Eubacteria
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Eubacteria

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IB Biology Option F SL

IB Biology Option F SL

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Eubacteria Eubacteria Presentation Transcript

  • Eubacteria
    IB Biology
  • Shapes of Eubacteria
    Yourtasks
    Copythediagramshowingthedifferentshapes of Eubacteria
    Identifytheshape of the bacteria in thepicturesbelow
    Drawhowyouwouldexpectthe bacteria to look fromthegivennames of the bacteria below.
    Label my shape!
    Draw me!
    Streptoccocusbovis
    Staphylococcusaureus
    Didyouknow!
    Bacterria can alter theirshape as a result of ageingorenvironmental shock!
    Thisisknown as pleomorphy.
    a) b) c)
  • Positions of flagellum
    Polar attachment
    Flagellumattached at oneorbothends
    Peritrichiousattachment
    Flagelladispersedrandomlyoverthesurface of thebacterium
    Task:
    Make a note of the different types of flagellum attachment
    Use your knowledge to identify the type of flagellum attachment in the pictures to the left
    View slide
  • Presence of fimbrae
    Task:
    Use thewords in thewordbankbelowtocopyouttheparagraph and fill in theblanks!
    __________ are short and rigid bristle-like projections that are anchored in the bacterial __________ membrane. They stretch out past the bacterial cell __________Fimbriae act as __________(marker molecules) and can also interact with the __________ cell membrane.
    In__________ (disease-causing) bacteria, the presence of a large number of fimbriae may help to prevent __________by the host cells.
    WORD BANK
    wall
    fimbriae
    phagocytosis
    plasma
    antigens
    pathogenic
    host
    View slide
  • Endospores
    Task:
    Writeoutthesentencesbelow in thecorrectorderto describe endosporeformation.
    When the environmental conditions are suitable, the endospore absorbs water, swells and the wall splits, releasing the cell inside.
    During this process, a portion of the cytoplasm and a copy of the bacterial chromosome undergo dehydration
    The resulting structure, called endospore can tolerate extreme environmental conditions and can remain viable for several years.
    The dehydrated organelles then get surrounded by a three-layered covering.
    It develops a new cell wall and starts functioning as a typical bacterial cell again.
    In certain bacteria like Clostridium and Bacillus, the cells tide over unfavourable conditions by forming endospores.
    Finally, the remaining part of cytoplasm and cell wall degenerate.
  • Bacterial Capsule
    Function
    • considered a virulence factor
    • enhances the ability of bacteria to cause disease (i.e. prevents phagocytosis)
    • capsule is slippery and fragile, so when a phagocyte tries to phagocytose the bacteria, it can slip away
    • capsules also contain water which protects bacteria against dessication
    • exclude bacterial viruses and most toxic materials such as detergents
    • capsules also help cells adhere to surfaces.
    Tasks:
    Make notes onthevariousaspects of bacterial capsules
    Usethedictionarytofinddefintionsforthewords in red
    Composition
    • usually composed of polysaccharides
    • water soluble
    Location and size
    very large structure
    lies outside the bacterial cell wall
    not easily washed off
    the cause of various diseases
  • Vibriofischeri
    Tasks
    Readthearticletakenfrom a scientific magazine below.
    Answerthequestionsbasedonthearticle in FULL, MEANINGFUL sentences
      The marine bacterium V. fischeri exists naturally either in a free-living planktonic state or as a symbiont of certain luminescent fish or squid (Ruby & Nealson, 1976, Ruby & McFall-Ngai, 1999). The bacteria colonisespecialised light organs in the fish or squid, which cause them to bioluminesce.
    Luminescence in the fish or squid is thought to be involved in the attraction of prey or even as camouflage. During the nocturnal feeding of the squid Euprymnascolopes, luminescence from the light organ is directed towards the sea floor and is modulated by the squid to match the intensity of moonlight, therefore preventing a shadow of the squid on the sea floor (Visick & McFall-Ngai, 2000).
    The source of the luminescence is the bacteria themselves. In the marine environment, the bacteria only luminesce when colonising the light organs and do not emit light when in the free-living state. It makes good evolutionary sense for the bacteria to tightly regulate bioluminescence as the mechanism by which light is produced is very energy intensive. Research carried out to answer the question of how V. fischeri regulates bioluminescence led to the discovery of bacterial quorum sensing.
    In which habitat is V. fischerinormally found?
    The bacterium is described as a ‘symbiont’. What does that mean?
    Which parts of the squid do V. fischericolonise?
    Define ‘bioluminescence’
    How does the squid use bioluminescence in order to escape predators?
    Why does V. fischeritightly regulate bioluminescence?
  • Quorum Sensing
    Tasks:
    Copythediagramtotheright
    Annotateyourdiagramwiththeadditional notes below
    Bioluminescence
    Quorum sensing the regulation of a bacterial process that depends on the density of the bacterial population
    Bacteria produce signalling molecules known as autoinducers
    These signalling molecules are detected by special receptors in the bacterial cell membrane
    When the bacterial population is low then the diffusion of autoinducer into the surroundings is almost zero
    As the population size increases the concentration of autoinducer reaches a threshold causing gene expression
    The genes are expressed because the binding of the autoinducer to the receptor causes the bacteria to start making moreautoinducer and other specific enzymes
  • Biofilms
    Watch the video on ‘Understanding Biofilms’
    Task:
    Make notes thatexplain
    -what a biofilmis
    -how a biofilmforms
    -whatdoes a biofilm look like
    Handy Hint!
    Youwon´tneedtowatchthewhole video
    You CAN rewind and fast forward it!