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Structure and function of bacterial and fungal cells

BY

Dr.Jitender Kumar

Department of biotechnology

HMV,Jalandhar

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Introduction

  • Micro organism include both prokaryotic and eukaryotic organism
  • Cellular structures present in cell
  • Functional anatomy

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Structure of bacterial cell

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Gram positive and Gram negative bacteria

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General features of Gram positive bacteria

  • Thick cell wall
  • Violet color in Gram staining
  • Outer membrane
  • Bacillus, Clostridium

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General features of Gram negative bacteria

  • Thin cell wall
  • Pink color in Gram staining
  • Outer membrane present
  • E.Coli,Rhizobium etc.

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Structure of capsule

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Capsule and slime layer

  • Bacterial cells are surrounded by the extracellular polymeric substances (epsi) which is commonly called as capsule or glycocalyx
  • Presence of capsule is detected by negative staining such as India ink method.
  • Capsule is a gelatinous polymer made up of either polysaccharide or polypeptide or both polysaccharide may be homo/heteropolysaccharide.
  • It is sticky in nature secreted from inside the cell and firmly attached to the surface of the cell wall.

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Capsule and slime layer

  • Capsule is a gelatinous polymer made up of either polysaccharide or polypeptide or both polysaccharide may be homo/heteropolysaccharide.
  • It is sticky in nature secreted from inside the cell and firmly attached to the surface of the cell wall.

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Feature of bacteria

  • Bacteria Shapes Bacteria are commonly in three basic shapes Coccus (sphere) Bacillus (rod) Spirillium (spiral)
  • Cell Wall Characteristics Different types of bacteria have different types of cell walls Differences in cell wall composition can be studied using gram staining Depending on their cell wall, bacteria can be classified as Gram-Positive or Gram Negative

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Feature of bacteria

  • Gram Positive Bacteria These bacteria have a thick layer of peptidoglycan in their cell walls These bacteria retain dye-iodine complex in their cell walls and appear purple under the microscope
  • Gram Negative Bacteria These bacteria have a thin layer of peptidoglycan in their cell walls These bacteria do NOT retain the dye These bacteria appear pink under the microscope�

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Characters of bacterial components

  • Bacterial movement flagella long whip like structure that propels bacteria May have none, one or several.
  • Bacterial movement Pilli (cilia) short hair like appendages that adhere bacteria to different surfaces.
  • Bacterial movement slime some bacteria secrete slime like material they glide along.
  • No movement some bacteria do not show movement.�

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Characters of bacterial components

  •  Bacterial Reproduction In favorable conditions, bacteria can grow and reproduce as often as every 20 minutes
  • Methods of bacterial reproduction
  • Binary Fission
  • Conjugation
  • Spore Formation

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Structure of slime layer

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Flagella and fimbria

  • One flagella = Monotrichous
  • Cluster at one end = Lophotrichous

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  • Both ends = Amphitrichous

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  • Covering the cell = Peritrichous

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Characters of bacterial components

  • Not on all bacterial cells but if present it’s the outermost layer.
  • Capsule – tends to be thick, rigid and smooth.
  • Slime layer – is thinner & less rigid, globular extra layer guards against desiccation
  • Protects the cell from phagocytosis(S. pneumoniae)
  • Can be used as attachment such as in tooth decay bacteria (S. mutans)

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Flagella structure

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Bibliography

  • An introduction to microbiology by P.Tauro,K.K.Kapoor,K.S.Yadav ,New age international publishers
  • General microbiology by R.P.Singh ,Kalyani publishers.

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  • THANK YOU