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Microbiology 310 > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

compound light microscope uses…

A

visible light to illuminate cells

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2
Q

_______ sets of lenses form the image. What lenses?

A

2, objective lens and ocular lens

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3
Q

Total Magnification Calculation

A

Total magnification

objective magnification x ocular magnification

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4
Q

What is the maximum magnification?

A

approximately 2000x

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5
Q

Bright-field scope

A

specimens visualized b/c of differences in contrast (density) between the specimen and its surroundings

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6
Q

resolution

A

ability to distinguish two adjacent objects as separate and distinct

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7
Q

resolution determined by…

A

wavelength of light used and numerical aperture of lens

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8
Q

resolution limit

A

0.2 micrometers

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9
Q

Four different types of light microscopy

A
  1. bright-field
  2. phase-contrast
  3. dark-field
  4. fluorescence
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10
Q

limit of resolution for light microscopy

A

0.2 micrometers

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11
Q

improving contrast results in…

A

a better final image

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12
Q

_______ improves contrast

A

staining

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13
Q

dyes

A

organic compounds that bind to specific cellular materials (methylene blue, safranin and crystal violet)

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14
Q

Gram stain

A

widely used, bacteria divided into two groups: gram-positive and gram-negative, type of differential stain

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15
Q

differential stains separate…

A

bacteria into groups

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16
Q

gram-positive bacteria appear

A

purple

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17
Q

gram-negative bacteria

A

appear red (after staining)

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18
Q

phase-contrast microscopy

A
  1. invented by Frits Zernike (1936)
  2. phase ring amplifies differences in refractive index of cell and surroundings
  3. improves contrast of a sample w/o use of stain
  4. can see live samples
  5. resulting image is dark cells on light background
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19
Q

dark-field microscopy

A
  1. light reaches specimen from sides
  2. light reaching lens is scattered by specimen
  3. image appears light on dark background
  4. excellent for observing motility
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20
Q

fluorescence microscopy

A
  1. used to visualize specimens that fluoresce

2. widely used in microbial ecology for enumerating bacteria in natural samples

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21
Q

to fluoresce

A

to emit light of one color when illuminated with another color of light

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22
Q

Cells fluoresce in two ways

A
  1. naturally (autofluorescence)

2. after being stained w/ fluorescent dye (DAPI)

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23
Q

differential interference contrast (DIC) microscopy

A
  1. uses polarizer to create 2 distinct beams of polarized light
  2. gives structures a 3D appearance (vacuoles, granules)
  3. structures not visible using bright-field are sometimes visible using DIC
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24
Q

atomic force microscopy (AFM)

A
  1. stylus placed closed to specimen to measure weak repulsive forces between it and specimen
  2. computer generates image based on stylus data
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25
Q

confocal scanning laser microscopy (CSLM)

A
  1. uses computerized microscope coupled w/ laser source to generate 3D image
  2. computer can focus laser on single layers of specimen
  3. different layers compiled for 3D image
  4. resolution = 0.1 nanometer
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26
Q

electron microscopy

A

use electrons instead of photons to visualize

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27
Q

two types of electron microscopes

A
  1. transmission electron microscopes

2. scanning electron microscopes

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28
Q

transmission electron microscopy

A
  1. electromagnets function as lenses
  2. system operates in vacuum
  3. high magnification and resolution (0.2 nm)
  4. enables visualization at molecular level
  5. specimen must be very thin and stained
29
Q

scanning electron microscopy

A
  1. specimen coated w/ thin film of heavy metal
  2. electron beam scans object
  3. scattered electrons collected by detector and image is produced
  4. large specimens can be observed
  5. magnification range of 15x-100,000x
30
Q

All cells have three things in common

A
  1. cytoplasmic membrane
  2. cytoplasm
  3. ribosomes
31
Q

Eukaryotes

A
  1. DNA in membrane bound-nucleus
  2. larger and more complex
  3. have organelles
32
Q

