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2.3: Cellular pathogens and hosts: prokaryotes and eukaryotes

Cellular pathogens and hosts: prokaryotes and eukaryotes

Unity and Diversity of Cellular Life

 For cellular organisms, Carl Woese developed the taxonomic level of “Domain” based on ribosomal RNA sequences


-In Belk’s Biology, see the “Tree of Life” fig 2.19 on page 47 which illustrates how all cellular organisms evolved from common ancestral prokaryotic organisms.

-This common ancestry explains the unity of life (why all cellular organisms share many processes and structures).

-Evolution explains the great diversity of life (see chapter __ “Microbial Genetics” of the Reader for more info on genetic diversity)

Cellular organisms: prokaryotes and eukaryotes


1. Prokaryote: unicellular organisms which lack membrane bound nucleus and other membrane-bound organelles (no nucleus; unicellular= 1 cell). See fig 2.17 p 41 in Belk’s Biology

-2 Domains of prokaryotic organisms


-Domain Archaea : few pathogens (maybe??)


                                -Domain Bacteria: contains the bacterial pathogens

e.g. Yersinia pestis/Bubonic Plague, Staphylococcus aureus/MRSA, Mycobacterium tuberculosis/TB, E. coli O157:H7, Bacillus anthracis/anthrax   


-can treat bacterial pathogens with antibioticx