Reproduction and Development

Summary

Summary
 
Key concepts


    (v) Six kingdom classification: Most recent classification is six kingdom classification proposed by three microbiologist – Carl woese, Kandler, Wheelis
    1. Six kingdom of Woese based on recent recent nucleic acid hybridization
      • DNA sequencing method
      • Comparing base sequence of 16S rRNA from variety of organism
    2. Woese, Kandler, Wheelis proposed bacteria should be divided into archaebacteria and eubacteria on the basis of 16S rRNA base sequence
    3. Domain: (i) Taxonomic categories above the rank of kingdom on the basis of 16S rRNA gene sequence called Domain
  • Topic – Moera
  • Topic – Moera
  • Topic – Protista
  • Topic – Fungi
  • Topic – Fungi
  • Topic – Plantae
  • Topic – Viruses, Viroids
  • Viruses and Viroids
  • 1. Viruses
    The term 'Virus' means poisonous fluid. The word was coined by Louis Pasteur. Viruses are very small (0.05 – 0.2 µm), infective, nucleoprotein particles, which can be called as living because of the presence of nucleic acid as genetic material and ability to produce their own copy – viruses. They show only some properties of living beings, otherwise they behave like non – livings. Hence, these are referred to as the connecting link between living and non – living.
    • On the basis of nature of genetic material, the viruses are of two types
    1. Adenovirus DNA containing, e.g., HIV, etc.
    2. Retrovirus RNA containing, e.g., Rous sarcoma virus, etc.
    On the basis of their host, the viruses can be categorised as
    1. Animal virus (Zoophagineae), e.g., HIV, sarcoma, etc.
    2. Plant virus (Phytophagineae), e.g., TMV, etc.
    3. Bacterial viruses (Phagineae), e.g., T4 phage, etc.
  • Topic – Introduction
    • S.No Characters Monera Protista Fungi Plantae Animalia
    1 Complexity of organisms Uni or Multicellular Unicellular Uni or Multicellular Multicellular Multicellular
    2 Type of cell Prokaryotic Eukaryotic Eukaryotic Eukaryotic Eukaryotic
    3 Cell wall Non cellulosic, has polysaccharides and amino acids. Present/absent Chitin (Fungal cellulose) Cellulose Absent
    4 Nucleus Incipient Distinct & well organised Distinct & well organised Distinct & well organised Distinct & well organised
    5 Nutrition Auto or heterotrophic Auto or heterotrophic Heterotrophic (absorptive) Autotrophic (Photosynthetic) Heterotrophic (ingestive)
    6 True tissue system Absent Absent Absent Present Present
    7 Motility Present/absent, 9 + 2 organisation is absent in flagella Present, Flagella show 9 + 2 arrangement. Present/absent, Flagella show 9 + 2 arrangement. Present/absent, Flagella show 9 + 2 arrangement. Present, Flagella show 9 + 2 arrangement.
    8 Reproduction Sexual reproduction absent Sexual reproduction takes place, Melosis is zygotic or gametic. Sexual reproduction takes place, Melosis is zygotic. Sexual reproduction takes place, Melosis is zygotic or sporic. Sexual reproduction takes place, Melosis is gametic.
    9 Ecological role Producers/decomposers. Producers/decomposers/consumers. Decomposers. Producers. Consumers.
  • Six Kingdom System:
    On the basis of gene sequences, six kingdom system proposed by Gray and Doolittle (1982).
  • Domain System:
    On the basis of genetic characters particularly genetic analysis of 16S rRNA, Carl woese proposed three domains system – Archaea, Bacteria and Eukarya.
  • Topic – Monera