Which type of nutrition and reproduction is found in kingdom Monera?

Solution:

NUTRITION IN MONERA

Bacteria exhibit diverse nutritional strategies:

1. AUTOTROPHIC NUTRITION
2. Photosynthetic Autotrophs (Photoautotrophs):

• Mechanism: Use light energy to synthesize organic compounds
• Pigments: Bacteriochlorophyll (different from plant chlorophyll)
• Types:
  • Oxygenic: Cyanobacteria (release O₂)
  • Anoxygenic: Purple and green sulfur bacteria (use H₂S, not H₂O)
• Examples: Anabaena, Nostoc, Chromatium

1. Chemosynthetic Autotrophs (Chemoautotrophs):

• Mechanism: Oxidize inorganic chemicals for energy (ATP production)
• Substrates:

Bacterial Type	Oxidation Reaction	Example
Nitrifying	NH₃ → NO₂⁻ → NO₃⁻	Nitrosomonas, Nitrobacter
Sulfur	H₂S → S → SO₄²⁻	Thiobacillus
Iron	Fe²⁺ → Fe³⁺	Ferrobacillus
Hydrogen	H₂ → H₂O	Hydrogenomonas

1. HETEROTROPHIC NUTRITION
2. Saprophytic/Saprotrophic:

• Feed on dead organic matter
• Major decomposers in ecosystems
• Examples: Most soil bacteria

1. Symbiotic:

• Mutualistic: Rhizobium (nitrogen fixation in legumes)
• Commensalistic: coli (human gut)

1. Parasitic:

• Cause diseases in hosts
• Examples: Mycobacterium tuberculosis, Salmonella typhi

REPRODUCTION IN MONERA

1. ASEXUAL REPRODUCTION (Primary Mode)
2. Binary Fission:

• Most common method
• Process:
  1. DNA replication
  2. Cell elongation
  3. Septum formation
  4. Cell division into two identical daughter cells
• Time: Can occur every 20 minutes under optimal conditions
• Result: Clonal population

1. Spore Formation:

• Endospore Production:
  • Occurs under unfavourable conditions (heat, drought, nutrient depletion)
  • Highly resistant dormant structures
  • Examples: Bacillus, Clostridium
  • Characteristics:
    • Thick spore coat (peptidoglycan + proteins)
    • Can survive extreme temperatures (120°C), radiation, desiccation
    • Germinate when conditions improve

1. Budding:

• Rare in bacteria
• Small outgrowth develops into new individual
• Example: Hyphomicrobium

1. Fragmentation:

• Filamentous bacteria break into fragments
• Each fragment grows into new organism
• Example: Cyanobacteria like Oscillatoria

1. SEXUAL REPRODUCTION (Genetic Recombination)

Note: Bacteria do NOT undergo true sexual reproduction (no gamete formation/fusion). Instead, they exhibit parasexual processes:

1. Conjugation:

• Mechanism: Direct transfer of DNA through pilus
• Process:
  • Donor (F⁺) cell extends sex pilus
  • Connects to recipient (F⁻) cell
  • Plasmid DNA (often F-plasmid) transfers
• Significance: Horizontal gene transfer, antibiotic resistance spread

1. Transformation:

• Mechanism: Uptake of naked DNA from environment
• Discovery: Griffith's experiment (1928) with Streptococcus pneumoniae
• Applications: Genetic engineering

1. Transduction:

• Mechanism: DNA transfer via bacteriophage (virus)
• Types:
  • Generalized: Random bacterial DNA packaged
  • Specialized: Specific bacterial genes adjacent to prophage

Common Exam Pitfall: Remember that bacterial "sexual" reproduction lacks fertilization and meiosis—essential features of eukaryotic sexual reproduction.

Pro Tip: The vast majority of bacteria in nature are heterotrophic, with autotrophs representing specialized adaptations to specific environments.