Microbiology

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egjim07
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135363
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Microbiology
Updated:
2012-02-15 08:48:40
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Micro
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Exam 1
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  1. What three factors determine the quality of an optical image?
    • Magnification
    • Resolution
    • Contrast
  2. What is Snells law and what is it used to determine?
    • Snell's Law describes the relationship between the angles and the velocities of the waves(refraction) (helps determine the light ben (cureveture)
    • n1xsin(degree1)=n2xsin(unknown degree2)
    • n = index of refraction
  3. What does the index of refraction (alos called refractive index) of a substance refer to?
    • n= index of refractions
    • the speed of light in a vacuum divided the the velocity of light in that medium.
    • Where c is the speed of light and is the phase velocity. It gives the amount ofrefraction which takes place for light passing from one medium to another
  4. What do the axis,focal lenghts,and focal points of a lens describe?
    • axis - where the light rays converge
    • focal point
    • focal lengh
  5. What is real image?
    • 3 properties
    • has phisyical reality
    • it is created from converging light rays by a lens (or morror).
    • is formed when the object is outside the focal lenght of the lens
    • is upside down with respect to the object
  6. what is virtual image?
    • has only an apparent physical reality crated within the eye from diverging light rays fromed inside the focal leght of les
    • right side up with respect of the object that forms it
  7. Difference between real image and virtual image?
  8. What are the lens sytems in a modern compound microscope called? How do they work together to create the image of the speciment that you view through thr microscope?
    • Ocular: create virtual imagge
    • Objective: create a real image/reverse the image
  9. What is the difference between magnification and reolution? What are some ways of improving resolution?
    • Magnification: size
    • Resoution: Clarity
    • can improve by larger angular aperture the more light better resolution
    • Immersion oil to minimize refraction to improve image
  10. Why do we staing microorganisms? What is the difference between direct staining an indirect(negative) staining?
  11. what do the following prefixes in the metric system mean:
    Milli, Micro, and nano?
    • 1 Millimeter: mm 1/1000m = 1x10^-3
    • 1 Micrometer: um 1/100,000m = 1x10^-6
    • 1 nanometer : nm 1/1000,000,000m = 1x10^-9
  12. How do a transmission electron microscope and a scanning electron microscope differ?
    • TEM shoot electron beam through th specimen.
    • flat 2 dimensinal
    • freeze fracture
    • better resolutions
    • SEM: is below the specimen back and forth over the specimen / texture of the outside
    • overall: bothe provide different images
  13. What defines pure culture?
    • A culture containing only a single strain or species of microorganism. isolated places of growth. large number of microorganisms all descended form a single individual.
    • dilution
  14. How can we isolate a pure culture in the laboratory?
    Streak plate is a petri plate containing some type of steril nutient agar,which is used to seperate the bacteria in a mixed culture so that individuals cells can be isolated from it.
  15. What do you need to consider in selecting a culture medium to grow a particular microogranism?
    • liquid or solid medium
    • minimal defined media only nutrients for essential growth
    • complex or rich media many nutrients
    • carbon sorces
    • protein
    • notrogen
    • aerobic pr arobic media
  16. Why is agar added to microbilogical culture media and what properties does it have that make it ideal for this purpose?
    • Not used by many organisms as a nutrient source
    • good solidifing agent
    • organisms cant digest it
    • easier to handle
  17. What general characteristics distinquishes between prokaryotic and eukaryotic cells?
    eukaryotic larger size
  18. What are the most common bacterial cell shapes?
    • coccus = round
    • bacillus = longutudinal weenie
    • spirillum =wavy
    • spirochete = spiral
    • vibro= cashew shaped
    • filamentous = long hair like
  19. What are some of the special cell arrangements that can occur especially among cocci?
    • diplococci 2 cells
    • cubicpackets 8 cells
    • steptococci = long chains
    • staphylococci = grape like clusters
    • tetrads= 4 cells
  20. What are three structural components of a bacterial flagellum?
    • an ion driven motor: which can provide a torque in either direction;
    • hook: a universal joint which transmits motor torque even if it is curved
    • filament: a very long structure which acts as a
    • propeller, and behaves differently depending on which way the motor turns.
  21. In what ways does a flagellum confer motility?
    propells powered by a moter pwoered by proton motive force
  22. How can a flagella be arranged on the cell surface?
    • protein polymer of repeated subunits
    • through a complex of proteins called the hook and basal body.
  23. What is pilli(fimbriae) and what function does it have?
    • porteins straight rods that stick out of the vacteria cells
    • not as lod as flagella cells
    • helps attach to surfaces
    • comen in aquatic environments
  24. What is a capsule and what functions does it have?
    • Usually made up of polysaccharide(some Protein capsules).
