chapter 10 characterizing and classifying prokaryotes 10/1/11mdufilho1

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Chapter 10

Characterizing and Classifying

Prokaryotes

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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

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Figure 11.1 Typical prokaryotic morphologies

Coccus

Coccobacillus

Bacillus

Vibrio

Spirillum

Spirochete

Pleomorphic

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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

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Figure 11.6 Arrangements of cocci-overview

Figure 11.7 Arrangements of bacilli-overview

General Characteristics of Prokaryotic Organisms

• Reproduction of Prokaryotic Cells– All reproduce asexually

– Three main methods– Binary fission (most common)– Snapping division– Budding

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Figure 11.2 Binary fission

Cell replicates its DNA.

Nucleoid

Cell wallCytoplasmicmembraneReplicatedDNA

The cytoplasmicmembrane elongates,separating DNAmolecules.

Cross wall forms;membraneinvaginates.

Cross wall formscompletely.

Daughter cellsmay separate.

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Figure 11.3 Snapping division-overview

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Figure 11.4 Actinomycetes spores

Spores

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Figure 11.5 Budding

DNA is replicated

One daughter DNAmolecule is movedinto bud

Young bud

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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

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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

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Figure 11.9 Prokaryotic taxonomy

PHYLUM CHLOROFLEXI(green nonsulfur)

Thermophilicbacteria

PHYLUM DEINOCOCCUS-THERMUS

Deeply branching bacteria

PHYLUM AQUIFICAE

GRAM-NEGATIVE BACTERIA

PHYLUM PROTEOBACTERIA

Rickettsias ()Rhodospirilla ()

(purple nonsulfur)

Rhizobium ()

Nitrifying ()

Myzobacteria ()

Campylobacteria ()

Pseudomonads ()

PHYLUMCHLOROBI(green sulfur)

Neisserias ()

PHYLUMBACTEROIDETES

PHYLUM FIBROBACTERES

PHYLUM CHLAMYDIAE

PHYLUM SPIROCHAETESPHYLUMPLANCTOMYCETES

PHYLUM CYANOBACTERIA

BACTERIA

ARCHAEA

PHYLUM FUSOBACTERIAPHYLUM FIRMICUTESClostridia

Mycoplasmas

Bacilli-Lactobacilli

Arthrobacter

Streptomyces

AtopobiumCorynebacteriumMycobacteriumNocardia

PHYLUM ACTINOBACTERIA

GRAM-POSITIVE BACTERIA High G+C Gram-positive

PHYLUM KORARCHAEOTA

PHYLUM EURYARCHAEOTA

PHYLUMCRENARCHAEOTA

Thermophilicarchaea

Methanogens

Halophiles

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