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Microbiology: Bacteria and Archaea

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Termini in questo insieme (26)

  • How do bacteria differ from eukaryotes in DNA packaging?
    Bacteria lack a nucleus and histones; their DNA is located in a nucleoid region.
  • What is unique about the bacterial cell wall composition?
    Bacterial cell walls contain peptidoglycan, a carbohydrate-protein complex unique to bacteria.
  • Name the essential components found in all bacterial cells.
    Cytoplasmic membrane, cytoplasm, ribosomes, cytoskeleton, and one or a few chromosomes.
  • What is the function of the bacterial glycocalyx?
    It is a carbohydrate coating that helps bacteria adhere to surfaces and can protect against desiccation.
  • Describe the shape and example of a coccus bacterium.
    Spherical or ball-shaped; example: Staphylococcus aureus.
  • What is a bacillus bacterium and its variations?
    Rod-shaped bacteria; can be blocky, spindle-shaped, round-ended, filamentous, or club-shaped.
  • Define vibrio bacteria with an example.
    Single, gently curved rods; example: Vibrio vulnificus.
  • What distinguishes spirillum from spirochete bacteria?
    Spirillum are rigid helices; spirochetes are more flexible, spring-like spirals.
  • List common arrangements of cocci bacteria.
    Single, diplococci (pairs), tetrads (groups of four), staphylococci (clusters), streptococci (chains), sarcina (cubical packets).
  • What are the main functions of bacterial flagella?
    Motility; composed of filament, hook, and basal body.
  • What role do fimbriae play in bacteria?
    Allow tight adhesion to epithelial cells, aiding colonization and infection.
  • What is the function of pili in bacteria?
    Used for conjugation, facilitating genetic exchange between bacterial cells.
  • Describe the bacterial S-layer.
    A single layer of proteins produced in hostile environments, forming a protective chain-link fence.
  • What is the difference between a slime layer and a capsule in the glycocalyx?
    Slime layer is loose and protects against water/nutrient loss; capsule is dense, sticky, and tightly bound.
  • How does the bacterial cell wall contribute to cell shape and protection?
    It provides strong structural support and determines shape; composed mainly of peptidoglycan.
  • What distinguishes Gram-positive from Gram-negative bacterial cell walls?

    Gram-positive have thick peptidoglycan layers with teichoic acids (acidic charge); Gram-negative have thin peptidoglycan and an outer membrane.

  • What is the role of the cytoplasmic membrane in bacteria?
    A lipid bilayer that regulates nutrient and waste transport; selectively permeable.
  • Why is the outer membrane important in Gram-negative bacteria?

    It provides an extra barrier, making them more resistant to antimicrobial chemicals and more difficult to kill than gram-positive bacteria

  • What are bacterial plasmids and their significance?
    Nonessential DNA pieces in the cytoplasm that confer traits like drug resistance and toxin production.
  • What are bacterial endospores and why are they important?
    Dormant, resistant structures formed by some bacteria to survive extreme conditions; very hard to kill.

  • What are the different arrangements of bacilli bacterium?

    single; diplobacilli (pairs of cells); streptobacilli (chains of cells); palisades (cells of a chain that are partially attached by a small hinge region)

  • Describe the capsule (specialized glycocalyx)

    formed by pathogenic bacteria; strong disease-causing ability; protects cells against host white blood cells (phagocytes); forms biofilms

  • What is the order of the bacterial cell envelope from in to out?

    cytoplasmic membrane, cell wall, outer membrane (then S layer, glycocalyx)

  • What does mycolic acid in bacterial cell walls do?

    Causes the bacteria to be more pathogenic.

  • What dissolves lipids?

    Alcohol-based compounds

  • What is sporulation?

    The process of forming endospores induced by environmental conditions.