classification and evolution

• classification


  the process by which organisms are sorted into groups
• why classify organisms 


  easier to identify

  makes study of living organism more manageable

  predict characteristics

  find evolutionary relationships

  convenience
• what are the 8 taxonomic groups

  domain

  kingdom

  phylum

  class

  order

  family

  genus

  species
• domain


  archaea, eubacteria, eukaryotae
• kingdom


  plantae, animalia, fungi, protoctista, prokaryotae
• phylum


  contains all teh groups of organisms that have same body plan
• class


  same general traits
• order


  additional info
• family


  closely related genera
• genus


  closely related species
• species


  some variation but all essentially the same
• naming organisms

  binomial system

  • common all around world
  • avoids confusion
  • genus first then species
• examples of prokaryotes


  bacteria, cyanobacteria
• features of prokaryotes


  unicellular

  no nucleus

  peptidoglycan cell wall

  no membrane bound organelles
• examples of protoctista


  paramecium, amoeba
• features of protoctista


  eukaryotic

  most are single celled

  some multi e.g algae

  plant and animal like features

  free living

  autotrophic and heterotrophic
• examples of fungi

  mushrooms, moulds, yeast
• features of fungi


  eukaryotic

  multi or unicellular

  body consist of mycelium -> network of hyphae

  cytoplasm surrounded by chitin

  many nuclei

  free living and saprophytic

  no chloroplasts
• examples of plantae 


  roses, oak trees, grasses
• features of plantae


  multicellular eukaryotes

  cellulose cell wall

  autotrophs

  contain chlorophyll

  store food as starch
• examples of animalia 


  cats, insects, sponges, lizards
• features of animalia 


  multicellular eukaryotes

  heterotrophs

  no cell walls or chloroplasts
• original classification


  based on observable characteristics
• convergent evolution


  different species may have adapted in similar ways to environment so look similar
• modern classification 


  basef on physiology, biochemsitry and genetic information e.g cytochrome C, DNA
• cytochrome C


  protein used in respiration

  not the same in all species

  more similarities = more closely related
• DNA


  more differences in bases indicates species have evolved separately for a long time
• eukarya/eukaryotae

  80s ribosomes

  RNA polymerase - 12 proteins
• archaea

  70s ribosomes

  RNA polymerase - 8-10 proteins
• bacteria

  70s ribosomes

  RNA polymerase - 5 proteins

  peptidoglycan cell wall
• how do bacteria differ from eukaryotes

  different flagella structure

  different enzymes for synthesising RNA

  naked DNA

  different methods of DNA replication

  different membrane structure

  70s ribosomes
• sharec features of archaea and eukaryotes


  similar enzymes to build RNA

  similar method of DNA replication

  both have proteins bound to DNA
• artificial classification


  based on a few characteristics

  does not reflect evolutionary relationships

  provides limited information

  stable
• natural classification 


  uses many characteristics

  reflects evolutionary relationships

  provides lots of info

  may change with advancing knowledge
• phylogeny 


  study of evolutionary relationships between species
• what does the top of branches show on a phylogeny tree

  most recent species
• what does the nodes of branches show on phylogeny tree

  common ancestors
• Darwin


  saw variation between individuals on different islands

  proposed mechanism of natural selection
• Wallace 


  same conclusions as Darwin

  Amazon and south east Asia
• Darwins 4 observations 


  offspring generally appear similar to parents

  organisms within species have variety

  all organisms overproduce more offspring than required to keep population steady

  population numbers remain the steady over long periods of time