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3/29/17 Dichotomous Key 1. A way to identify unknown organisms Classification 2. Contains major characteristics of groups of organisms Section 1: The Importance of Classification 3. Pairs of CONTRASTING descriptions Taxonomy: the science of describing, naming, and classifying organisms 4. After each description key either directs use to another pair of descriptions or identifies an object Genus: a level of classification that contains similar species Binominal Nomenclature: a system of giving each organism a two-word scientific name that consists of the genus name followed by the species name I. The Need for Systems A. About 1.7 million species have been named and described by scientists B. Millions more are undiscovered 1 3/29/17 C. Practice of naming and classifying organisms is taxonomy D. Taxonomic systems organize knowledge of organisms E. Systems attempt to provide consistent ways to name and categorize organisms F. Taxonomic systems do not use common names 1. May be confusing because common names are different places 2. Use categories to organize organisms Cambaridae camburus n Crayfish n Crawdad n Mudbug n Yabbie G. Biologists group organisms into large categories 1. Then smaller, more specific categories a. taxon (plural, taxa.) II. Scientific Nomenclature A. Various naming systems were invented in the early days of European biology 1. Used long, descriptive Latin phrases called polynomials 2. Names for taxa were inconsistent between these systems 3. The only consistent taxon was genus a. used to group similar species 2 3/29/17 B. Carlos Linnaeus 1. Swedish Biologist in the 1750s 2. Carl von Linne 3. Developed simpler and more consistent system C. Naming Rules 4. Two-word naming system called binomial nomenclature 5. Genus name and a single descriptive word for each species 6. Universally adopted 7. Called a scientific name 3. All the members of a genus share the genus name as the first term Lion - Panthera leo Tiger - Panthera tigris 1. No two species can have the same scientific name 4. The second term is called the species identifier, and is often descriptive 2. All scientific names are made up of two Latin or Latin-like terms 5. When you write the scientific name, the genus name should be capitalized and the species identifier should be lowercase 6. Both terms should be italicized (or underlined) 7. Example A. Apis mellifera is the European honeybee 1) The term mellifera derives from the latin word for honey III. The Linnaean System A. Devised a system to classify all plants and animals that were known B. Organisms grouped at successive levels of the hierarchy based on similarities in form and structure 3 3/29/17 C. Eight basic levels of modern classification 1. Domain 2. Kingdom 3. Phylum (Division--Plants) 4. Class 5. Order 6. Family 7. Genus 8. species (strains - Bacteria) D. Classification of Man 1. Domain 2. Kingdom 3. Phylum 4. Class 5. Order 6. Family 7. Genus 8. species Eukarya Animalia Chordata Mamalia Primates Hominidae Homo Homo sapiens Dumb Kings Play Chess On Finely Ground Sand D. Each taxon is identified based on shared traits E. Similar species are grouped into a genus F. Domain 1. Recent addition 2. Recognizes most basic differences among cell types 1. Similar genera are grouped into a family 2. And so on up to the level of domain G. Kingdom 1. Six kingdoms fit within the three domains 3. All living things grouped into one of three domains H. Phylum 1. Subgroup within kingdom I. Class 1. Subgroup within a phylum 4 3/29/17 J. Order 1. Subgroup within a class L. Genus (plural, genera) 1. Subgroup within family K. Family Subgroup within an order M. species 1. Subgroup within Genus 2. Uniquely shared traits 3. Species are thought to be closely related 4. Defined as a unique group of organisms united by heredity or the ability to interbreed 5. Scientists tend to define species based on unique features 6. Example 1. Homo sapiens a. only living primate species that walks upright b. uses spoken language Section 2: Modern Systematics Phylogenetic Tree: shows the evolutionary relationships among organisms I. Evolutionary Relationships A. Phylogenetic Tree: family tree used by taxonomists 1. Shows evolutionary relationships among species not individuals 5 3/29/17 2. Fossil Record Used 3. Comparative to family members 4. Spirochetes are most closely related to what organisms? Proteobacteria 5. Name two organisms that are distantly related II. Physical Structures 6. Classification of organisms is based on GENETIC relationship A. Linnaeus based his classification on physical characteristics 7. Organisms that are more closely related have similar genetic makeup and therefore have a recent common ANCESTOR B. Modern scientists base classification on physical and chemical characteristics as well as fossil record Section 3: Kingdoms and Domains III. Problems in Classification A. As new evidence is discovered and new research is done scientists are having to reclassify organisms Bacteria: extremely small, single-celled organisms that usually have a cell wall and that usually reproduce by cell division: members of the domain Bacterial 6 3/29/17 Archaea: prokaryotes that are distinguished from other