Bacteria and Their Classification

Bacteria

• Bacteria are single-celled organisms that are prokaryotes.
• Prokaryotes lack a nucleus and membrane-bound organelles such as mitochondria and chloroplasts.
• Bacteria are classified into two kingdoms: Archaebacteria and Eubacteria.

Archaebacteria

• Archaebacteria are thought to resemble the first life forms on Earth.
• Methanogens live in low-oxygen environments, produce methane, and are found in cow intestines.
• Thermoacidophiles thrive in high temperatures (60-250°C) and acidic environments (pH 2-4), found in hot springs like Yellowstone National Park.
• Chemosynthesizers use inorganic compounds for energy, found near deep ocean vents, and convert H2S to energy.
• Extreme Halophiles live in extremely salty conditions, up to 10 times saltier than seawater, found in the Dead Sea and Great Salt Lake.

Eubacteria

• Differ from Archaebacteria in three ways:
  • Their cell walls contain peptidoglycan.
  • Their plasma membranes have different lipids.
  • Their DNA is different.

Classifications of Eubacteria

• Shape:
  • Rod-shaped (bacillus)
  • Circular (coccus)
  • Spiral-shaped (spirilla)
  • Comma (vibrio)
• Cell Wall Composition:
  • Gram Positive stains purple.
  • Gram Negative stains red.
• Motility:
  • Flagella (a whip-like tail) for movement.
• Colony Appearance:
  • Colonies form with various textures, shapes, and colors.
• Respiration:
  • Aerobic - Needs oxygen to survive.
  • Anaerobic - Doesn't need oxygen to survive, may be killed by oxygen.
  • Facultative Anaerobes - Can live with or without oxygen.
  • Obligate Aerobes and Obligate Anaerobes - Require specific oxygen levels to live.
• Metabolism:
  • Autotrophs - Make their own food (photosynthetic).
  • Heterotrophs - Consume other organisms.
  • Chemotrophs - Consume inorganic compounds.

Bacterial Reproduction

• Binary Fission: Asexual reproduction where one cell divides into two identical daughter cells.
• Conjugation: Sexual reproduction where two bacteria connect using pilli and exchange genetic material.
• Transformation: Living bacteria take up DNA from dead bacterial cells.
• Transduction: Viruses transport bacterial DNA from one cell to another.
• Endospores: Some bacteria produce these dormant forms to survive unfavorable conditions.

Treating Bacterial Infections

• Antibiotics: Drugs that target bacteria, often work by disrupting the cell membrane or inhibiting protein synthesis.
• Antibiotic Resistance: Bacteria can develop resistance to antibiotics, posing a public health concern.
• Vaccines: Help prevent certain bacterial infections, similar to viral vaccines.

Bacterial Infections Affecting Humans

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

Bacteria

• Bacteria are single-celled organisms that are prokaryotes.
• Prokaryotes lack a nucleus and membrane-bound organelles like mitochondria and chloroplasts.
• Bacteria are divided into two kingdoms: Archaebacteria and Eubacteria.
• Archaebacteria are thought to resemble the first life forms on Earth and are adapted to extreme environments.
• Archaebacteria are further classified by their habitat:
  • Methanogens: Produce methane and live in oxygen-poor environments, like cow intestines.
  • Thermoacidophiles: Thrive in high temperatures (60-250°C) and acidic conditions (pH 2-4), such as hot springs.
  • Chemosynthesizers: Utilize inorganic compounds for energy, found near deep ocean vents, and convert H2S to energy.
  • Extreme Halophiles: Survive in highly salty environments, up to 10 times saltier than seawater (Dead Sea, Great Salt Lake).

Eubacteria

• Eubacteria differ from Archaebacteria in three ways:
  • Their cell walls contain peptidoglycan.
  • Their plasma membranes contain different lipids.
  • Their DNA is different.
• Eubacteria are classified by various methods:
  • Shape: Rod-shaped (bacillus), circular (coccus), spiral-shaped (spirilla), and comma (vibrio).
  • Cell Wall Composition: Determined by Gram staining, resulting in Gram-positive (stain purple) or Gram-negative (stain red) bacteria.
  • Motility: How and if they move, using flagella as a whiplike tail.
  • Colony Appearance: Groups of bacteria form colonies with varying textures, shapes, and colors.
  • Respiration:
    • Aerobic: Require oxygen.
    • Anaerobic: Do not require oxygen.
    • Facultative Anaerobes: Can live with or without oxygen.
    • Obligate Aerobes: Require oxygen.
    • Obligate Anaerobes: Cannot survive in the presence of oxygen.
  • Metabolism:
    • Autotrophs: Produce their own food through photosynthesis.
    • Heterotrophs: Consume other organisms.
    • Chemotrophs: Consume inorganic compounds.

Bacterial Reproduction

• Bacteria reproduce through several methods:
  • Binary Fission: Asexual reproduction producing identical cells. The chromosome replicates, and the cell divides. Most bacteria can double every 20 minutes.
  • Conjugation: Exchange of genetic material between two cells. This is a form of sexual reproduction, where bacteria connect using structures called pili for DNA exchange.
  • Transformation: Living bacteria absorb DNA from dead bacterial cells.
  • Transduction: Viruses transport bacterial DNA from one cell to another.
  • Endospores: Some bacteria form these under unfavorable conditions. The spore dissolves and the bacterial cell reactivates when conditions improve.

Treating Bacterial Infections

• Bacterial infections are often treated with antibiotics.
• Antibiotics work by disrupting the bacterial cell membrane or inhibiting protein synthesis.
• Antibiotic resistance is a growing concern due to improper antibiotic use, leading to bacteria developing immunity to treatments.
• Some bacterial infections can be prevented by vaccines like those for tetanus, diphtheria, and whooping cough.

Common Bacterial Infections

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