Microbiology exam 1

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  1. Pleomorphism
    phenomenon where a single species takes on various shapes dependent mostly on nutrient availability
  2. Diplo-
    division in 1 plane produces cells in pairs
  3. Strepto-
    divion in 1 plane produces cells in chains
  4. Staphylo-
    random divion produces grapelike clusters
  5. (Parts of ) Functions of bacterial cell membrane
    • regulate movement of materials in and out of the cell, via charges of phsopholipids, speciliazed pore proteins and vesicle cascades
    • synthesizes cell wall components
    • assists with DNA replication
    • secretes enzymes
    • maintains osmotic membrane potential which is used to generate energy in the form of ATP
  6. (Parts of ) Functions of bacterial cell wall
    • provides a rigid backdrop for the outer membrane to be bound in gram-negative bacteria
    • prevents cell from bursting when fluids flow into the cell by osmosis
    • extremely porous and therefore cannot regulate the entry of material into the cell
  7. (Parts of ) Components of cell wall
    composed of peptidaglycan (or murrain)
  8. Outer membrane
    • found primarily in gram-negative bacteria
    • a lipid bilayer with proteins (receptors and antigens)
    • attached to the peptidaglycan by a continuous layer of small lipoproteins (proteins combed with lipids ) molecules
  9. Periplasmic space
    • gap between cell membrane and cell wall
    • generally present in gram-negative bacteria
    • area of active cell metabolism
    • contains enzymes and transport proteins
  10. (Parts of ) Functions of Outer membrane
    controls transport of some proteins through channel lproteins called porins
  11. Gram-positive bacteria
    • inner cell membrane with thick cell wall (peptidaglycan) linked by teichoic acids (serves as a passageway for movement of ions in and out of the cell)
    • no outer cell membrane and no preiplasmic space, very few lipids
    • form protoplasts on enzyme digestion of cell wall
    • may have as many 40 layers in its cell wall
    • (in cell wall) 3rd amino acid in the peptide is lysine
  12. Gram-negative bacteria
    • cell wall is thinner but more complex
    • outer membrane and perilasmic space are present
    • LPS (or endotoxin) present on outer membrane
    • form spheroplasts on enzyme digestion of cell wall
  13. Lipopolusaccharide (LPS)
    • also called endotoxin
    • integral part of the outer cell wall membrane
    • released when the bacteria dies
    • Lipid A, a component of LPS, is responsible for the toxic effects of gram-negative bacterial infection
    • highly antigenic and higly specific to a species (down to strain level)
  14. Acid-fast bacteria
    • mycobacteria
    • inner cell membrane with a very thick cell wall
    • its cell wall is comprised of thin peptidaglycan layer and thick lipid layer
    • protected by lipids from harmful effects of acids and alkalis
  15. Mycoplasma bacteria
    wall deficient, vary in shape, often forming slender branched filaments and exhibit extreme pleomorphism (vary in form even within a single culture)
  16. Granules
    • although not bounded by membrane, contain very desely packed substances
    • each granule contains a specific substance such as glycogen (energy source) or polyphosphate (used in metabolic processes)
    • phosphate granules are called volutin
    • become depleted uring starvation
  17. Vesicles
    • membrane enclose strucutres
    • rigid gas filled vesicles (vacuoles) help aquatic bacteria to float
    • lipid filled vesicles serve as storehouses of energy and source of carbon for building new molecules
  18. Conjugation pili
    long hollow tubules used to transfer DNA from 1 organism to another
  19. Attachment pili
    • fimbriae
    • short hollow tubules adhere to surfaces in order to immobilize an organism in a beneficial environment
    • contribute to the pathogenicity of certain bacteria
    • neisseria gonorrhea strains without the pili are rarely able to cause gonorrhea
  20. Glycocalyx
    layer of viscous polysaccharide material found lining the outside of cell wall
  21. Capsules
    • protective structures of very thick layers of glycocalyx, and are used during infection by pathogenic organisms
    • only certain bacteria are capable of forming capsules, and not all members of a species have capsules
  22. Slime layer
    • less tightly bound to the cell wall and is usually thinner than a capsule
    • protects cell from drying
    • helps trap nutrients near the cell
    • sometimes binds cells together
  23. Endospores
    • dormant resting stages
    • contain very little water and are highly resistant to heat, drying, acids, bases and certain disinfectants
    • depltion of nutrients induces spore formation
    • structurally, it consists of core, cortex and spore coat
