1

EUBACTERIA(Bacteria)

ARCHAEBACTERIA(Archaea)

EUKARYOTES(Eukarya)

The Prokaryotes

• Only two groups

• Archaebacteria and Eubacteria

• Arose before the eukaryotes

Prokaryotes—characteristics

• Single-celled

• Metabolically diverse

• No nuclear membrane

• Single chromosome

• No organelles

• Very small

• Cell wall

• Flagella rotate like propellers

• Pili extend from the cell surface for

adhesion or motion

Ecological Importance of

Prokaryotes

• Decomposition

• Nitrogen fixation

• Mutualistic relationships

• Parasitic relationships

• Commercial usesTreponema pallidum, a spiral-shaped bacteria which causes Syphilis in humans

Bacteria—what do they look

like?

Rods, spheres, spirals, vibrio

Fig. 21-5, p.335

Prokaryotic Fission

2

Bacterial Diversity

• Photoautotrophic

– Aerobic (Cyanobacteria)

– Anaerobic (Green bacteria)

• Chemoautotrophic

– Important in nitrogen cycle

• Chemoheterotrophic

– Largest group

• Bacteria, often in combination with yeasts

and molds, are used in the preparation of fermented foods such as:

– cheese, pickles, soy sauce, sauerkraut,

vinegar, wine, and yogurt.

• Bacteria are also important to numerous industrial processes,

– wastewater treatment

– industrial production of antibiotics and other chemicals.

• Some bacteria act as pathogens

– tetanus, typhoid fever, pneumonia, syphilis, cholera, food-borne illness, leprosy, and

tuberculosis(TB).

– In plants, bacteria cause leaf spot, fireblight, and wilts.

– The mode of infection includes contact, air, food, water, and insect-borne microorganisms

EUBACTERIA(Bacteria)

ARCHAEBACTERIA(Archaea)

EUKARYOTES(Eukarya)

Archaebacteria

Methanogens

Extreme halophiles

Extreme thermophiles

Fig. 21-11b, p.340

MethanogensMethanogens

3

Fig. 21-12a, p.341

Extreme HalophilesExtreme Halophiles

Fig. 21-12b, p.341

Extreme ThermophilesExtreme Thermophiles

Where Do Viruses Fit?

• Not “alive”?

• Not a cell

• Nucleic acids in protein shell

• Do not grow, do not maintain

homeostasis, and do not metabolize on their own

• Use host cell to replicate

• Lytic and Lysogenic life cycles

Early Stage of Influenza Virus

Viruses• Chicken pox

• H1N1

• Hepatitis

• HIV - human immunodeficiency virus

• Measles

• Mononucleosis

• Mumps

• Respiratory Syndrome (SARS)

• Smallpox

Why don’t antibiotics work for

colds and flu?

Why don’t they destroy your

body’s cells?

Hint: Antibiotics often work by

disrupting the bacteria cell wall.