Staining Techniques: Negative Staining Quiz

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Questions and Answers

What is the purpose of capsule staining in microbiology?

  • To detect the presence of capsules that protect bacteria (correct)
  • To visualize flagella on bacterial cells
  • To observe the gelatinous outer layer of bacterial cells
  • To identify the presence of spores in bacteria

Which stain is used to observe capsules in the capsule staining process?

  • Ziehl's Carbol Fuchsin
  • Congo Red (correct)
  • Methylene Blue
  • Crystal Violet

What does a clear halo around bacterial cells indicate in capsule staining?

  • Presence of capsules
  • Presence of spores
  • Absence of flagella
  • Absence of capsules (correct)

How does capsule staining contribute to a bacteriologist's understanding of bacterial morphology?

<p>By distinguishing encapsulated and non-encapsulated bacteria (B)</p> Signup and view all the answers

Which type of bacteria is likely to have a slimy or mucoid appearance due to the presence of capsules?

<p>Encapsulated bacteria (D)</p> Signup and view all the answers

What distinguishes capsule staining from flagella staining in microbiology?

<p>The observation of specific bacterial structures (B)</p> Signup and view all the answers

Why is heat fixation not recommended in the preparation of a bacterial smear for capsule staining?

<p>To avoid denaturing the gelatinous outer layer of cells (B)</p> Signup and view all the answers

What is the role of crystal violet stain in capsule staining?

<p>To stain bacterial cells but not the capsules (C)</p> Signup and view all the answers

How can capsule staining be useful in differentiating between pathogenic and non-pathogenic bacteria?

<p>By indicating the presence of capsules. (B)</p> Signup and view all the answers

Match the following components of culture media with their descriptions:

<p>Meat extract = Contains amino acids, vitamins, and mineral salts Yeast extract = Stimulates the growth of bacteria Peptones = Hydrolyzed animal/plant protein with nitrogen and amino acids Salts = Includes Mg, K, Fe, Ca for bacterial enzyme activity</p> Signup and view all the answers

Match the following thermal requirements with their temperature ranges:

<p>Psychrophilic = Grows below 10 degrees Celsius Mesophilic = Grows at 20-40 degrees Celsius Thermophilic = Grows at 50-55 degrees Celsius pH REQUIREMENTS = Match the following pH categories with their descriptions:</p> Signup and view all the answers

Match the following pH categories with their descriptions:

<p>Acidophiles = Thrive under highly acidic conditions Neutrophiles = Grow optimally at a pH between 5 and 8 Alkaliphiles/Basophiles = Grow optimally at pH values above 9</p> Signup and view all the answers

Match the physical state/consistency of culture media with their descriptions:

<p>Liquid (no solidifying agent) = Example: Broth Agarose = Inner polysaccharide of seaweed/marine algae used as a solidifying agent Water = Essential for bacterial growth and can be distilled water Thermal Requirements = Matching temperature ranges with bacterial growth</p> Signup and view all the answers

Match the following terms with their corresponding description:

<p>Semisolid media = Exhibits gelatinous consistency and contains 0.5 to 1% agar Enrichment media = Usually a broth that enhances the growth of an organism Selective media = Selects for the growth of a particular organism while inhibiting others through inhibitors Differential media = Provides distinct colonial appearance of microorganisms to aid in their identification</p> Signup and view all the answers

Match the following composition types with their definitions:

<p>Synthetic/Chemically-defined media = Exact composition is known and defined chemically Complex/Non-synthetic media = Contains at least one composition which is not chemically defined Tissue culture media = Used for organisms that cannot grow in cell-free media Selective-Differential media = Allows certain types of organisms to grow and differentiate while inhibiting others</p> Signup and view all the answers

Match the following cell lines with their corresponding species or origin:

<p>Mccoy cell = Mouse cell-like Vero cell = African green monkey A549 cell = Lung carcinoma Hela cell = Cervical carcinoma</p> Signup and view all the answers

Match the following physical forms of media distribution with their descriptions:

<p>Plated solid media = Dispensed in petri dishes as solid media Tubed media = Dispensed in test tubes, can be liquid or solid Liquid enrichment media = Usually a broth that enhances organism growth Solid selective-differential media = Allows certain organisms to grow and differentiate while inhibiting others</p> Signup and view all the answers

Match the following terms with their correct meaning:

