Bacteria, Archaea and a mention of Viruses.
  • Bacteria and Archaea
    1. Archaea used to be a subgroup of Bacteria
      1. distinguishing characters on pg. 485
      1. Molecular phylogenies place Archaea and Eukarya as sister groups
      2. Lateral gene transfer confounds construction of phylogenies
        1. different phylogenies from different gene groups
    2. metabolic diversity
      1. sources of Carbon
        1. autotrophs vs. heterotrophs
      2. sources of energy
        1. light, reduced organic compounds, reduced inorganic compounds
        2. in all cases, the organism is converting energy to ATP through an electron transport chain
    3. Environmental roles
      1. oxygen revolution
        1. free molecular oxygen introduced by early prokaryotes
      2. Nitrogen fixation
        1. many different lineages
        2. some free-living, some symbiotic in plants
      3. Eutrification of lakes
        1. "algal" blooms are actually bacteria and algae
        2. rapid population growth due to nitrate (NO3-) pollution
  • Viruses
    1. are they "living"?
      1. are not cells
      2. cannot replicate themselves, obtain energy, synthesize organic compounds
    2. structure
      1. genome: DNA or RNA, single or double-stranded
      2. capsid
      3. envelope (not always present)
    3. replication always requires parasitism
      1. hosts range from Archaea to Eukaryotes
      2. viruses with RNA genomes have reverse transcriptase
      3. infection may result in lytic growth or lysogenic growth
    Study questions
    1.  What is lateral gene transfer, and how could it influence ability to reconstruct evolutionary relationships?
    2.  What is the possible significance of the different phylogenies that are derived from gene sequences obtained from metabolic pathways vs. "information processing" pathways?
    3.  Speculate on the importance of the prokaryotic "oxygen revolution" in the evolution of the Protista.
    4.  There is a "dead zone" in the Gulf of Mexico off the coast of Louisiana.  Trace the chain of chemicals resulting in this anaerobic area (in very general terms).
    5.  Viruses are not considered to be living, but they can evolve.  How does this affect your understanding of "living" and "evolution"?
    6.  What is the (theoretical) relationship between virulence and transmission of disease-causing organisms?
    7. Why has HIV been exceedingly difficult to treat?

    Answers