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Flashcards in Bacteriology- overview Deck (11):

Understand and differentiate the morphology of common bacteria: Cocci, bacilli, spirochete

Cocci: round


Bacilli: rod-shaped


Spirochete: corkscrew


Know the difference between a prokaryotic and eukaryotic cell


  • no membrane bound organelles
  • no nuclear membrane
  • dna- single (often round plasmid)
  • replicate by binary fission


  • membrane bound organelles
  • nuclear membrane and nucleolus
  • dna-chromisome
  • replicate by mitosis


Bacterial cell structure: name and describe elements of...

  • Appendages (2)
  • Cell envelope (3)
  • Cytoplasmic content (2)


Bacterial Cell Structure

Appendages (not present in all bacteria)

  • Flagella-long and flowy and present in motile bact.
  • Pili (fimbriae)- short and hair-like and help cell adhere to stuff

Cell envelope= entire outer part of cell

  • capsule-outer most layer of cell. protects cell. polysaccharide
  • cell wall-middle outer layer.  rigidity
  • plasma membrane- inner outer layer. permeability barrier

Cytoplasmic content

  • chromisomes- genetic material of cell in nucleoid
  • ribosomes- protein synthesis


Describe differences in cell wall structure between gram positive and negative bacteria

Gram-positive cell wall

  • layer 1: capsule
  • layer 2: thick layer of peptidogylcan (murein)
  • layer 3. plasma membrane
  • techoic acids: run perpendicular to petidoglycan sheets

Gram-negative cell wall

  • layer 1: capsule
  • layer 2: phospholipid-lipopolysaccharide outer membrane
  • layer 3: thin peptidoglycan sheet
  • layer 4: plasma membrane

***the space between outer membrane and plasma membrane where peptidoglycan layer is is called periplasm.


Know details about LPS

  • location
  • structure
  • function

LPS = endotoxin = Lipopolysaccharide

Location- outer membrane of gram-negative cell wall

Structure- lipid head (inside membrane) with polysaccharide tail (outside cell)

  • Lipid A- toxic portion of molecule. causes fever, hemmorage and shock. 
  • polysaccharide- responsible for antigenic properties (how immune system will respond)

** O-specific polysaccharide may be part that provides adherence


Discuss bacterial chromosomes

Bacterial Chromisomes

  • haploid circular chromosome of DNA (nucleoid)
  • small extrachromosomal pieces of DNA= plasmids
  • chromisome is genetic control center of cell




Endospore= dormant form of a bacteria. 

Structure (outer to inner)

  • Exosporium
  • Spore coat
  • Cortex
  • Core wall-dipicolinic acid
  • INSIDE- ribosomes and chromisome


  • dormant form that bacteria can take on when conditions are not correct
  • allows some bacteria to stay dormant for years before regermination
  • the dehydrated core contains chromosome and ribosomes


Capsule function

Capsule function

  • adherence
  • resistance to phagocytic cells
  • antibody and drug resistance
  • reserve of nutrients
  • protection against drying



How would you technically determine gram+ or gram-? 

evaluate the components of the cell wall. 

Gram +

  • Thick wall
  • 1 layer
  • lots of peptid
  • techoic acids
  • NO LPS
  • sensative to penicillin
  • sensative to lysozyme

Gram -

  • Thin wall
  • 2 layers
  • less peptid
  • NO techoic acids
  • LPS
  • not sensative to penicillin
  • not sensative to lysozyme


Cell wall function

Cell wall function

  • prevents damage to PROTOPLAST
  • contains receptor sites for drugs and ligands for adherence
  • components responsible for symptoms
  • provides immonological distinction among strains of bact. 
  • lends rigitity and structure to cell
  • contains MUREIN (distinctive of bacteria)


Draw disease triad