<p>Vivo = Research done on a living organism Vitro = Research done in a laboratory dish or test tube Carbon = Required for cellular constituents Salt = An essential nutrient for microbial growth</p> Signup and view all the answers

Match the following microbial growth requirements with their correct functions:

<p>Nitrogen = Needed for proteins and nucleic acids Minerals = Provide essential nutrients for growth Growth Factors = Key compounds to support cell growth Water/Moisture = Essential for maintaining cellular hydration</p> Signup and view all the answers

Match the following bacterial characteristics with their correct staining technique:

<p>Peritrichous bacteria = Negative staining technique Monotrichous bacteria = Negative staining technique Ampitrichous bacteria = Negative staining technique Natasha Natividad = Negative staining technique</p> Signup and view all the answers

Match the following dyes with their suitable staining techniques:

<p>Toluidine blue O and malachite green = Basic dyes used in negative staining India Ink or Nigrosin = Acidic stain utilized in negative staining Crystal violet = Basic stain for capsule staining Safranin = Counterstain in Gram staining</p> Signup and view all the answers

Match the following bacterial species with their motility characteristics:

<p>B.cereus, S.typhi, E.coli, B.subtilis, Klebsiella = Peritrichous bacteria V.cholerae, Campylobacter spp. = Monotrichous bacteria C.jejuni, P.aeruginosa = Except Monotrichous bacteria C.jejuni, P.aeruginosa, Natasha Natividad = Ampitrichous bacteria</p> Signup and view all the answers

Match the following advantages with the corresponding staining technique:

<p>No need to heat fix, Some bacterial spp. are resistant to basic stains = Advantages of negative staining Gives easily visible unstained cells against black colored background, Simple and quick process = Advantages of negative staining Enhances contrast between different structures of bacterial cells = Advantages of Gram staining Allows differentiation between pathogenic and non-pathogenic bacteria based on cell wall composition = Advantages of Gram staining</p> Signup and view all the answers

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Study Notes

Staining Techniques

  • Negative staining: uses acidic stain (India Ink or Nigrosin) that releases a hydrogen ion, causing the dye's chromophore to become negatively charged, which is repelled by the negatively charged surface of most bacterial cells.
  • Advantages of negative staining: no need to heat fix, useful for bacterial spp. resistant to basic stains, and provides an easily visible unstained cell against a black background.

Flagella Staining

  • Ziehl's carbol fuchsin is commonly used for flagella staining.
  • Carbol fuchsin is a mixture of basic fuchsin and phenol, which has a great affinity towards the mycolic acids found in the cell membrane of bacteria.
  • It also contains tannic acid and potassium alum, which coat and thicken the flagellum to make it visible.

Metachromatic Staining

  • Albert stain is made up of toluidine blue O and malachite green, both of which are basic dyes.
  • Toluidine blue O stains volutin granules, while malachite green stains the cytoplasm blue-green.
  • Adding Albert's iodine causes the metachromatic property to be lost, and the granules appear blue-black in color.

Capsule Staining

  • Capsules are gelatinous outer layers composed of polysaccharides or polypeptides secreted by bacterial cells.
  • Capsules protect bacteria from phagocytosis and make colonies appear slimy or mucoid.
  • Capsule staining uses Congo red as the primary stain, followed by crystal violet as the counterstain.

Microbial Growth

  • Nutritional requirements: carbon, nitrogen, minerals, salt, growth factors, and water/moisture.
  • Vivo: research done on a living organism.
  • Vitro: research done in a laboratory dish or test tube.

Culture Media

  • Components: meat extract, yeast extract, peptones, salts, agarose, and water.
  • Thermal requirements: psychrophilic (below 10°C), mesophilic (20-40°C), and thermophilic (50-55°C).
  • pH requirements: acidophiles (highly acidic), neutrophiles (pH 5-8), and alkaliphiles/basophiles (pH above 9).

Classification of Culture Media

  • According to physical state/consistency: liquid, semisolid, and solid.
  • According to composition: synthetic/chemically defined, complex/non-synthetic, and selective.
  • According to dispensing/distribution: plated solid media, tubed media, and selective-differential.
  • According to function and use: supportive/general purpose, selective, and differential media.

Bacterial Morphology

  • Peritrichous bacteria: Bacillus cereus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Klebsiella.
  • Monotrichous bacteria: Vibrio cholerae, Campylobacter spp. (except C. jejuni).
  • Ampitrichous bacteria: C. jejuni.

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