PROKARYOTES

Organisms divided into 3 domains. Table 27.2 characteristics of 3 domains.

Domain Bacteria

     

Domain Archaea

Archaea vs. Bacteria

• Ribosomal RNA different
• Cell walls lack peptidoglycan which Bacteria cell walls have
• Membrane lipids with branched hydrocarbons which Bacteria do not have
• Archaea has more in common with Eukarya than with Bacteria

Structural Characteristics- Lack membrane-bound organelles and nuclear membrane. Fig. 7.4

Size Fig 18.1

Three shapes of prokaryotes (Fig 27.3)

Gram-positive vs. Gram-negative (Fig 27.5)

Structure of flagella (Fig 27.7)          Pili (Fig 27.6)

Special membranes (Fig 27.8)

Diversity of prokaryotes (Fig 27.13)

Types of metabolism (Table 27.1)

• Photoautotrophs - evolution of photosythesis (Fig 27.12)
• Chemoautotrophic
• Photoheterotrophic
• Chemoheterotrophic

     Saprobes

     Parasites

Oxygen relationships

• Obligate aerobes
• Obligate anaerobes
• Facultative anaerobes

Bacteria of ecological importance

• decomposers (Fig 27.18) - recycling nutrients
• symbiosis - symbiont, host, mutualism, commensalism, parasitism
• nitrogen fixation Fig 54.18
• cyanobacteria in aquatic systems - many with heterocysts in which they fix nitrogen (Fig 27.11)

Bacteria as Human Pathogens - a parasitic relationship

Examples: cholera, leprosy, tetanus, anthrax, Lyme disease, bacterial pneumonia, whooping cough, syphilis, gonorrhea, bubonic plague, (life cycle)

Methods of action of pathogenic bacteria

Endotoxins - examples: Salmonella and Escherichia

Exotoxins - examples: Clostridium and the bacteria that cause cholera and bubonic plague

Invade host's tissues - more rare than above - example: the actinomycete that causes tuberculosis

Get more information on diseases at the CDC.  

More than half of our antibiotics come from soil bacteria. Antibiotics do not work on viruses, but evolved as a method for some bacteria to be able to kill other bacteria - an extreme form of competition.