Taxonomy Biological Classification

Taxonomy The branch of biology that deals with the classification of living organisms Dividing things with common characteristics into groups or categories Allows us to organize, track, and identify organisms in the living world

History Aristotle, the ancient Greek philosopher, divided all living organisms into 2 categories: plants and animals Plants were stationary and used photosynthesis to make food Animals were motile and ingested their food Kingdom Plantae Kingdom Animalia

The system was simple, but problems still arose Not all organisms fit into one category or the other Coral, sponges, mushrooms are stationary but do not photosynthesize Single-celled organisms that move but also photosynthesize (euglena)

The 5 Kingdom System Viruses (nonliving)

The Big Split Later it was found that there were two distinct groups in the Kingdom Monera that were not very genetically related The Kingdom Monera was split into two: Kingdom Eubacteria & Kingdom Archaea Eubacteria Archaea

Present Day: 6 Kingdoms

Number of species per Kingdom The 6 Kingdoms Number of species per Kingdom (p. 382)

The 3 Domains Some taxonomists classify organisms using domains. Domains are based on RNA (ribonucleic acid) The 3 domains are: Domain Bacteria, Domain Archaea, and Domain Eukarya

Fundamental difference: Members of the Domain Eukarya are more closely related to the Domain Archaea than to the Domain Bacteria. Fundamental difference: Domain Eukarya = eukaryotic Domain Bacteria and Archaea = prokaryotic

Eukaryotes vs. Prokaryotes Kingdom Bacteria & Archaea Kingdom Protista, Fungi, Plantae, & Animalia Very small (~0.1-10µm) Large in comparison (~100-1000 µm) Circular DNA. No nucleus. 1 chromosome. DNA is located in a nucleus. Multiple linear chromosomes Cell division NOT by mitosis or meiosis (binary fission) Cell division by mitosis & meiosis Asexual reproduction is common Sexual reproduction is common Mostly unicellular organisms Mostly multicultural organisms No membrane-bound organelles Membrane-bound organelles Anaerobic (do not require oxygen) Most are Aerobic (require oxygen)

Eukaryotes vs. Prokaryotes

Homework Read p. 380-384 P. 384 #1-7

King Phillip Came Over For Good Spaghetti Hierarchy of Groups The 6 Kingdoms are a great start at classifying living things But they are very broad, biologists need more specific details in order to identify organisms Carl Linnaeus, the father of taxonomy, developed a system of classification that is still used today King Phillip Came Over For Good Spaghetti

Binomial Nomenclature Linnaeus developed a system for naming species Whether classified by kingdoms or domains, each species as its own unique name The name has two parts: Genus (capitalized) followed by species (not capitalized) Homo sapiens (humans) Felis domesticus (house cat) Mephitis mephitis (skunk) Italicized or underlined Latin

Dichotomous Keys Are used to identify similar organisms (often within the same family or genus) Have numbered steps; at each step there is a choice between two characteristics (usually opposites) Each step finishes with either an instruction to go to another step, or an answer which identifies the organism The number of pairs of clues is one less than the number of organisms to be identified

Homework Read p. 390-396 P. 396 #1 & 5 Shark & Ray Dichotomous Key (Handout) Fairytale Creature Dichotomous Key Poster