G11 Life science

• Micro-organisms


  Organisms which are too small to be seen with the naked eye
• Kingdoms of Life

  • Monera (Bacteria)
  • Protista
  • Fungi
  • Plantae
  • Animalia
• Taxonomist


  A scientist who is responsible for the placing of an organism within a specific group
• Virus


  Displays some non-living as well as living characteristics
• Viruses

  • Consist of a core of either DNA or RNA enclosed by a protein coat called a capsid
  • Occur in a variety of shapes
  • Cannot respire, feed or excrete waste
  • Do not have a cytoplasm and do not have any membrane bound organelles
  • All viruses are obligate internal parasites
• Capsid

  A protein coat surrounding the nucleic material of a virus
• Acellular


  Non-cellular
• Obligate parasite


  A parasitic organism that cannot complete its life-cycle without exploiting a suitable host
• Host

  An organism that harbours a parasite
• Pathogenic

  An organism that causes disease
• Bacteriophage

  A type of virus that infects bacteria
• Nucleoid


  An irregularly shaped region within the cell of a prokaryote that contains all or most of the genetic material
• Prokaryotic


  An organism where the nuclear material is not enclosed in a membrane
• Eukaryotic


  Any single or multicellular group of organisms that have a membrane-bound nucleus containing genetic material
• Flagellum

  A whip-like, protruding filaments that help cells or micro-organisms move
• Autotrophic


  Organisms which can synthesize their own food
• Bacteria belong to the Kingdom Monera
• Bacteria are found everywhere on earth
• Some bacteria are pathogenic and cause diseases such as tuberculosis, while most are useful
• Micro-organisms play a role in maintaining a balance in the environment
• Roles of micro-organisms in the environment

  • In food chains
  • As decomposers
  • In the nitrogen cycle
• Micro-organisms can have symbiotic relationships
• Symbiotic relationships

  • Lichens
  • Nitrogen fixing bacteria and plants
  • E. coli and the human intestine
  • Mycorrhizal fungi and the roots of higher plants
• Diseases caused by micro-organisms

  • Diseases caused by viruses (Rabies, HIV/AIDS, Influenza)
  • Diseases caused by bacteria (Blight, Cholera, Tuberculosis, Anthrax)
  • Diseases caused by Protista (Malaria)
  • Diseases caused by fungi (Rusts, Thrush, Ringworm, Athlete's foot)
• Immune responses

  • The response of plants against an infecting micro-organism
  • The response of animals against an infecting micro-organism (Lymphocytes, Phagocytes)
  • Vaccinations
  • The use of drugs to fight infecting micro-organisms (Antibiotics)
• Biotechnology is used to make antibiotics and insulin
• Traditional technology is also used
• Viruses

  Obligate internal parasites that cannot multiply without infecting another living organism or host
• Organisms that viruses can infect

  • Bacteria
  • Protists
  • Plants
  • Animals
• Bacteriophages


  Viruses that infect bacteria
• Viruses cause diseases and are said to be pathogenic
• Diseases caused by viruses in humans

  • HIV/AIDS
  • Poliomyelitis
  • Chickenpox
  • Herpes
  • Influenza
• If a virus cannot find a host, they can become dormant
• Bacteria


  Belong to the Kingdom Monera, found everywhere on earth, some are pathogenic and cause diseases while most are useful
• Flagellum

  A whip-like, protruding filament that helps cells or micro-organisms move
• Autotrophic


  Organisms which can synthesize their own food e.g. green plants, algae and some bacteria
• Heterotrophic


  Any organism that sources food from its environment because it cannot make its own food, e.g. animals, fungi, most bacteria
• Saprophytic


  Plant or fungal microorganisms that feeds on dead or decaying tissues of other organisms
• Binary fission

  Asexual reproduction of a single cell in which divides by mitosis; the cell regenerates as two or more separate cells having the same chromosomal identities as the parent cell
• Endospore


  A tough, protective, non-reproductive bacteria structure that contains DNA and cytoplasm and lies dormant to survive unfavourable environmental conditions in order that it can germinate once conditions improve