Chapter 18: Classification

You are required to put on clothes each day before coming to school. How do you go about this in the most efficient manner to get you out of the house on time for school each day?

• There are 1.5 million different identified species (alive and extinct)

• How can we keep all these organisms in order?

• Classification – is the method of logically grouping

organisms based on some common characteristics

• Taxonomy – does the actually grouping into the groups

called TAXON (s – TAXA) with some kind of biological significance.

– Ie. Things that fly, swim, walk, have feathers, etc.

How many different terms can you think of for trying to tell someone something is really good?

Do these terms have meanings that may confuse someone else?

• There is a need for a common term to describe an individual organism so that all people understand when the term is used.

• Carolus Linnaeus (mid 1700’s) came up with the system of Binomial Nomenclature.

Carolus Linnaeus

• He assigned two Latin names to each different species of organisms.

• This is their Scientific name. • Homo sapiens (human) Homo sapiens

Ursus maritimus (polar bear) Ursus maritimus

Acer rubrum (red maple)

Ursus arctos (grizzly bear)

Cur Latin?

• Scientific names will always be in Latin.

• Latin is a dead language that will not evolve unlike other languages.

• Little chance of change through time.

• Universally understood in the science community

The Taxonomic order:• From the largest, most inclusive group to the

smallest, most exclusive, specific taxa.

Taxa Human Grizzly ChimpKingdom Animalia Animalia AnimaliaPhylum Chordata Chordata ChordataClass Mammalia Mammalia MammaliaOrder Primate Carnivora PrimateFamily Hominoidae Ursidae HominoidaeGenus Homo Ursus PanSpecies sapiens arctos troglodyte

Which two organisms are more closely related and why?

• Modern methods of classification rely on evolutionary relationships in place of homologous structures.

• Birds, bats and insects should not be classified together because they all have wings and fly.

• Evolutionary classification classifies organisms in taxa based on lines of common descent, not physical similarities– Uses proteins, DNA and genes to determine

classification and relatedness

• Human Genome project that decoded our DNA helped to show evolutionary relationships with other species, even totally unrelated species. Think back to your Amino Acid lab– The more closely related organisms are, the more

Amino acids they will have in common and the more recently they evolved from some kind of common ancestry.

Kingdoms and Domains

• 1700’s – Plants and Animals only

• 1800’s – Protists, Plants and Animals

• 1950’s – 5 Kingdom system, including Fungus and Monera

• Now – 6 Kingdoms divided into 3 Domains

Domains:Domains:1.1. BacteriaBacteria – Unicellular, prokaryotic (no

nuclear membrane) with cell walls made up of peptidoglycan.

– Kingdoms: EubacteriaKingdoms: Eubacteria – true bacteria. “Normal “ bacteria

2.2. ArchaeaArchaea – Unicellular, prokaryotic but do not have cell walls containing peptidoglycan. These are primitive organisms that could withstand very harsh environments and a lack of oxygen.

– Kingdom: ArchaebacteriaKingdom: Archaebacteria – methanogens in the digestive tract of animals and halophiles that live in the Dead Sea.

3. EukaryaEukarya – Eukaryotic organisms. May be uni or multi cellular. All have nuclear membranes

– Kingdom: ProtistaKingdom: Protista – basically unicellular. Have plant-like, animal – like or fungus- like representatives.

• ***Most difficult kingdom to classify. No clear cut boundaries.

Ie.Amoeba, paramecium, slime mold, Volvox– Kingdom FungiKingdom Fungi – Absorptive heterotrophs,

basically multicellular organisms with cell walls made up of chitin. Ie. Yeast, mushroom, molds

– Kingdom PlantaeKingdom Plantae – Multicellular, photosynthetic organisms. All are autotrophic. Nonmotile with cell walls containing cellulose. Ie. Mosses, ferns, conifers, flowering plants and some algae.

– Kingdom AnimaliaKingdom Animalia – Multicellular, ingestive heterotrophs. All lack cell walls. Motile for some time in their life cycle. Ie. Sponges, jelly fish, worms, insects, octopus, fish, birds, reptiles, you

The New and Improved Six Kingdom System Kingdom Cell Type # of Cells Nutrition

Representative organism

Archaebacteria Prokaryotic UnicellularAutotrophic or Heterotrophic

Blue-green bacteria, Methanogens

Eubacteria Prokaryotic UnicellularAutotrophic or Heterotrophic

E.coli, Staphylococcus, Streptococcus,

Spirochetes

Protista EukaryoticUni, multi or

colonialAutotrophic orHeterotrophic

Amoeba, Paramecium, Euglena,

Plasmodium, Diatoms

Fungi EukaryoticUni or

MulticellularAbsorptiveHeterotroph

Yeast, Mushrooms, Molds, smuts,

rusts

Plantae Eukaryotic MulticellularAutotrophic

(some heterotrophic)

Mosses, ferns, Horsetails, Conifers,

Flowering plants

Animalia Eukaryotic MulticellularIngestive

Heterotroph

Sponges, Coral, Sea stars, EW,

Insects, Fish, Amphibians,

Reptiles, Birds, Mammals