26.
Bacteria and Archaea: The Prokaryotic Domains 560
26.1
How Did the Living World Begin to
Diversify? 561
The three domains differ in significant
ways 561
26.2
Where Are Prokaryotes Found? 563
Prokaryotes generally form complex
communities 563
26.3
What Are Some Keys to the Success
of Prokaryotes? 565
Prokaryotes have distinctive cell
walls 565
Prokaryotes have distinctive modes
of locomotion 566
Prokaryotes reproduce asexually, but
genetic recombination can occur 566
Some prokaryotes communicate 566
Prokaryotes have amazingly diverse
metabolic pathways 567
26.4
How Can We Determine Prokaryote Phylogeny?
569
Size complicates the study of prokaryote
phylogeny 569
The nucleotide sequences of prokaryotes
reveal their evolutionary relationships
569
Lateral gene transfer may complicate
phylogenetic studies 570
The great majority of prokaryote species
have never been studied 570
Mutations are a major source of prokaryotic
variation 571
26.5 What Are the Major Known Groups
of Prokaryotes? 571
Spirochetes move by means of axial
filaments 571
Chlamydias are extremely small parasites
572
Some high-GC Gram-positives are valuable
sources of antibiotics 572
Cyanobacteria are important photoautotrophs
573
Not all low-GC Gram-positives are
Gram-positive 573
The Proteobacteria are a large and
diverse group 574
Archaea differ in several important
ways from bacteria 575
Many Crenarchaeota live in hot, acidic
places 576
The Euryarchaeota live in many surprising
places 577
Korarchaeota and Nanoarchaeota are
less well known 577
26.6
How Do Prokaryotes Affect Their Environments?
578
Prokaryotes are important players
in element cycling 578
Prokaryotes live on and in other organisms
579
A small minority of bacteria are pathogens
579