    • contain dipicolinic acid and large amounts of Ca2+ which contribute to theat resistance of spores
  24. Polar monotrichous
    flagellum at 1 end
  25. Lophotrichous
    tufts of flagella at 1 or both ends
  26. Polar amphitritous
    flagellum at each end
  27. Peritrichous
    flagella all over the cell
  28. Energy capture
    • all catabolic reactions involve electron transfer, which allows energy to be captures in high energy bonds in ATP
    • oxidation
    • reduction
    • redox
  29. Autotrophic metabolism
    important for free living microorganisms--usually do not cause diseases
  30. Chemoautotrophic metabolism
    important for all infectious microorganisms
  31. Fermentation pathways
    • homolactic microbes
    • heterolactic microbes
  32. Homolactic microbes
    those that produce only lactic acid (no gas production)
  33. Heterolactic microbes
    • those that produce lactic acid, as well as other acids or alcohols and gases anre released
    • often use 5C sugars
  34. Klebsiella pneumonia
    heterolactic microbe that causes pneumonia
  35. Clostridium tetani
    heterolactic microbe that causes tetanus
  36. C. Botulinum
    Heterolactic microbe that causes botulism
  37. C. perfringens
    heterolactic microbe that is responsible for tissue damage of gangrene
  38. Lipid metabolism
    • fats are hydrolyzed to glycerol and 3 fatty acids
    • glyceril is then metabolized by glycolysis
    • fatty acids are broken down by a metabolic pathway called beta-oxidation and the products are then oxidized via the krebs cycle to obtain more energy
  39. Bacterial growth curve
    • lag phase
    • log phase
    • stationary phase
    • death phase
  40. Lag phase
    • no crease in cell number
    • cells are metabolically archive--growin in size, synthesizing enzymes, ATP and takin gin various molecules from teh medium
    • some organisms adapt to new mediaum in a day or 2 while others take several days
  41. Log phase
    • once cells adapt to the medium, poplation growth occurs in an exponential or logarithmic rate
    • generation time for most bacteria is between 20 min to 3 hrs
  42. Stationary phase
    • cell division decreases to the point that new cells are produced aat the same rate that old cells die
    • number of live cells stays constant
  43. Death phase
    • cells lose their ability divide
    • medium contains limited amounts of nutrients and may contain toxic quantities of waste material
  44. (Parts of ) Measuring bacterial growth
    • Serial dilution/Standard plate counts
    • Direct microscopic counts
    • Metabolic activity
    • Turbidity
  45. Serial dilution/Standard plate counts
    sample is serially diulted by orders of magnitude (10x) in molten agar or water and then poured or streaked onto plates, respectively
  46. Direct microscopic counts
    samples can be applied to a petroff-hausser counting chaber and cell can be directly counted as they are
  47. Turbidity
    • cloudy appearance indicates the presence of organisms
    • estimates of growht can be measure using a spectrophotometer
  48. Metabolic activity
    • indirect way to estimate bacterial growth
    • rate at which metabolic products such as gases and/or acids are formed b culure reflects the mass of bacteria
    • gas production can be detected by capturing the gas in small inverted Durham tubes placed in larger tubes of liquid medium containing bacteria
    • acid production can be detected by incorporating pH indicators
  49. Physical factors affecting bacterial growth
    • pH
    • temperature
    • oxygen
    • moisture
    • osmotic pressure
    • nutritional factors
  50. Endoenzymes
    exist inside the cytoplasm
  51. Periplasmic enzymes
    exist inside the periplasmic space in gram-negative bacteria
  52. Exoenzymes
    • exist outside the cell
    • specialized nezymes that are prodded by the cell to break down compounds that are too large to diffuse through the cell membrane into smaller ones that can
  53. Defined media
    those which are made with specific amounts of specific compounds
  54. Comples (or undefined) media
    • those which contain extracts and digests instead of specific compounds
    • eg. yeast extract, peptone
  55. Selective media
    specialized media that encourages growth of somebacteria but discourages growth of others
  56. Differential media
    specialized media that has a constituent that causes a visible change in the medium (color of pH) dependign on the metabolic activities of the organism, thus differentiating it from others
  57. Enrichment media
    specialized media that encourages growth of a specific bacteria without discouraging growth of other bacteria
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Microbiology exam 1
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