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Biology - Chp 18 - Classification - PowerPoint
This chapter discusses the classification of organisms into a taxonomic system. It describes how Carolus Linnaeus developed the binomial nomenclature system of scientific naming that is still used today. The chapter also explains how modern evolutionary classification uses cladograms and molecular evidence like DNA comparisons to group organisms based on lines of evolutionary descent rather than just physical similarities. Finally, it outlines the three domain system of classification, separating all living things into the domains of Archaea, Bacteria, and Eukarya.
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Biology - Chp 18 - Classification - PowerPoint
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- 3. 18 – 1Finding Order in Diversity
- 4. • Evolution haslead to a staggering variety or organisms • Biologists have identified and named about 1.5 million species so far • They estimate anywhere between 2 and 100 million additional species have yet to be discovered
- 5. Taxonomy • The scienceof classifying and naming organisms
- 6. Assigning Scientific Names •By the 18th century, European scientists recognized that referring to organisms by common names was confusing • Common names vary among regions within a country
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- 11. Early Efforts atNaming Organisms • First attempts at standard scientific names often described physical characteristics • As a result, these names could be 20 words long! • Ex.) The English translation of the scientific name of a particular tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.”
- 12. Binomial Nomenclature • CarolusLinnaeus (18th Century) • Swedish Botanist • Developed a system for naming organisms
- 13. Binomial Nomenclature • Twoword naming system
- 14. Rules for Binomial Nomenclature • Written in italics • First word is capitalized • Second word is lowercased Ex.) Genus species Genus species G. species
- 15. • The nameoften tells you something about the species • Ex.) Tyranosaurus Rex • Tyrant Lizard King
- 17. Taxon (taxonomic category) •A group or level of organization
- 19. Linnaeus’s system ofclassification uses seven taxonomic categories Largest / Least Kingdom Specific Phylum Class Order Family Genus Smallest / Most Specific species
- 20. Mnemonic Device Kingdom • King Phylum • Phillip Class • Came Order • Over Family • For Genus • Good species • Soup
- 22. 18 -2 ModernEvolutionary Classification
- 23. Problems with TraditionalClassification • Sometimes, due to convergent Evolution organisms that are quite different from each other evolve similar body structures • Ex.) Crab, limpet, barnacle
- 25. Evolutionary Classification • Darwin’stheory of evolution changed the entire way that biologists thought about classification • Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities
- 26. Classification Using Cladograms • Many biologists now prefer a method called cladistic analysis • This method of classification identifies and considers only those characteristics that arise as lineages evolve over time
- 27. Derived characteristics • Characteristicsthat appear in recent parts of a lineage but not in its older members
- 28. Cladograms • Diagram thatshows the evolutionary relationships among a group of organisms
- 30. Similarities in DNAand RNA • Suppose you were trying to compare diverse organisms such as yeast and humans • It wouldn’t make sense to try to classify anatomical similarities • The genes of many organisms show important similarities at the molecular level • These similarities can be used as criteria to help determine classification • Ex.) Myosin in humans & yeast
- 31. Molecular Clocks • UseDNA comparison to estimate the length of time that two species have been evolving independently
- 32. Molecular Clocks • Mutationshappen all the time at about the same rate • A comparison of DNA sequences in two species can reveal how dissimilar the genes are • The degree of dissimilarity is an indication of how long ago the two species shared a common ancestor
- 34. 18 -3 Kingdomsand Domains
- 35. • In taxonomy,as in all areas of science, ideas and models change as new information arises, some explanations have been discarded altogether, whereas others such as Darwin’s theory of evolution by natural selection, have been upheld • So it should not be surprising that since the 1800’s, the tree of life has been revised and edited since the discovery of all this new information
- 36. The Tree ofLife Evolves • Before Linnaeus’s time, the only two Kingdoms that existed were Plants and Animals • As scientists discovered new organisms that didn’t fit into the plant or animal category, they made a new category
- 37. The Old 5Kingdom System 1. Animals 2. Plants 3. Fungi 4. Protist 5. Bacteria
- 38. • In recentyears, as evidence about microorganisms continued to accumulate, biologists come to recognize that the Monera were composed of two distinct groups
- 39. The New 6Kingdom System 1. Animals 2. Plants 3. Fungi 4. Protist 5. Eubacteria 6. Archaebacteria
- 41. The Three DomainSystem • Molecular analysis has given rise to a new taxonomic category that is now recognized by many scientists
- 42. Domain • Larger thana kingdom
- 43. 3 Domains 1. Bacteria •Eubacteria 2. Archaea • Archaebacteria 3. Eukarya • Protists, fungi, plants, animals (Everything with a nucleus)
- 44. Domain Bacteria • Unicellular •Prokaryotic - no nucleus, no membrane bound organelles • Thick walls (containing peptigoglycan) • Free living and parasitic • Important decomposers • Some photosynthesize • Some don’t need oxygen – Anerobic • Some need oxygen – Aerobic
- 48. Agar Bacteria Colonies Petri dish
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- 51. Domain Archaea •Unicellular •Small •Prokaryotic •Live inextreme environments Ex.) volcanic hotsprings, brine pools, black organic mud without oxygen
- 52. • Acidophiles –live in acidic environments • Thermophiles – can tolerate hot temperatures 50 – 110 degrees • Halophiles – can stand extreme concentrations of NaCl • Methanogens – Produce methane CO2 + H CH4
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- 56. Domain Eukarya • Consistsof all organisms that have a nucleus
- 57. Protista • Small • Mostlyunicellular • Eukaryotic – has a nucleus, and membrane bound organelles • Cannot be classified as animals, plants or fungi, but share many characteristics with plants, animals and fungi
- 58. Plant like Protists •Algae • Photosynthetic – can make their own food
- 59. Euglenas Flagella
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- 66. Animal like Protists •Protozoans • Heterotrophic – can’t make their own food
- 70. Fungus like Protists •Slime molds, water molds • Decompose their food
- 72. Fungi • Mostly multicellular Ex.)Mushroom, yeast • Cell walls
- 73. Fungi • Heterotrophs • Feedon decaying organic matter • Secrete digestive enzymes into food source then • Spread and reproduce by spores
- 74. Spores • Reproductive cellsthat form new organisms without fertilization
- 75. Many are usedin medicine • Antibiotics • Anti rejection • Anti viral
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- 77. Plantae • Multicellular • Photosyntheticautotrophs – make their own food by photosynthesis • Non-motile • Cell walls (cellulose)
- 78. Animalia • Multicellular • Heterotrophic • No cell walls • Most move • Incredible diversity