evolution and diversity of microbes

Cards (49)

  • What are prokaryotes?
    Single-celled organisms without a nucleus
  • How long did prokaryotes dominate Earth?
    3,000 million years
  • What significant environmental changes did prokaryotes cause?
    Oxygenation of the atmosphere
  • What happened to ocean depths due to prokaryotes?
    Suffocation with hydrogen sulphide
  • What global event was precipitated by prokaryotes?
    Global freeze
  • How did prokaryotes change over time?
    Changed very little themselves
  • What is the lifestyle of prokaryotes when resources are unavailable?
    Remain in stasis
  • What happens to prokaryotes when resources become available?
    Divide extremely rapidly
  • What limits the rate of cell division in prokaryotes?
    Rate of DNA replication
  • What is selected for when resources are scarce?
    Best survivors
  • What is selected for when resources are plentiful?
    Best dispersers
  • What is the limit on prokaryote genome size?
    10 million base pairs
  • How do larger genomes affect prokaryotes?
    Reduce replication rate, increase versatility
  • Where are larger genomes favored?
    Where resources are scarce and diverse
  • What happens to excess genes in prokaryotes?
    Eliminated rapidly by natural selection
  • What do prokaryotes tend to lose?
    Genes not required immediately
  • How can prokaryotes acquire new genes?
    From living cells through conjugation
  • What is the role of core genes in prokaryote phylogenetics?
    Inherited vertically from parents
  • What do lateral genes form in prokaryotes?
    Network of gene exchange
  • How do distant prokaryotes exchange DNA?
    Through horizontal transfer
  • What complicates the species concept in prokaryotes?
    Horizontal gene transfer among distantly related
  • What does the quote “If a bacterium can find an electron, it will steal it” imply?
    Prokaryotes are opportunistic in metabolism
  • What does Hydrogenobaculum oxidise?
    Hydrogen
  • What does Gallionella oxidise?
    Iron
  • Where can prokaryotes survive?
    In extreme environments like hydrothermal vents
  • What is Strain 121 known for?
    Metabolising at 121°C
  • What happens to Strain 121 at 130°C?
    Goes dormant
  • What does Sulfolobus oxidise?
    Hydrogen sulphide and sulphur
  • What is the pH of water acidified by Sulfolobus?
    pH 2
  • What event caused the exclusion of anaerobes from much of Earth?
    Great oxygenation event
  • Where do methanogens survive?
    In oxygen and sulphate absent environments
  • What do methanogens produce?
    Methane gas
  • What do anaerobes do in the presence of oxygen?
    Unable to metabolise
  • How do prokaryotes reduce competition?
    By diversifying metabolism
  • What do prokaryote communities form?
    Mutually beneficial associations
  • What are stromatolites?
    Fossils formed by bacterial communities
  • How old are the oldest stromatolites?
    3.5 billion years old
  • What shapes do stromatolites form?
    Fingers, fists, cauliflowers, and more
  • What caused the decline of stromatolites?
    Evolution of grazing animals
  • Where are present-day stromatolites restricted to?
    Protected habitats with low nutrients