Very basic bacterial structure and function

  • Ribosomes are the site of protein synthesis and are made up of rRNA and proteins.
  • The nucleoid contains the bacterial chromosome which is composed of DNA
  • The plasma membrane is the lipid bilayer that separates the inside of the cell from the outside and plays roles in signaling, transport and structure of the cells
  • Cell walls give bacteria their shape and provide protection. Made of a rigid bilayer of peptidoglycan and techoic acids.
  • Major components of the cell wall is peptidoglycan, also known as murein which is a large polymer with 3 components.
  • Gram +ve bacteria have large cell walls
  • Gram –ve bacteria only have 1 or 2 layers of peptidoglycan and no techoic acids, therefore not as complex as gram +ves
  • Gram –ve bacteria also have a LPS endotoxin with 3 components and a lipid A, which is highly toxic.
  • Capsule on bacteria surrounds cells and is made of polypeptides and polysaccharides, this can be seen be staining.
  • Glycocalyx is a slimy outter layer on bacteria that is involved in adhesion, clumping and biofilm formation in vivo.
  • Pili and fimbriae are finger like projections that are used by bacteria to adhere to other cells
  • Flagella are organs of motility that are expressed by motile bacterium
  • In poor growth conditions some bacteria such as clostridium produce spores, this enables them to survive for long periods of time and germinate again when growth conditions are favorable again.
  • Biofilms: bacteria may attach to cell surfaces and produce a slime, they then divide and produce microcolonies within the slime layer- constructing a biofilm full of nutrients and growth factors.



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