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CLASSIFICATION- Chapter 19 . Biology Miss. Schwippert. Why classify?. To study the diversity of life, biologists classify organisms and group them in a logical manner Classification: grouping organisms together with similar feature Taxonomy- the science of classifying organisms
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CLASSIFICATION- Chapter 19 Biology Miss. Schwippert
Why classify? • To study the diversity of life, biologists classify organisms and group them in a logical manner • Classification: grouping organisms together with similar feature • Taxonomy- the science of classifying organisms • Taxa- means groups • spider monkey, sea monkey, sea horse, gray wolf, firefly, crayfish, mud puppy, horned toad, ringworm, black bear, jellyfish • These names are miss leading and may be different throughout the world
How did we get here? • Early scientists started with 2 main Kingdoms: • Plants and Animals • Based purely on external anatomy. • The classification system has expanded as we learn more: • Embryology • Morphology • DNA evidence and biochemical analysis (recent)
Binomial Nomenclature • Carolus Linnaeus was the father of the modern system. He based his system on physical and social characteristics. • -written in italics (or underlined) • 1st word is Capitalized –Genus • 2nd word is lowercase —species • Homo sapiens • Pantheraleo • Pantheratigris
6 Kingdomsc Taxonomic Hierarchy 1) Species= Groups of actual or potentially interbreeding populations which are reproductively isolated from other groups. This is the most specific category 2) Genus 3). Family 4) Order 5) Class 6) Phylum 7) Kingdom= a group of related phyla. Least specific category _____ ______ ______ _________ ________ ________ _______
Evolutionary Classification • Biologist now classify organisms into categories that represent lines of evolutionary descent, or phylogeny (not just physical similarities) • They use derived characters- or characteristics that arise over time • Can be used to construct a cladogram
Dichotomous keys • Dichotomous keys help scientists identify unknown specimens • Always start with the first statement (they are always paired) and answer the questions (yes/no) based on your specimen. • Follow the directions at the end of the row to continue your search until you identify the organism by name.
DNA and RNA • Genes of many organisms show important similarities at the molecular level • Similar DNA- show relationships with other organism • Mutations in DNA show relationships • Mutations in non-coding DNA occur at a constant rate- you can tack these mutations throughout time