L14 - Gram-stain-negative Bacteria

    Cards (81)

    • Who invented the Gram stain?
      Hans Christian Gram
    • What does the Gram stain divide Bacteria into?
      Gram-stain-positive and Gram-stain-negative
    • What is the color of the crystal violet stain?
      Blue-violet
    • What role does triiodide (I3-) play in the Gram stain?
      It helps trap the stain inside cells
    • What happens to cells after washing with ethanol in the Gram stain process?
      Some cells retain the violet dye, some do not
    • What are the two counterstains used in the Gram stain process?
      Bismarck brown and safranin O
    • What color do Gram-stain-positive cells appear after counterstaining?
      They still look violet
    • What color do Gram-stain-negative cells appear after counterstaining?
      Pink or brown
    • Why do Gram-stain-positive and Gram-stain-negative cells stain differently?
      It relates to the structure of their cell wall
    • What is the outer membrane of Gram-stain-negative bacteria composed of?
      A phospholipid bilayer with channel proteins
    • What is contained within the periplasm of Gram-stain-negative bacteria?
      Peptidoglycan (murein)
    • What anchors peptidoglycan to the outer membrane in Gram-stain-negative bacteria?
      Proteolipids
    • What are the repeating units in peptidoglycan?
      N-acetylmuramic acid and N-acetylglucosamine
    • What is the function of teichoic acids in Gram-stain-positive bacteria?
      They are part of the peptidoglycan layer
    • What is the structure of teichoic acids?
      Backbones of repeating sugar alcohols with phosphate groups
    • What is the taxonomic hierarchy used for Bacteria and Archaea?
      • Domain
      • Kingdom
      • Phylum
      • Class
      • Order
      • Family
      • Genus
      • Species
      • Subspecies
    • What is the strain code for Escherichia coli?
      K12 MG1655
    • What defines a species in Bacteria and Archaea?
      Whole-genome studies and single gene analysis
    • What is the type strain of a species?
      The strain designated when the species is named
    • What is the significance of the nomenclatural Code for Bacteria and Archaea?
      It is stricter than those for Zoology and Botany
    • What is the primary method of reproduction in Escherichia coli?
      Binary fission
    • Where is Escherichia coli commonly found?
      In the colon of most Mammalia
    • Why is Escherichia coli widely used in genetics and molecular biology?
      It grows fast and is easy to handle
    • What toxin does E. coli O157:H7 produce?
      Shiga toxin
    • What is the effect of shiga toxin produced by E. coli O157:H7?
      Causes bloody diarrhoea and kidney failure
    • What beneficial role do gut strains of E. coli play in humans?
      They produce vitamin K2
    • How do E. coli cells divide?
      They elongate, duplicate DNA, and form a septum
    • How often can some E. coli strains divide in complex media?
      Every 20 minutes
    • What types of respiration can E. coli perform?
      Respire O2 or nitrate, or ferment
    • What do E. coli ferment in the absence of O2 or NO3-?
      Sugars by mixed acid fermentation
    • What is Acidithiobacillus thiooxidans classified as?
      Obligate chemolithoautotroph
    • What is the pH range in which Acidithiobacillus thiooxidans can grow?
      pH 0.5 to 6.0
    • What is the significance of Acidithiobacillus thiooxidans in biohydrometallurgy?
      It extracts metals from low-grade ores
    • What is the chemical equation for the leaching of Cu2S?
      Cu2S + O2 + H2O → H2SO4 + 2Cu+ + 2H+
    • What is Desulfovibrio vulgaris classified as?
      Gram-stain-negative rods
    • Where is Desulfovibrio vulgaris commonly found?
      In water-logged soils and river sediments
    • What type of respiration does Desulfovibrio vulgaris perform?
      Obligate anaerobic respiration
    • How does Desulfovibrio vulgaris move?
      By single flagella at one pole
    • What are the characteristics of Acidithiobacillus thiooxidans?
      • Gram-stain-negative rods
      • Dividing by binary fission
      • Motile by single flagella
      • Extreme acidophile (pH 0.5 to 6.0)
      • Obligate chemolithoautotroph
    • What are the characteristics of Desulfovibrio vulgaris?
      • Gram-stain-negative rods
      • Dividing by binary fission
      • Motile by single flagella
      • Ubiquitous in water-logged soils
      • Obligate anaerobe