prokaryotes by differences in their genetics and in the makeup of their cell wall; members of the domain Archaea I. Updating Classification Systems A. When Linnaeus created his system he recognized two kingdoms: Eukaryote: an organisms made up of cells that have a nucleus enclosed by a membrane, multiple chromosomes, and a mitotic cycle; members of the domain Eukarya B. Biologists have added complexity and detail to classification systems as they have learned more 1. Many taxa have been proposed 1. Plantae 2. Animalia 2. Some have been reclassified C. 1800s added Kingdom Protista as a taxon for unicellular animals a. Sponges used to be classified as plants b. Microscopes allowed scientists to study sponge cells c. Scientists learned that sponge cells are much more like animal cells, so today sponges are classified as animals D. Then noticed differences between prokaryotic and eukaryotic cells 1. Scientists created Kingdom Monera for prokaryotes 7 3/29/17 E. By the 1950s, Kingdoms Monera, Protista, Fungi, Plantae, and Animalia were used F. In the 1990s, genetic data suggested two major groups of prokaryotes 1. Kingdom Monera split into Kingdoms II. The Three-Domain System A. Divide all organisms into three domains 1. Bacteria a. Eubacteria 2. Archaea b. Archaebacteria 3. Eukarya B. Major taxa are defined by major characteristics, including 1. Cell Type 2. Cell Walls a. Absent b. Present a. Prokaryotic 3. Body Type b. Eukaryotic a. Unicellular b. Multicellular 4. Nutrition a . Autotroph (makes own food) b. Heterotroph (gets nutrients from other organisms 5. Related groups of organisms have similar a. Genetic Material C. Bacteria 1. Prokaryotes 2. Strong exterior walls and a unique genetic system b. Systems of genetic expression 8 3/29/17 3. Same kind of cell membrane lipid as most eukaryotes do 5. Classified according to a. Their shape 4. All bacteria are similar in structure, no internal compartments b. Nature of their cell wall c. Their type of metabolism d. How they obtain nutrients 6. Most abundant organisms on Earth D. Archea 1. Chemically unique cell wall and membranes 7. Found in every environment 2. Unique genetic system a. Share some similarities with those of eukaryotes that they do not share with those of prokaryotes 3. Scientists think that archea evolved in a separate lineage from bacteria early in Earth’s history 4. Scientists also believe that some archea eventually gave rise to eukaryotes 5. First found in extreme environments a. Salt Lakes b. Deep ocean c. Hot springs that exceeded 100 °C d. These archaea are called extremophiles e. Methanogens live in oxygen-free environments 9 3/29/17 E. Eukarya is made up of Kingdoms 1. Protista 2. Fungi 3. Plantae 6. Cells have a complex inner structure that enabled cells to become larger than the earliest cells 7. Complex inner structure enabled the evolution of multicellular organisms 4. Animalia 5. Eukaryotes 8. True multicellularity and sexual reproduction 9. Major groups of eukaryotes are defined by 1. Number of cells F. Plantae 1. Almost all plants are autotrophs a. The process that makes food, photosynthesis, occurs in chloroplasts 2. Body organization 3. Types of nutrition 2. Cell wall is made of a rigid material called cellulose 3. More than 350,000 known species of plants exist G. Animalia 1. Multicellular heterotrohps 2. Their bodies may be simple collections of cells or complex networks of organ systems 10 3/29/17 3. Animal cells lack a rigid cell wall 4. More than 1 million known species of animals exist H. Fungi 1. Heterotrophs that are mostly multicellular 2. Cell wall is made of a rigid material called chitin 3. More than 70,000 known species of fungi exist I. Protista 1. A “leftover” taxon, it is a diverse group 2. Any eukaryote that is not a plant, animal, or fungi can be called a protist 3. Did not descend from a single common ancestor 4. Biologists recognize four major groups of protists: a. Flagellates b. Amoeba c. Algae d. Parasitic protists 5. Recently, biologists have proposed to replace Protista with several new kingdoms Natural Selection Review I. Define natural selection A. Survival and Reproduction of organisms best adapted to the environment 11 3/29/17 Use the table below to answer the following questions: B. List the four parts of natural selection 1. There is variation within populations 2. Some variations are favorable Level Kingdom Phylum Class Order Family Genus Species Dog Animalia Chordata Mammalia Carnivora Canidae Canis familiaris Wolf Animalia Chordata Mammalia Carnivora Canidae Canis lupus Human Animalia Chordata Mammalia Primate Hominidae Homo sapiens House Cat Animalia Chordata Mammalia Carnivora Felidae Felis domesticus Octopus Animalia Molluska Cephalopoda Octopoda Octopodidae Octopus vulgaris Anteater Animalia Chordata Mammalia Edentata Myrmecophagidae Myramecophaga tridactyla 3. Not all offspring survive 4. Individuals that survive & reproduce are those with favorable variations a. Which organisms on the table are most closely related? Dog - Wolf b. Which level of classification is your answer based on? Species c. Which organisms on the table is the most distantly related to the others? Octopus d. Which level of classification is your answer base on? Phylum 12