2

• nucleoid region


  irregularly shaped, contains the bacterial chromosome, circle DS DNA
• size of bacterial genome

  130kb - 14 Mb
• fluoroquidone antibiotics 


  inhibit DNA gyrase enzyme to stop DNA coiling for packaging
• Plasmids


  additional to chromosome DNA , extra small and circular ds DNA pieces in cytoplasm.
• what do plasmids carry genes for

  not essential but may be useful for advantage - antibiotic resistance, virulence genes
• insertion sequence


  small fragment of DNA, carry genes for encoding enzymes for transposition of DNA
• Transposition


  moving of DNA between DNA/plasmid segments
• transposon 


  larger DNA fragment carry structural genetic info flanked by insertion sequences
• integron

  genetic element with ability to capture genes (usually in structural segment of transposon)
• promotor sequence 


  promotes transcription of genes into integral
• bacteria selection pressures (make them replicate fast)


  host immunity, antibiotics selecting for resistance, other organisms in microbiome
• 2 mechanisms of genetic variation

  horizontal gene transfer and vertical inheritance of random mutations
• bacili 


  rod shaped bacteria
• vertical inheritance of mutations in bacteria

  low frequency but rapidly replicating so have lots
• types of DNA mutations in bacteria (vertical)

  point mutations (single nt) and DNA rearrangements (insertion, inversion, deletion)
• mutation outmodes (vertical inheritance)

  deleterious - die out, beneficial - advantage for function so selective, neutral or silent - no effect on phenotype
• mechanisms of horizontal gene transfer in bacteria

  bacterial transformation, transduction, conjugation
• bacterial transformation


  donor bacteria dies, release DNA into environments and other bacteria pick up floating DNA, then recombined into recipient cell chromosome
• some bacteria is programmed to kill cells and then waits to pick up their released DNA
• bacterial conjugation


  sex pills move between cells and exchange genetic material, move across through the plasma (DNA comes from transposon)
• bacterial transduction


  bacteriophage virus infected bacterial cell, lands and injects NA into cell which replicates in bacterium. Then released and goes on a infect another cell but has picked up some of DNA from last cell by accident
• obligate aerobe - aerobic bacteria

  require oxygen
• facultative anaerobe 


  don't require oxygen but grow better in its presence
• aerotolerant anaerobe


  grow equally well in oxygen or without
• obligate anaerobe 


  killed by oxygen
• gram positive cocci - chains and pairs


  streptococcus and enterococcus
• gram positive cocci - clusters


  staphylococcus
• mycobacterium TB staining 


  doesn't stain well with gram stain due to waxy coat, use acid fast stain instead