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Characterizing and Classifying Prokaryotes
Chapter 10 Characterizing and Classifying Prokaryotes 10/1/11 MDufilho
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General Characteristics of Prokaryotic Organisms
Prokaryotes Most diverse group of cellular microbes Habitats From Antarctic glaciers to thermal hot springs From colons of animals to cytoplasm of other prokaryotes From distilled water to supersaturated brine From disinfectant solutions to basalt rocks Only a few capable of colonizing humans and causing disease 10/1/11 MDufilho 2
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Figure 11.1 Typical prokaryotic morphologies
Coccus Spirillum Coccobacillus Spirochete Bacillus Pleomorphic Vibrio 10/1/11 MDufilho
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General Characteristics of Prokaryotic Organisms
Arrangement of Prokaryotic Cells Result from two aspects of division during binary fission Planes in which cells divide Separation of daughter cells © 2012 Pearson Education Inc. 4
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Figure 11.6 Arrangements of cocci-overview
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Figure 11.7 Arrangements of bacilli-overview
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General Characteristics of Prokaryotic Organisms
Reproduction of Prokaryotic Cells All reproduce asexually Three main methods Binary fission (most common) Snapping division Budding 10/1/11 MDufilho 7
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10/1/11 MDufilho Cell replicates its DNA. Cell wall
Figure Binary fission Cell replicates its DNA. Cell wall Cytoplasmic membrane Nucleoid Replicated DNA The cytoplasmic membrane elongates, separating DNA molecules. Cross wall forms; membrane invaginates. Cross wall forms completely. Daughter cells may separate. 10/1/11 MDufilho
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Figure 11.3 Snapping division-overview
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Figure 11.4 Actinomycetes spores
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One daughter DNA molecule is moved into bud
Figure Budding DNA is replicated One daughter DNA molecule is moved into bud Young bud Daughter cell 10/1/11 MDufilho
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Figure 11.6 Arrangements of cocci-overview
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Figure 11.7 Arrangements of bacilli-overview
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General Characteristics of Prokaryotic Organisms
Endospores Produced by Gram-positive Bacillus and Clostridium Each vegetative cell transforms into one endospore Each endospore germinates to form one vegetative cell Defensive strategy against unfavorable conditions Concern to food processors, health care professionals, and governments 10/1/11 MDufilho 14
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Figure 11.8 Locations of endospores-overview
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Modern Prokaryotic Classification
Currently based on genetic relatedness of rRNA sequences Three domains Archaea Bacteria Eukarya 10/1/11 MDufilho . 16
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Figure 11.9 Prokaryotic taxonomy
BACTERIA PHYLUM CHLOROFLEXI (green nonsulfur) Thermophilic bacteria PHYLUM DEINOCOCCUS-THERMUS Deeply branching bacteria GRAM-NEGATIVE BACTERIA PHYLUM PROTEOBACTERIA PHYLUM AQUIFICAE Rhodospirilla () (purple nonsulfur) Rickettsias () Nitrifying () Rhizobium () Myzobacteria () PHYLUM CHLOROBI (green sulfur) Campylobacteria () Pseudomonads () Neisserias () PHYLUM CYANOBACTERIA PHYLUM KORARCHAEOTA PHYLUM FIBROBACTERES PHYLUM BACTEROIDETES PHYLUM CHLAMYDIAE PHYLUM PLANCTOMYCETES PHYLUM SPIROCHAETES ARCHAEA PHYLUM EURYARCHAEOTA Methanogens PHYLUM CRENARCHAEOTA PHYLUM FIRMICUTES PHYLUM FUSOBACTERIA Clostridia Halophiles Mycoplasmas Bacilli-Lactobacilli Streptomyces Atopobium Arthrobacter Corynebacterium Mycobacterium Nocardia Thermophilic archaea PHYLUM ACTINOBACTERIA 10/1/11 MDufilho GRAM-POSITIVE BACTERIA High G+C Gram-positive
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