Three Domains Archaea- Very primitive Bacteria (formerly Eubacteria)- More advanced Eukarya- All life forms containing Eukaryotic cells (have a nucleus)
Ribosomal RNA and Classification rRNA is found in all cells rRNA is easy to isolate analyzed to determine the exact sequence of nucleotide bases The bases are a complementary copy of DNA Can be compared by the use of computers and statistics
Reclassification Several differences were found between Archaea and Bacteria which led to reclassification. –The major reason was due to differences in the genes that transcribe rRNA: Specific SSU rRNA sequences are found in archaea and not in bacteria. See next two slides for specific differences.
Ribosome Size: Archea and bacteria: 70S Eukarya: 80S
Diversity of Bacteria Cell Wall Structure: Gram Negative: –2 membranes less Peptidoglycan and are structurally more complex with an outer membrane (contains lipopolysaccharides) Gram Positive: –1 membrane, simpler walls, large amount of peptidoglycan.
Aggregates Vibrio Fischeri is an example of a bacteria that forms aggregates that show characteristics not seen in individual bacteria: Single individuals do not emit light unless they become part of a population with a high density V. fischeri releases a regulatory substance into its surroundings In dense populations, the concentration of the substance becomes high enough to trigger bioluminescence Happens when V. fischeriare living in mucus matrix in a squid
Gram Negative v. Gram Positive Gram Positive: Simple, one-cell membrane Several layer of peptidoglycan No outer membrane Gram Negative: Complex cell wall Small amount of peptidoglycan Thin peptidoglycan layer Inner and outer membrane with peptidoglycan in between
Virus Structure Diversity Capsid: Naked Capsid - no membrane/envelope outside protein coat Enveloped Capsid - cell membrane from host surrounds protein coat Genetic Material: DNA (double or single stranded) or RNA (double or single stranded)
OrganismNutritionLocomotionCell Wall Chlorop lasts Cillia or Flagellum Saccharomy ces heterotroph (extracellular digestion)absentmade of chitinabsent Amoeba heterotroph (intracellular digestion) slides using pseudopodia (amoeboid movements)absent Plasmodium heterotroph (intracellular digestion)glides on substrateabsent Paramecium heterotroph (intracellular digestion)swimming (cilia)absent cillia Euglenaautotroph and heterotrophswimming (flagella)absentpresentflagellum Chlorellaautotrophnone made of cellulosepresentabsent Diversity of Microscopic Eukaryotes