    • water soluble and nonionic
    • helps protec cells from phagoctosis/drying out
    • help surface attachment/osmotic pressure barrier
    • carbon storage/ develop in harsh times
    • cell wall and envelope
  25. What does glycocalyx refer to?
    • a cup shaped structure
    • a mat of polysaccharide fibers etending from the cell surface
  26. What is the basic structure of peptidoglycan?
    • polymer of peptide linked chains of amino sugars
    • disaccharides called glycan chins corss linked with peptides of four amino acids
  27. How does the cell wall protect the cell from osmotic damage?
    • helps withstand the intracellular turgor pressure that can build up inside the cell
    • rigid network of covalent bonds protects cell form osmotic shock
  28. What are the major differences between gram negative and gram positive bacterial cell walls?
    • Gram positive: have a thick cell wall with multiple layers of peptidoglycan.
    • Cell membrane with acid
    • bacillus ,streptoccocus
    • Gram negative: have thin cell wall with one to three layers of peptidoglycan enclosed by an outer membrane (lipopolysaccheride)
    • esherichia colie
  29. What are the major antigens found in association with the cell wall are unique to gram negative or gram positive bacterial cells?
    • Gram postitive
    • teichoic acid: help retain the gram stain, a reinforement
    • s-layer: rigid flexes allows substancs to pass , pore admite molecules
    • Gram Negative: lipoprtein and lipopolusaccharide
    • murein lipoprotein endotoxin
  30. What is the structure of the bacterial cell membrane?
    • consist of phospholipid bilayer containing lipid sooluble proteins
    • hydrophopic fatty acid chains directed inwar,away from water
  31. What major functions do proteins embedded in the cell membrane have?
    • transport
    • communicaton
    • structural support
    • cell defense
  32. What different types on inclusions are found in the cytoplasm of bacterial cells and what are the functions?
    • Storage granules: starch,glycogen polyphosphate, sulfur, and polyhydraxylbutyrate
    • Gas Vesicules: provide buoyancy in some aquatic bacteria multiple vesicles stacked together form a gas vacuole
    • Carboysomes: protein shells that contain enzymes for barbon dioxide fixation by some bacteria
    • Meguetosomes: membrane, endosed, iron containing particles found magnetotactic bacteria
  33. What characteristics distingquish catabolism form biosynthesis(anabolism)?
    • catabolism: breaking down reactions(usuallu release energy ) produce energy
    • Biosynthesis(ambolism): building up reactions usually onsume energy must have energy supply.\
  34. What happens to a protein when it becomes denatured?
    disrutpion of protein structure losses its bilogical function
  35. What are the two chemicals differences between the nucleic acids RNA and DNA?
    • RNA: uracil
    • DNA: thymine
  36. What is the difference between exergonic and endergonicm chemical reactions?
    • endergonic: non spontaneous requires and external input or energy
    • Exergenic: spontaneous releases energy progress reaction
  37. What is an activaction energy?
  38. What is a catalyst?
    • it increase reation rate
    • unalterd by reaction
    • catalyst lowers the activtion energy
  39. What are the two different catergoris of cofactors?
    • metal ions: Mg2+, Zn2+, etc
    • organic coenzyme: can ve lugged in vitamins
  40. How are certain cofactors related to vitamins?
  41. How is an apoenzyme different from a holoenxyme?
    • apoenzyme: inactive protein
    • holoenzyme: active final product
  42. What is an active site of an enzyme?
    • specific sit where the enzyme can react
    • induced fit model
  43. what is allosteric site?
    • all: other
    • Steric: solid
    • resutl in enxyme slows down use either to control a pathway
    • different door way
  44. What distinguishes competitive and noncompetitive inhibition?
    • competitive inhibition: adding more substrate reverses the inhibition
    • substrate and inhibitor compete for the active site
    • Non-competitive: adding more substrate does not reverse the inhibition
    • will bond to the allosteric makes a distortion of the enzyme
    • bonding to the allosteric not the active
    • overall both slow down activity
  45. What is feedback inhibition?
    • ability to bind to th ebegining and slows down the throenin deaminase
    • there for slows metabolic pathway
    • helps regulate how muche isoleucine product you want to make
  46. beriberi
    • vitamin b1 thamine deficiency disease
    • chonic congestion mucle pain nerve damage
    • source rice
  47. pellagra
    • vitamin b3 naicin dificency
    • germtitis-fatique, comition , insomnia
  48. What is a carbohydrate?
    • CH2O
    • polysaccharides comples
    • starches,fibers, sugars
  49. What is the chemical formula of pentos monosaccharide and a hexos monosaccharide?
    • pentos = C5H10O4
    • hexos = C6H12O6
  50. In what ways are two monosaccharides are linked together and what is the resultng chemical bond between them called?
    two monosaccharides form a disaccharide through a condensation reaction to form a covalent glycosidic bond
  51. What type of structural information is represented at each level of protein?
    • Primary: amino acid sequence alpha helix
    • secondary: bending and folding over short strecthes of the polypetide Beta-strand
    • tertiery: benidn and follding over long stretches
    • quaternary: arrangements of two or more polypeptide in the protein
    • alha and beta
  52. What is a nucleotide and what three components make up the structure?
    • Nucleic acids (both RNA and DNA) are polymers
    • made up of monomers called mononucleotide units
    • pentose sugar
    • nitrogenous base
    • phosphate group

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