Prokaryotes

A
  1. no membrane enclosed organelles
  2. no nucleus
  3. smaller and less complex
33
Q

viruses

A
  1. not considered cells
  2. no metabolic abilities
  3. rely on biosynthetic machinery of infected cell
  4. infect all types of cells
  5. smallest virus is 10 nm in diameter
34
Q

human cell vs. E. Coli

A

1,000x more DNA per cell than E.Coli, 7x more genes than E.Coli

35
Q

evolution

A

proces of change over time that results in new varieties and species of organisms

36
Q

phylogeny

A

evolutionary relationships between organisms

37
Q

phylogenic relationships can be deduced by…

A

comparing genetic information in different specimens (rRNA, ribosomal RNA, good for detecting)

38
Q

phylogenic tree

A

visualization of phylogenic relationships

39
Q

three domains

A
  1. bacteria (prokaryotic)
  2. archaea (prokaryotic)
  3. eukarya (eukaryotic)
40
Q

Archaea is more closely related to _______ than _______

A

eukarya, bacteria

41
Q

eukaryotic microorganisms were ancestors of _______

A

multicellular organisms

42
Q

_______ and _______ also contain their own genomes and ribosomes

A

mitochondria, chloroplasts

43
Q

mitochondria & chloroplasts

A
  1. related to specific lineages of bacteria
  2. took up residence in eukarya eons ago
    (endosymbiosis)
44
Q

diversity in microbial cells is product of almost _______ years of evolution

45
Q

chemoorganotrophs

A
  1. obtain energy from oxidation of organic molecules
  2. aerobes use oxygen to obtain energy
  3. anaerobes obtain energy in absence of oxygen
46
Q

chemolithotrophs

A
  1. obtain energy from oxidation of inorganic molecules

2. process found in prokaryotes only

47
Q

phototrophs

A
  1. contain pigments that allow them to use light as energy source
  2. oxygenic photosynthesis produces oxygen
  3. anoxygenic photosynthesis does not produce oxygen
48
Q

autotrophs

A
  1. use carbon dioxide as carbon source

2. referred to as primary producers

49
Q

heterotrophs

A
  1. require one or more organic molecules for carbon source

2. feed directly on autotrophs or live off products produced by autotrophs

50
Q

extremophiles

A

organisms that inhabit extreme environments (hot springs, glaciers, extremely salty bodies of water, high pH environments)

51
Q

All known pathogenic prokaryotes are…

52
Q

the _______ make up the largest phylum of bacteria

A

proteobacteria (gram negative: e.coli, pseudomonas, salmonella)

53
Q

gram-positive phylum united by _______ and _______

A

phlogeny, cell wall structure (cyanobacteria)

54
Q

green sulfur bacteria and green non-sulfur bacteria are _______

A

photosynthetic

55
Q

_______ is extremely resistant to radioactivity

A

deinococcus

56
Q

_______ are obligate intracellular parasites

57
Q

two phyla of domain archaea

A
  1. euryarchaeota

2. crenarchaeota

58
Q

euryarchaeota

A
  1. methogens
  2. extreme halophiles
  3. thermoacidophiles
59
Q

methogens

A

degrade organic matter anaeorbically, produce methane

60
Q

extreme halophiles

A

require high salt concentrations for metabolism and reproduction

61
Q

thermoacidophiles

A

grow in moderately high temperatures and low-pH environments

62
Q

crenarchaeota

A
  1. vast majority are hyperthermophiles

2. live in marine, freshwater and soil systems

63
Q

Microbial diversity is much greater than _______

A

laboratory culturing can reveal

64
Q

Eukaryotic microorganisms include…

A

algae, fungi, protozoa, slime molds

65
Q

protists include…

A

algae (phototrophic) and protozoa (not phototrophic)

66
Q

_______ are decomposers

67
Q

_______ and _______ have cell walls, whereas _______ and _______ do not

A

algae, fungi –> protozoa, slime molds

68
Q

lichens

A

mutualistic relationship between two groups of protists: fungi & cyanobacteria OR fungi & algae

Microbiology 310 (4 decks)

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