The organization of living things Classification The organization of living things DOMAIN ARCHAEA DOMAIN EUKARYA Kingdoms Eubacteria Archaebacteria Protista Plantae Fungi Animalia DOMAIN BACTERIA
Taxonomy Taxonomy is the system scientist use to name organisms & put living things into groups Organisms are grouped by how closely related they are.
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
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
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?
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
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.
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?
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.
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)
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.