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CLASSIFICATION How can you classify fruits? Procedure 1. 2. 3. 4. Obtain five different fruits. Use a paring knife to cut each fruit open and examine its structure. CAUTION: Use caution with sharp instruments. Construct a table with five rows and four columns. Label each row with the name of a different fruit. Observe each fruit and choose four characteristics by which you can tell the fruits apart. Label the columns in your table with these four characteristics. Record a description of each fruit in your table. Think About It 1. 2. I. Observing What characteristics did you use to describe the fruits? Classifying Based on your table, which fruits are most closely related? Explain. Finding order in diversity - scientists named 2.5 million species - estimated 4-30 million additional species yet to be discovered i. Why classify 1. To avoid confusion caused by common names, biologists assign each species a scientific name 2. To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner 3. Taxonomy – ii. Assigning scientific names 1. ______________________________ a. Each species is assigned a two-part scientific name b. Written in italics, first word is capitalized, second is lower case i. Ex. Grizzly bear Ursus arctos 1. Ursus – 2. arctos – a. there are 5 other types of bears in the same genus Ursus iii. Linnaeus’s systen of classification 1. Taxon – i. Linnaeus’s system of classification uses seven taxonomic categories. They are – from smallest to largest – species, genus, family, order, class, phylum and kingdom ii. Figure 18-5 SECTION ASSESMENT 1. Key Concept How are living things organized for study? 2. Key Concept Describe the system for naming species that Linnaeus developed. 3. Key Concept What are the seven taxonomic categories of Linnaeus’s classification system? 4. Why do scientists avoid using common names when discussing organisms? 5. Critical Thinking Applying Concepts Which category has more biological meaning—all brown birds or all hawklike birds? Why? II. MODERN EVOLUTIONARY CLASSIFICATION i. Problems with traditional classification 1. vultures american, african and asian a. american habit of urinating on legs to cool themselves, same as storks. African and asian vultures do not. ii. Evolutionary classification Overhead of humans and apes 1. guided by evolutionary theory, biologists new group organisms into categories that represent lines of evolutionary descent, not just physical similarities 2. _______________________ – method of grouping organisms according to how recently descended they are from a common ancestor. 3. traditional classification – figure 18-7 4. Classification using cladograms a. Cladistic analysis identifies and considers only characteristics that are evolutionary innovations, new characteristics that arise as lineages evolve over time b. ______________________ – unique features that appear in some organisms but not others c. __________________ – branching diagram used to show the diverging sequence in which key evolutionary changes occurred QUICK LAB PG. 453 How is a cladogram constructed? Procedure 1. 2. Identify the organism in the table that is least closely related to the others. Use the information in the table to construct a cladogram of these animals. Analyze and Conclude 1. Analyzing Data What trait separates the least closely related organism from the other animals? 2. Classifying List the animals in your cladogram in order of distance from the least closely related organism. 3. Drawing Conclusions Does your cladogram indicate that lizards and humans share a more recent common ancestor than either does with an earthworm? Explain. 4. Inferring Where would you insert a frog if you added it to the cladogram? Explain your answer. iii. Similarities in RNA and DNA 1. all living organisms use RNA and DNA the same way 2. Common ancetry evident in genes a. The genes of many dissimilar organisms show important similarities at the molecular level. These similarities can be used as critieria for classification b. Common gene structure indicator of common ancestory i. Similar common feature of all living cells – the ribosome – the cellular “protein factor”. ii. Gene that codes for myosin found in muscles in humans intercellular parts to move in yeast iv. Molecular clocks 1. molecular clock – model used to estimate the length of time that 2 species have been evolving independantly based on mutations in an organisms DNA Section assesment 1-5 pg. 455 1. Key Concept How is information about evolutionary relationships useful in classification? Key Concept How are genes used to help scientists classify organisms? 2. 3. What is the principle behind cladistic analysis? 4. Describe the relationship between evolutionary time and the similarity of genes in two species. 5. Critical Thinking Applying Concepts How have new discoveries in molecular biology affected the way in which we classify organisms compared with the system used by Linnaeus? Constructing a Chart Draw a cladogram of a manufactured item, such as an automobile or a household item, that has changed over the years. Label derived characters that appeared as new models arose. For example, automobiles came to have electronic fuel injection and antilock brakes. III. Kingdoms and Domains i. The tree of life evolves 1. in the beginning…… then……. The six kingdom system of classification includes the kingdoms ANIMALIA, PLANTAE, FUNGI, PROTISTA, AND 2 BACTERIAL KINGDOMS EUBACTERIA AND ARCHAEBACTERIA. ii. The 3 domain system 1. ______ – is a more inclusive category than any other – larger than a kingdom. 2. The three domains are: the domain of bacteria, which corresponds to the kingdom ________________; the domain archae, which corresponds to the kingdom __________________; and the domain ____________, which is composed of animals, plants, fungi, and protists. CLASSIFICATION OF LIVING THINGS DOMAIN KINGDOM CELL TYPE NUMBER OF CELLS MODE OF NUTRITION EXAMPLES 3. Bacteria a. Domain of unicellular prokaryotes that have cell walls containing peptidoglycans 4. Archaea a. Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycans 5. Eukarya a. Domain of all organisms whose cells have nuclei, including protists, plants, fungi and animals i. Protistsa – kingdom composed mainly of single – celled eukaryotes: includes all eukaryotes that are not classified as plants, animals or fungi ii. Plantae – kingdom of multicellular photosynthetic autotrophs that have cell walls containing cellulose iii. Fungi – kingdom composed mainly of saprophytes, which obtain energy and nutrients from dead and organic matter iv. Animalia – kingdom of multicellular eukaryotic heterotrophs whose cells do not have cell walls Section assesment 1-3, 5 1. Key Concept What are the six kingdoms of life as they are now identified? 2. Key Concept What are the three domains of life? 3. Why was the kingdom Monera divided into two separate kingdoms? 4. Why might kingdom Protista be thought of as the “odds and ends” kingdom? 5. Critical Thinking Classifying Which kingdoms include only prokaryotes? Which kingdoms include only heterotrophs?