Bacteria and Their Characteristics

Bacteria on Earth

• There is more bacteria on Earth than every other living organism combined.
• There are more individual bacterial cells in your mouth than mammals on Earth.

Bacterial Characteristics

• All bacteria are single-celled prokaryotes.
• Prokaryotes lack a nucleus and membrane-bound organelles like mitochondria and chloroplasts.

Kingdom Archaebacteria

• Thought to resemble the first life forms on Earth.
• Thrive in extreme environments.
• Classified by their habitats.

Methanogens

• Live in oxygen-poor environments.
• Produce methane (swamp gas).
• Found in the intestines of cows.

Thermoacidophiles

• Prefer high temperatures (60-250°C) and acidic conditions (pH 2-4).
• Found in hot springs like Yellowstone National Park.

Chemosynthesizers

• Use inorganic compounds to convert them to energy.
• Found near deep ocean vents.
• Convert H2S to energy.

Extreme Halophiles

• Live in extremely salty conditions.
• Tolerate salt concentrations up to 10 times higher than normal seawater.
• Found in the Dead Sea and Great Salt Lake.

Kingdom Eubacteria

• Differ from Archaebacteria in three ways:
  • Cell walls contain peptidoglycan.
  • Plasma membranes contain distinct lipids.
  • DNA structure is different.

Classifying Eubacteria

• Classified by various methods:
  • Shape: Rod-shaped (bacillus), circular (coccus), spiral-shaped (spirilla), comma (vibrio).
  • Cell Wall Composition: Determined by Gram staining (Gram-positive stain purple, Gram-negative stain red).
  • Motility: How and if they move (flagella – whiplike tail).
  • Colony Appearance: Groups of bacteria form colonies with distinct textures, shapes, and colors.
  • Respiration: Aerobic, anaerobic, facultative anaerobes, obligate aerobes, and obligate anaerobes.
  • Metabolism: Source of energy:
    • Autotrophs: Make their own food (photosynthetic).
    • Heterotrophs: Consume other organisms.
    • Chemotrophs: Consume inorganic compounds.

Bacterial Reproduction

• Occurs through various methods:
  • Binary Fission: Asexual reproduction producing identical cells. Chromosome replicates and the cell divides.
  • Conjugation: Exchange of genetic material between two bacteria through structures called pili.
  • Transformation: Living bacteria acquire DNA from dead bacterial cells.
  • Transduction: Viruses transport bacterial DNA from one cell to another.
  • Endospores: Some species develop these under unfavorable conditions. The spore dissolves and the bacteria reactivates when conditions improve.

Treating Bacterial Infections

• Typically treated with antibiotics.
• Antibiotics disrupt bacterial cell membranes or inhibit protein synthesis.
• Antibiotic resistance is a concern due to improper antibiotic usage.
• Some bacterial infections can be prevented through vaccines (e.g., Tetanus, Diphtheria, Whooping Cough).

Bacterial Infections Affecting Humans

- E. coli
- Strep Throat
- Salmonella
- Bacterial Meningitis
- TB (Tuberculosis)
- Gonorrhea
- Bacterial Pneumonia
- Diptheria
- Syphilis
- MRSA
- Whooping Cough
- Chlamydia
- Bubonic Plague 

Explore the fascinating world of bacteria, including their unique characteristics as prokaryotes and various types such as archaebacteria. Learn about specialized groups like methanogens, thermoacidophiles, and extreme halophiles, and their remarkable adaptations to extreme environments. Test your knowledge with this quiz!