Chapter 4 – Microbiology Questions And Answers – Flashcards
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| Differences in Prokaryotes and Eukaryotes |
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| way DNA is packaged; composition of cell wall; no membrane bound organelles |
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| Flagella |
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| counterclockwise motion propels bacteria forward; clockwise motion causes bacteria to stop and tumble |
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| Parts of a a Flagella |
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| filament, hook, rod, rings |
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| monotrichous |
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| single tail |
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| amphitrichous |
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| tail on each end |
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| lophotrichous |
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| multiple tails from one end |
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| pertrichous |
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| multiple tails surrounding body |
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| axial filaments |
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| component responsible for locomotion of the spirochetes; wrap around cell between cell wall and cell membrane; contract and relax |
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| pili |
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| only found in gram (-) bacteria; long rigid projections; allow transfer of plasmid DNA between certain types of cells |
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| fimbrae |
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| not present in all bacteria; short, bristle-like projections; mediate attachment to one another and/or surfaces |
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| glycocalyx |
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| present in most but not all bacteria; protective outer covering; sometimes facilitates adhesion; in pathogenic bacteria, protect from the immune system; composed of polysaccharides and/or proteins |
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| slime layer of glycocalyx |
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| thin, loose covering primarily protects from loss of water or nutrients |
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| capsule of glycocalyx |
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| thick, dense covering that tightly binds to cells |
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| cell envelope |
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| structural difference in gram (-) and gram (+) cells |
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| cell wall |
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| comprised of polysaccahride peptidoglycan; prevents cell bursting in response to osmotic pressure; target of antibiotics; thick in gram (+) |
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| outer membrane |
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| only present in gram (-) bacteria; between glycocalyx and cell wall; comprised of lipopolysaccharide outside and phospholipids inside |
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| phospholipids |
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| anchor the outer membrane to the cell wall |
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| LPS |
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| lipopolysaccharide; strong antigen; illicits a string immune response; protects cells from antibacterials and disenfectants; makes gram (-) cells more difficult to kill |
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| cell membrane |
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| present in all bacteria; phospholipid bilayer with proteins dispersed (bacteria); bilayer of branched hydrocarbons (Archaea) |
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| functions of cell membrane |
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| metabolism, transport, and secretion |
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| nucleoid |
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| present in all bacteria; non-membrane bound; contains bacterial chromosome and associated proteins |
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| chromosomes |
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| tightly coiled DNA; allows storage of DNA within cell; circular; consists of thousands of genes |
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| plasmid |
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| not present in all bacteria; non-essential DNA; can fuse with chromosome; consist of a few genes; confers a growth advantage on cells; can be passed through pili and to daughter cells; important for genetic engineering |
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| ribosomes |
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| present in all bacteria; made of RNA and protein; protein synthesis; characterized by size, which is measured in svedbergs (S) |
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| svedbergs (S) |
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| measure size of ribosomes |
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| inclusion bodies |
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| not present in all bacteria; stores of nutrients, gases, etc.; enclosed by a single-layer membrane |
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| granules |
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| inclusion bodies that contain inorganic crystals and are not membrane bound |
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| cytoskeleton |
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| present in a few types of bacteria; composed of the protein actin; arranged in helical ribbons around the cell just under the membrane; contributes to cell shape and structural stability |
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| cocci |
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| sperically shaped bacteria |
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| bacilli |
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| cylindrically shaped bacteria |
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| coccobacillus |
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| bacilli; short and plump |
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| vibrio |
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| bacilli; gently curved |
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| filamentous |
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| bacilli; long and thread-like |
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| examples of spiral forms |
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| spirillium; spirochetes |
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| pleomorphism |
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| differences in the size and shape of bacteria of the same species; usually due to slight differences in cell wall structure |
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| endospores |
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| dormant form of bacteria; allows cells to withstand extremes; can remain this way for thousands of years |
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| sporulation |
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| the process of spore formation; initiated in response to depletion of nutrients from the environment; deposition of a thick protein coat around a chromosome and minimal amount of cytoplasm; protein coat made of peptidoglycan, calcium, and dipicolinic acid |
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| germination |
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| the breaking of dormancy and return to the vegetative state; occurs in presence of water and at least one other agent; can become fully metabolically active within 2 hours |
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| bacterial classification |
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| shape, arrangement, motility, growth characteristics, habitat, genetics |
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| rikettsias |
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| very small, gram (-), obligate parasites, cause Rocky Mountain spotted fever and typhus |
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| obligate parasites |
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| cannot survive, reproduce, or carry out metabolism outside the host cell |
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| chlamydias |
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| obligate parasite, cause eye infection, STD, and pneumonia |
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| cyanobacteria |
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| blue-green algae, gram (-), photosythetic and produce O2, float in water |
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| green and purple sulfur bacteria |
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| photosynthetic but don't produce O2, common in sulphur springs, freshwater lakes, and swamps |
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| mycoplasmas |
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| lack cell wall; cell membrane is more rigid due to the presence of sterols |
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| mycobacterium and nocardia |
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| cell walls do not contain peptidoglycan |
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| archaea |
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| prokaryotes in general structure; closely related to eukaryotes, rather than bacteria; unique RNA sequence; cell wall contains hydrocarbons rather than lipids |
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| thermophiles |
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| archaea that live in extreme heat |
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| halophiles |
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| archaea that live in extreme salt concentrations; contain a red pigment |
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| methanogens |
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| archaea that convert CO2 and H2 to methane gas; important for greenhouse effect |
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| psychrophiles |
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| archaea that live in extreme cold |
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| cellular arrangement of cocci |
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| single; diplococci; tetrads; sarcinae; chains; irregular clusters |
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| cellular arrangement of bacilli |
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| single; diplobacilli; streptobacilli; palisades |
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| cellular arrangement of spirilla |
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| single; short chains |
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| cellular arrangement of spirochetes |
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| single |
