chapter 10

• classification


  process by which living organisms are sorted into groups, the organisms within each group share similar features
• taxonomic groups

  domain, kingdom, phylum, class, order, family, genus, species

  
• why do scientists classify organisms

  1. to identify species

  2. to predict characteristics

  3. to find evolutionary links
• three domains

  archaea, bacteria, eukarya
• going down the hierarchy


  more groups at each level but fewer organisms in each group, they are more similar and share more of the same characteristics
• species


  group of organisms that are able to reproduce to produce fertile offspring
• why are mules and hinnies infertile

  cells contain an odd number of chromosomes (63), so meiosis and gamete production cannot take place correctly, this number is created because horses have 64 chromosomes (32 pairs) and donkeys have 62 chromosomes (31 pairs)
• binomial nomenclature


  the system of nomenclature in which two terms are used to denote a species of living organism, the first one indicating the genus and the second the specific epithet.
• first part of name

  genus, similar to surname or family name, shared by close family
• second part of name

  species, called the specific name
• five kingdoms

  1. prokaryote

  2. protoctista

  3. fungi

  4. plantae

  5. animalia
• prokaryotes


  unicellular with no nucleus or membrane bound DNA, and no visible feeding mechanism
• prokaryote example

  E. coli
• protoctista


  mainly unicellular, has a nucleus and other membrane bound organelles and some have chloroplasts, can move by flagella and nutrients acquired by photosynthesis
• protoctista example

  amoeba
• fungi


  uni or multi cellular, normal cell structures with chitin cell wall, no chloroplasts, no locomotion, nutrients acquired by absorption and store food as glycogen
• fungi example

  mushrooms, yeast
• plantae


  multicellular, normal cell structures with a cellulose cell wall and chloroplasts, nutrients acquired by photosynthesis and store food as starch
• plantae example


  flowering plants, trees, moss, fern
• animalia


  multicellular, normal cell structure, move with cillia, flagella or muscles, nutrients acquired by ingestion, food stored as glycogen
• animalia example


  cats, birds, humans, sponges
• autotrophic feeders


  organisms that synthesis complex organic molecules from inorganic molecules via photosynthesis
• heterotrophic feeders


  organisms that acquire nutrients by the ingestion of others
• saphrophytic feeders


  organisms that acquire nutrients through absorption mainly of decaying material
• three domain system = 6 kingdoms

  developed in 1977 by Carl Woese, domains are a further level of classification at the top of the hierarchy, he grouped organisms in sequences of the nucleotides of DNA
• three domains

  1. archaea

  2. bacteria

  3. eukarya
• archaea

  have 70s ribosomes, RNA polymerase of different organisms contain 8-10 proteins and is very similar to eukaryotic ribosome
• bacteria

  have 70s ribosomes, RNA polmerase contains 5 proteins
• eukarya

  have 80s ribosomes, RNA polymerase contains 12 proteins
• RNA polymerase


  responsible for most mRNA transcription
• 2 prokaryote kingdoms

  Woese split prokayrote into 2 halves

  1. archaebacteria

  2. eubacteria
• archaebacteria

  ancient bacteria, can live in extreme environments e.g thermal vents, anaerobic conditions and highly acidic environments, e.e methanogens live in anaerobic conditions such as sewage treatment plants
• eubacteria


  true bacteria, found in all environments and are more common
• classification levels diagram

  
• phylogeny


  evolutionary relationships between organisms
• phylogenetics


  study of the history groups of organisms
• phylogenetic trees / evolutionary trees


  used to represent the evolutionary links between organisms, branched diagrams to show that different species have evolved from a common ancestor, produced by grouping by physical looks and genetic makeup

  
• advantages of phylogenetic classification

  can be done without reference to linnean system, and it has a continuous tree which is variable, hierarchy of linnean can be misleading in grouping
• evolution


  theory that describes the way in which organisms evolve or change over many many years as a result of natural selection
• darwin in 1831


  went on the HMS Beagle and carried out observations on finches in the Galapagos Islands, and noticed that finches on different islands had different beaks and claws with different shapes and sizes