Kingdom Classification - Monera

Kingdom Classification - Monera

Characteristics

• Unicellular: Organisms in this kingdom are single-celled.
• Prokaryotic: They lack a true nucleus and other membrane-bound organelles.
• Cell Wall: Most have a cell wall, but it is not made of cellulose.
• Nutrition: Can be autotrophic (photosynthetic or chemosynthetic) or heterotrophic.
• Reproduction: Primarily by binary fission.

Bacterial Cell Structure

Bacterial cells have a simple but robust structure that enables them to thrive in diverse environments.

• External Structures:
  • Capsule/Glycocalyx: An outer layer that protects the cell from dehydration and phagocytosis.
  • Flagella: Long, whip-like appendages for motility.
  • Pili and Fimbriae: Hair-like appendages for attachment and conjugation.
• Cell Envelope:
  • Cell Wall: Provides structural support and protection. Composed of peptidoglycan.
  • Plasma Membrane: A phospholipid bilayer that regulates the passage of substances.
• Internal Structures:
  • Cytoplasm: The gel-like substance that fills the cell.
  • Nucleoid: The region containing the bacterium's genetic material (a single, circular chromosome).
  • Ribosomes: Responsible for protein synthesis.
  • Plasmids: Small, circular, extrachromosomal DNA molecules that often carry genes for antibiotic resistance.

[Diagram of a Bacterial Cell]

Archaebacteria vs. Eubacteria

The Kingdom Monera is divided into two sub-kingdoms: Archaebacteria and Eubacteria.

• Archaebacteria:
  • These are ancient bacteria that live in extreme environments.
  • Their cell walls lack peptidoglycan.
  • Examples: Methanogens (produce methane), Halophiles (live in salty environments), Thermoacidophiles (live in hot, acidic environments).
• Eubacteria:
  • These are "true" bacteria.
  • Their cell walls are made of peptidoglycan.
  • Examples: Cyanobacteria (blue-green algae), Lactobacillus, E. coli.

Bacteria

• Shape: Bacteria can have various shapes:
  • Cocci: Spherical (e.g., Streptococcus)
  • Bacilli: Rod-shaped (e.g., Lactobacillus)
  • Spirilla: Spiral-shaped (e.g., Spirillum)
  • Vibrio: Comma-shaped (e.g., Vibrio cholerae)

Useful Bacteria (Applications related to daily life)

• Food Production: Used in making yogurt, cheese, buttermilk, and vinegar.
• Medicine: Used to produce antibiotics (e.g., Streptomycin) and vaccines.
• Agriculture: Nitrogen-fixing bacteria (e.g., Rhizobium) convert atmospheric nitrogen into a usable form for plants, enriching soil fertility.
• Decomposition: Decomposers break down dead organic matter, recycling nutrients in the ecosystem.
• Bioremediation: Used to clean up oil spills and other pollutants.

Harmful Bacteria (Applications related to daily life)

• Diseases: Cause various diseases in humans (e.g., Cholera, Tuberculosis, Typhoid), animals, and plants.
• Food Spoilage: Cause food to rot and become unfit for consumption.
• Denitrification: Some bacteria convert nitrates back into atmospheric nitrogen, reducing soil fertility.