sea star
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
ORDER Carnivora
FAMILY Ursidae
GENUS Ursus
SPECIES Ursus arctos
What criteria do you think was used to narrow down each category?

7. CLASSIFICATION BASED ON VISIBLE SIMILARITIES
Phylogeny
Read this cladogram from the bottom up. The traits shown apply to everything above it. Each branch represents a different linage. The lowest line represents a common ancestor.
Living things are groups by their line of evolutionary descent.
A picture called a cladogram is used to show how organisms are related and what characteristics separate different groups
Appendages
Conical Shells
Crustaceans
Gastropod
Crab
Barnacle
Limpet
Crab
Barnacle
Limpet
Molted exoskeleton
Segmentation
Tiny free-swimming larva
CLASSIFICATION BASED ON VISIBLE SIMILARITIES
CLADOGRAM

8. Macromolecules & classification
In the past biologist could only look at physical & behavioral characteristics to classify organisms
Now we can use: RNA, DNA (nuclear & mitochondrial) and proteins
The more genes organisms have in common the more closely related they are
Which sets of mammals are the most closely related?
Those the top two animals look alike they are not closely related.

9. Binomial nomenclature
Each organism is given a unique scientific name
The name has 2 parts: genus species
The genus is always capitalized and the species is not, both are either underlined or in italics
E.g.: Usrus arctor – the grizzly bear
why do you think this naming system was developed?

10. Summary Review What is the classification of living things called?
What is it called when biologist group things by evolutionary lines?
What is a drawing of the evolutionary tree?
Examine this chart and cladogram. You should be able to construct your own cladogram using a similar type of chart.

11. Molecular Clock
By comparing differences in amino acid sequences in the same protein found in different species scientist can figure out how long ago they diverged from a common ancestor (DNA & RNA can also be used)

12. To paraphrase
As you know radiometric dating is very helpful in determining the age of fossils. We can also use the rate of genetic mutations to construct a molecular clock that can give us information about how long ago two linages diverged. As you saw with the amino acid lab, species that are more closely related have more similarities in their DNA.