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Microbiology 310 > Chapter 2 > Flashcards

Chapter 2 Flashcards

(68 cards)

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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
confocal scanning laser microscopy (CSLM)
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
26
electron microscopy
use electrons instead of photons to visualize
27
two types of electron microscopes
1. transmission electron microscopes | 2. scanning electron microscopes
28
transmission electron microscopy
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
scanning electron microscopy
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
All cells have three things in common
1. cytoplasmic membrane 2. cytoplasm 3. ribosomes
31
Eukaryotes
1. DNA in membrane bound-nucleus 2. larger and more complex 3. have organelles
32
Prokaryotes
1. no membrane enclosed organelles 2. no nucleus 3. smaller and less complex
33
viruses
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
human cell vs. E. Coli
1,000x more DNA per cell than E.Coli, 7x more genes than E.Coli
35
evolution
proces of change over time that results in new varieties and species of organisms
36
phylogeny
evolutionary relationships between organisms
37
phylogenic relationships can be deduced by...
comparing genetic information in different specimens (rRNA, ribosomal RNA, good for detecting)
38
phylogenic tree
visualization of phylogenic relationships
39
three domains
1. bacteria (prokaryotic) 2. archaea (prokaryotic) 3. eukarya (eukaryotic)
40
Archaea is more closely related to _______ than _______
eukarya, bacteria
41
eukaryotic microorganisms were ancestors of _______
multicellular organisms
42
_______ and _______ also contain their own genomes and ribosomes
mitochondria, chloroplasts
43
mitochondria & chloroplasts
1. related to specific lineages of bacteria 2. took up residence in eukarya eons ago (endosymbiosis)
44
diversity in microbial cells is product of almost _______ years of evolution
4 billion
45
chemoorganotrophs
1. obtain energy from oxidation of organic molecules 2. aerobes use oxygen to obtain energy 3. anaerobes obtain energy in absence of oxygen
46
chemolithotrophs
1. obtain energy from oxidation of inorganic molecules | 2. process found in prokaryotes only
47
phototrophs
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
autotrophs
1. use carbon dioxide as carbon source | 2. referred to as primary producers
49
heterotrophs
1. require one or more organic molecules for carbon source | 2. feed directly on autotrophs or live off products produced by autotrophs
50
extremophiles
organisms that inhabit extreme environments (hot springs, glaciers, extremely salty bodies of water, high pH environments)
51
All known pathogenic prokaryotes are...
bacteria
52
the _______ make up the largest phylum of bacteria
proteobacteria (gram negative: e.coli, pseudomonas, salmonella)
53
gram-positive phylum united by _______ and _______
phlogeny, cell wall structure (cyanobacteria)
54
green sulfur bacteria and green non-sulfur bacteria are _______
photosynthetic
55
_______ is extremely resistant to radioactivity
deinococcus
56
_______ are obligate intracellular parasites
chlamydia
57
two phyla of domain archaea
1. euryarchaeota | 2. crenarchaeota
58
euryarchaeota
1. methogens 2. extreme halophiles 3. thermoacidophiles
59
methogens
degrade organic matter anaeorbically, produce methane
60
extreme halophiles
require high salt concentrations for metabolism and reproduction
61
thermoacidophiles
grow in moderately high temperatures and low-pH environments
62
crenarchaeota
1. vast majority are hyperthermophiles | 2. live in marine, freshwater and soil systems
63
Microbial diversity is much greater than _______
laboratory culturing can reveal
64
Eukaryotic microorganisms include...
algae, fungi, protozoa, slime molds
65
protists include...
algae (phototrophic) and protozoa (not phototrophic)
66
_______ are decomposers
fungi
67
_______ and _______ have cell walls, whereas _______ and _______ do not
algae, fungi --> protozoa, slime molds
68
lichens
mutualistic relationship between two groups of protists: fungi & cyanobacteria OR fungi & algae

Microbiology 310 (4 decks)

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