BacteriaSection 18.2

Diversity of Prokaryotes

• Belong to the kingdoms Archaebacteria and Eubacteria

• Because they are so different, many scientists propose that archaebacteria and eubacteria arose from a common ancestor several billion years ago.

Archaebacteria: The extremists

• There are three types of archaebacteria that live mainly in extreme habitats where there is usually no free oxygen available.

– Methane gas producers• Lake sediments• Cow intestines• Sewage treatment plants

Archaebacteria: The extremists

– water with high concentrations of salt.

Dead Sea

Archaebacteria: The extremists

– hot, acidic waters of sulfur springs.

– These bacteria are chemautotrophic (make energy from chemicals)

Eubacteria: true bacteria• Some are autotrophic

– Photosynthetic

• Cyanobacteria

– Some are chemautotrophic

Eubacteria: true bacteria

• Some are heterotrophic = “eaters”– Decomposers: break down dead plants or

animals– Symbiotic: have close association with

another organism (parasitic or mutualistic)

Bacterial Cells

• Smallest single-celled organisms (2μm)

• Prokaryotic (lack a nucleus)

• Have a cell wall– Made of peptidoglycan (unique)– Cytoplasm is hypertonic, protects cell from

exploding– Antibiotics may disrupt cell wall

Bacteria on a pin

Bacterial Cells

• May be surrounded by a capsule– Sticky– Protects

• May have flagella

• May form endospore under harsh conditions– Withstands boiling, drying up– Cell emerges when conditions improve

Anthrax endospore

Bacterial Cells

• Different shapes– Coccoid = spherical– Baccilus = rod-shaped– Spirillus = spiral shaped

Bacterial Reproduction

• Binary fission (bacterial cell division)

Nitrogen Fixation

• Ability to convert nitrogen gas to ammonia that a plant can use

• Legumes (clover, beans, alfalfa) have these bacteria near roots– Rotated crop

Bacterial Importance

• Major Decomposers

• Can cause disease

• Can cure disease (many antibiotics come from bacteria)

• Can spoil food

• Can make food– Yogurt, cheese, vinegar, sauerkraut

Bacteria cause diseaseBacteria cause diseaseDiseases Caused by Bacteria

Disease Transmission Symptoms Treatment

Strep throat

(Streptococcus)

Inhale or ingest throughmouth

Fever, sore throat,swollen neck glands

Antibiotic

Tuberculosis Inhale Fatigue, fever, nightsweats, cough, weight loss, chest pain

Antibiotic

Tetanus Puncturewound

Stiff jaw, musclespasms, paralysis

Open and clean wound,antibiotic; give antitoxin

Lyme disease Bite ofinfected tick

Rash at site of bite,chills, body aches,joint swelling

Antibiotic

Dentalcavities (caries)

Bacteriain mouth

Destruction of toothenamel, toothache

Remove and fill thedestroyed area of tooth

Diptheria Inhale orclose contact

Sore throat, fever,heart or breathingfailure

Vaccination to prevent, antibiotics