domain or kingdoms?

• How did CARL LINNAEUS CLASSIFY LIVING ORGANISMS?

  based on visible features
• Molecular evidence - basic idea

  certain large biochemical molecules are found in all living organisms but are not identical in all living things

  DIFFERENCES REFLECT EVOLUTIONARY RELATIONSHIPS (PHYLOGENY)
• examples of biochemical molecules used in classification:

  haemoglobin

  DNA and RNA

  Cytochrome C - a small protein found in many species, used in the process of RESPIRATION
• Molecular evidence - DNA and proteins

  for PROTEINS, biologists would look at the amino acid sequence

  for DNA, biologists would look at the DNA base sequence for a SPECIFIC GENE

  if the AMINO ACID SEQUENCE/DNA NUCELOTIDE BASE SEQUENCE are the same, the species are closely related

  if the AMINO ACID SEQUENCE/DNA NUCLEOTIDE BASE SEQUENCE is different, the species are NOT so closely related
• what kingdom to PROKARYOTES belong to?

  PROKARYOTAE
• what kingdom do eukaryotes belong to?

  FUNGI

  PLANTAE

  PROTOCTISTA

  ANIMALIA
• Origin of the 3 domain system

  in 1977, Carl Woese developed a new classification system, dividing the kingdom PROKARYOTAE into:

  • Bacteria (eubacteria)
  • Archaea (archaebacteria)

  he based his ideas on the study of RIBOSOMAL RNA and the cell membrane lipid structure and sensitivity to antibiotics
• Molecular evidence for 3 DOMAIN SYSTEM

  RNA polymerase to make RNA is different in ARCHAEA and BACTERIA

  Archaea, unlike Bacteria, have histone proteins similar to EUKARYA
• Cell membrane evidence

  bonds of lipids in cell membranes different in Archaea and Bacteria

  development and composition of flagella is different

  sensitivity to antibiotics is different
• The MAIN EVIDENCE


  division is based on the fact that BACTERIA/EUBACTERIA is different to ARCHAEA/ARCHAEBACTERIA and EUKARYOTAE

  (eu)bacteria have different cell membrane structure, different flagella structure, different RNA polymerase and cell wall made of peptidoglycan not found in Archaebacteria

  
  

  Archaea and Eukaryota share some of the same features:

  • similar membrane structure
  • similar RNA polymerase
  • PROTEINS THAT BIND TO DNA (histones)
  • similar mechanisms to build DNA and RNA

  archaea are more closely related to eukaryota than bacteria
• comparing RNA polymerase


  Bacteria: contains 5 proteins

  Eukaryota: contains 12 proteins

  Archaea: contains 8-10 proteins
• comparing eubacteria and archaebacteria

  ARCHAEBACTERIA:

  • known as ancient bacteria
  • live in extreme conditions - hot thermal vent, highly acidic environments

  EUBACTERIA:

  • known as true bacteria
  • most bacteria belongs to this group
• what feature does Archaebacteria share with humans?

  no peptidoglycan cell wall
• draw evolutionary tree of bacteria, archaea and eubacteria

  there is a common ancestor for Archaea and Eukaryotes more closely related than the common ancestor for Eukaryotes, Archaea and Eubacteria

  A) not this one

  B) not this one

  C) not this one

  D) not this one

  
• summary of 3 domain system

  more ACCURATELY reflects the ORIGINS of eukaryotes and prokaryotes

  divides prokaryotes

  reflects differences between bacteria and archaea

  groups eukaryotes together

  reflects differences between eukaryotic kingdoms
• what is prokaryotae divided into

  archaea

  bacteria
• what is eukaryota divided into

  fungi

  animalia

  plantae

  protoctista
• how is SIX KINGDOMS formed?

  combining five kingdom and 3 domain system
• what are the CHARACTERISTICS of a six kingdom system?

  separates prokaryotes into EUBACTERIA and ARCHAEABACTERIA

  keeping eukaryotic kingdoms separate

  having DOMAIN as a FURTHER LEVEL OF CLASSIFICATION at the top of th hierarchy
• what are the SIX KINGDOMS?

  Animalia, Plantae, Fungi, Protoctista

  Archaea, Bacteria (formally prokaryotae)
• why is the 3 domain system used nowadays?

  3 domains fits PHYLOGENY better

  there are key differences between eubacteria and archaebacteria (membrane structure, flagella structure, RNA polymerase, cell wall made of peptidoglycan)

  differences between prokaryotes and eukaryotes

  eukaryotes have NUCLEUS