introduction

• prokaryotic cell walls are made of peptidoglycans
• nucleiod

  single double stranded dna of bacteria is in here
• plasmids

  independant replication entities that carry genes that might offer a selective advantage
• injested spores germinate to bacteria
• endospores are formed within a normal vegetative cell in response to environmental stress, they are not reproductive
• gram positive cell wall consists of a thick, highly cross linked thick layer of peptidoglycan, and is strengthened by teichoic and lipoteichoic acid
• gram negative cell wall has a thinner peptidoglycan layer annd is surrounded by an outer membrane
• lipid A can act as a potent endotoxin during infection by gram negative bacteria
• lipopolysaccharides are used to identify bacteria
• gram postitive

  no outer membrane, usually contains lycine, has teichoic acid, but no lipoproteins or lipopolysaccharides
• gram negatve

  outer membrane, usually contains diaminopimelic acid, has no teichoic acid, but has lipoproteins and lipopolysaccharides
• capsules

  allow bacteria to attach to surfaces, and escape host defenses as they are poorly antigenic and anti-phagocytic
• fibrae

  hairlike appendages that are involved in attachment to surfaces
• aerobes


  grow in presence of oxygen
• anaerobes

  can grow in the absence of oxygen
• facultative anaerobes

  grow in presence and absence of oxygen
• microaerophilic

  require low concentrations of oxygen
• beta haemolytic

  completes lyses of red blood cells
• alpha haemolytic

  haemoglobin is oxidised
• gamma haemolytic

  no lysis
• macconkey agar

  selects for gram negative organisms to grow, and turns lactose fermenting bacteria red
• mannitol salt agar

  used to select for gram positive staph species, and highlights ones that are able to use mannitol
• catalase test

  differentiates gram postive cocci
• coagulase test

  differentiates s aureus from staph epidermis
• oxidase test

  tests different gram negative bacteria