Bacterial Structure

  1. what are the general structures of bacteria
    • unicellular
    • no true nucleus, instead nucleoid region
    • small genomes with very little non-coding DNA
    • 70S ribosomes
    • many have plasmids
  2. what are plasmids
    • circular molecules of DNA that are much smaller than chromosomes
    • additional genes besides their core genomes
    • carries non essential genes that give the cell adaptive benefits (i.e antibiotic resistance genes, virulence genes)
    • bacteria can exchange plasmids by exposure to virulent bacteria
    • contains genes that allow them to replicate within the cell and transfer between cells
  3. describe the nucleoid region of bacteria
    • often contain one circular chromosome
    • no histones to organize chromosome
  4. how is parasitic bacterial genes different than free living bacteria
    • uses host cell's enzyme and nutrients
    • protected from environmental stresses by host
  5. how are bacterial genes organized and describe its f(x)
    • organized by their products
    • genes that code for enzymes in the same pathway tend to be on the same operon
    • all genes in an operon are turned off/on at the same time
  6. how do host signals (temperature, nutrients) affect virulence genes
    • host signals can turn virulence genes on
    • allows cells to infect hosts when conditions are right
  7. what is horizontal gene transfer
    • "lateral gene transfer"
    • occurs when bacteria are close to each other, conjugate, and share genetic information (plasmids).
    • results to antibiotic resistance and virulence genes that rapidly spread through bacterial communities
  8. can genes be shared among cells of the same species or between distantly related species
  9. what is transduction
    transfer of DNA from one bacteria to another
  10. what is conjugation
    transferring plasmid from one bacteria to another
  11. Describe the bacterial cell wall
    • composed of peptidoglycan (PG), which are short chains of amino acids that are cross links between sugar residues
    • the cell wall is outside of the cytplasmic membrane.
    • f(x): resists turgor pressure and determines cell shape
  12. what type of cell wall is this?
    Image Upload 1
    • gram negative
    • thin peptidoglycan cell wall
    • contains outer membrane
  13. what type of cell wall is this?
    Image Upload 2
    • gram positive
    • thick peptidoglycan cell wall
    • no outer membrane
  14. what is periplasm?
    • space between the the outer membrane and inner cytoplasmic membrane
    • contains transport, degradative, and cell wall synthetic proteins
  15. describe the bacterial cell membrane(s)
    • composed of phospholipid bilayer
    • contains; proteins, glycoproteins, lipoproteins, lipopolysaccharides
  16. where does bacterial respiration (aerobic and anaerobic) occur
    cytosolic membrane
  17. describe the surface proteins on the cell membrane
    • contains antigens that are detected by antibodies
    • adhesins that help cells stick to surfaces
    • metabolic enzymes that
  18. what are capsules
    • outer most layer of some bacteria, found in both gram (+) and gram (-)
    • made of polysaccharides
    • is an important virulence factor
  19. how are capsules important virulence factors
    • prevents recognition and engulfment by phagocytic cells
    • protect cells from dessication, bacteriophages, detergents
    • help cells adhere to surfaces, including host cells
  20. what are lipopolysaccharides (LPS)
    • an essential part of the outer membrane of gram (-) bacteria
    • an endotoxin and pathogen-associated molecular pattern (PAMP)
  21. how is LPS a pathogen associated molecular pattern (PAMP)
    • stimulates innate immune response
    • can induce fever and shock
  22. endotoxin activity is only found in what G +/- ?
    G (-)
  23. exotoxin activity is onlyfound in what G +/- ?
  24. what are the types of bacterial appendages
    • flagella
    • pili
  25. both flagella and pili are involved in the development of what
    bacterial biofilms
  26. describe flagella
    • very long "tail like structures tha move cells┬álike a rotating propeller
    • used primarily for bacterial motility
    • flagellin proteins can be PAMP
    • can extend and retract to move bacterial cells
  27. what is PAMP
    pathogen associated molecular pattern
  28. what is pili
    • "fimbria(e)"
    • used for motility, adherence, conjugation
    • often have adhesins at their ends to stick to host tissues. Attributes to virulence of pathogens
    • Pilin protein can be PAMP
  29. describe the difference between swimming and swarming
    • swimming: moving through liquid medium
    • swarming: moving through semi solid or agar plate
  30. cells that swarm tend to have higher antibiotic resistance (T/F)
  31. describe biofilms
    • communities of bacteria encased in a complex of molecular matrix
    • contains exopolysaccharides, proteins, DNA
    • help bacteria to stick to surfaces and resist envrionment stress (dessication, antibiotics, phagocytosis)
  32. what is the significance of biofilms on hospital equipment and host tissues
    • hospitals: lead to drug resistant bacteria, infecting patients
    • biofilm can form host tissues that make infections difficult to eradicate
  33. what are endospores
    • "spores"
    • dormant structures that form in actively growing bacterial cells in response to stress, to improve their chances of surviving that stress
  34. are endospores metabolically active?
    no, they can survive without a source of nutrients or water
  35. what are some sterilization techniques that endospores are resistant to
    • dessication
    • UV radiation
    • extreme temperature
    • high pressure
    • disinfectants
    • antibiotics
  36. antibiotics prevents fast/slow pathogens?
    fast pathogens
  37. what are some important bacteria that form spores
    • bacillus antracis
    • bacillus cereus
    • clostridium tetani
    • clostridum difivile
    • clostridium botulinum
Card Set
Bacterial Structure
organelles and structure of bacteria