Life On Earth
Do Now:Scientists estimate that there may be as many as 100,000,000 different species of organisms on Earth. Of these, about 1 x 107 have been identified. What % of species have not been
identified?
Today’s Big Ideas• Taxonomy is the process of organizing and classifying organisms
into different groups.
• The highest level of organization is called a domain, and there are three: Domain Eukaryota, Domain Bacteria, and Domain Archaea.
• Domain Eukaryota includes the plant, animal, fungi, and protist kingdoms, because they are all made of Eukaryotic cells (with a nucleus.)
• There are two domains of prokaryotes (no nucleus): Bacteria and Archaea.
Classifying Life
• Biologists classify organisms in two major ways:– Morphology = the structures and characteristics of
organisms– Phylogeny = the evolutionary history and
relationships of organisms
“morph” = “form”
“phylo” = “type, kind, race, or tribe”
Morphological Classification Example
• Mollusks are animals that have an organ called a mantle that makes a shell.
• Organisms with one shell are called gastropods, organisms with a double shell are called bivalves.
gastropodbivalve
Phylogenetic Classification Example• These bacteria are all
unicellular prokaryotes.
• The tree shown classifies the species according to DNA similarity
• The more similar the DNA of two species is, the more recently they shared a common ancestor.
The Modern Classification Scheme
• The picture at right shows the classification scheme used to group similar organisms together.
• Notice how each group is made up of many of the smaller groups below it.
• In other words, as you go down the picture, the groups are more specific and include less organisms
Hierarchy: An arrangement of items into groups “above,” “below,” or “at the same
level as” other groups.
Hierarchy Example: Many Classes Make up One Phylum
• The phylum chordata includes all animals that have backbones
• There are many different classes of animals that have backbones, like class rodentia (rodents), class primates, etc. etc.
Taxonomy = The practice of classification• Taxonomy is
the process or study of classification.
• A biological taxonomist is a scientist who specializes in classifying organisms
The Top Level: Domain• Domain Eukaryota is where you belong. ALL
EUKARYOTIC CELLS HAVE A MEMBRANE-BOUND NUCLEUS. They often contain other internal membranes and membrane-covered organelles, like the ER, Golgi, mitochondria, chloroplasts, and others
• Domain Bacteria and Domain Achaea: ALL BACTERIA AND ARCHAEA CELLS ARE PROKARYOTIC AND DO NOT HAVE A MEMBRANE-BOUND NUCLEUS. They also don’t have membrane covered organelles, like mitochondria and chloroplasts. They differ from one another for biochemical reasons (like phospholipid chemistry)
The Tree of Life, by DNA Similarity
Taxonomy Activity
• Your group will receive 11 items classified in the family junkus.
• Your job is to divide family junkus into several genera (genuses).
• Each genus can then be divided into 1 or more “species” of organism
Things To Include in Your Report• Unique “scientific names” of each
“species.”– Should be “latin.”– Each must be unique– Scientific names include genus and
species. Example: “Pencilum reddus.”
• A tree diagram showing the relationships of the genuses and species.
• Answers to questions – complete independently!
