Transcript Slide 1
Chapter 18 The History of Life Why Classify? • So that scientists can identify what organism they are discussing or studying. • Taxonomy: A discipline where scientists classify organisms and assign each organism a universally accepted name. Common Names vs Scientific Names • Common names: – Mountain Lion – Puma – Cougar – Panther • Scientific name: – Felis concolor Binomial Nomenclature (Carolus Linnaeus) • A two-part scientific name that is assigned to an organism. Both names are written in italics. – First part is: (Upper case) – Second part is: (lower case) Genus species • Example: Humans= Homo sapiens (“wise man”) The Three Domain System • Domain: more inclusive category than any other. Larger than kingdom. • Eukarya: • Bacteria: • Archaea: Protista, Fungi, Plantae, Animalia Eubacteria Archaebacteria Carol Linnaeus • Carol Linneaus divided organisms into plants and animals. (problem?) • This didn’t cover all of the diversity of life. – Scientists came up with other kingdoms. – Monera, Protista, Fungi, Plantae, Animalia • Then they developed the 6-kingdom system that we still use today: – Eubacteria, Archaebacteria, Protista, Fungi, Animalia, Plantae. DOMAIN→ ARCHAEA BACTERIA EUKARYA EUKARYA EUKARYA EUKARYA FUNGI PLANTAE ANIMALIA KINGDOM → ARCHAEBACTERI EUBACTERIA PROTISTA CELL TYPE PROKARYOTE PROKARYOT EUKARYOTE EUKARYOTE E EUKARYOTE EUKARYOTE UNICELLULAR UNICELLULA BOTH BOTH MULTICELL. MULTICELL. NO NO YES YES YES YES YES YES YES YES YES NO WITH WITH PEPTIDOGLY CAN BOTH BOTH WITH WITH CELLULOSE NONE HETEROTROPH AUTOTROPH HETEROTROPH YES IF THEY HAVE FLAGELLA NO YES Prokaryote or Eukaryote NUMBER OF CELLS Unicellular or Multicellular CELL NUCLEUS Present or Absent CELL WALL CELL WALL WITHOUT COMPOSITI PEPTIDOGLYCAN ON NUTRITION BOTH Autotroph Heterotroph LOCOMOTI ON YES IF THEY HAVE FLAGELLA YES NO Domain: Eukarya (all eukaryotic organisms) • KINGDOMS: • Protista: have the greatest variety – unicellular & multicellular – Some photosynthetic, others heterotrophic – 3 types: plant-like, animal- like, fungus-like • Fungi: – Heterotrophs – Unicellular & multicellular – Have cell walls of chitin • Plantae: – Multicellular – Cell wall of cellulose – Autotroph • Animalia: – Multicellular – Heterotroph Domain: Archaea • Kingdom: Archaebacteria – Prokaryotic – Unicellular – Have cell wall WITHOUT peptidoglycan – Autotroph and Heterotroph Domain: Bacteria • Kingdom: Eubacteria – Prokaryotic – Unicellular – Have cell wall WITH peptidoglycan – Autotroph and heterotroph Classify these Organisms • • • • • • • Kingdom: Phylum: Class: Order: Family: Genus: Species: Animalia Chordata Mammalia Primates Hominidae Homo sapiens • Evolutionary Classification: Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities • Cladogram: Characteristics that appear in recent parts of a lineage but not in its older members are called derived characters and can then be used to construct a cladogram. Molecular Clocks (DNA and RNA) • The genes of many organisms show important similarities at the molecular level. Similarities in DNA can be used to help determine classification and evolutionary relationships.