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Microbiology > Ch 2 > Flashcards

Ch 2 Flashcards

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Biology 101 flashcards
1
Q

___ ___ microscopes uses visible light to illuminate cells.

A

Compound light

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2
Q

Many different types of light microscopy:

A
  • bright-field
  • phase-contrast
  • dark-field
  • flourescence
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3
Q

Bright-field scope:

A

Specimens are visualized because of differences in contrast between specimen and surroundings

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4
Q

Two sets of lenses form the image:

A

Objective lens

Ocular lens

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5
Q

Total magnification=

A

Objective magnification x ocular magnification

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6
Q

Magnification:

A

The ability to make an object larger

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7
Q

Resolution:

A

The ability to distinguish two adjacent objects as separate and distinct

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8
Q

___ is determined by the wavelength of light used and numerical aperture of lens.

A

Resolution

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9
Q

Limit of resolution for light microscope is about ___.

A

2 um

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10
Q

Improving ___ results in a better final image.

A

Contrast

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11
Q

___ improves contrast.

A

Staining

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12
Q

___ are organic compounds that bind to specific cellular materials.

A

Dyes

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13
Q

Examples of common stains are:

A
  • methylene blue
  • safranin
  • crystal violet
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14
Q

Differential stains:

A

The gram stain

  • separate bacteria into groups
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15
Q

Bacteria can be divided into two major groups:

A

Gram-positive and gram-negative

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16
Q

Gram-positive bacteria appear ___, and gram-negative bacteria appear ___ after staining.

A

Purple, red

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17
Q

Phase-contrast microscopy

A
  • phase ring amplifies differences in the refractive index of cell and surroundings
  • improves the contrast of a sample without the use of a stain
  • allows for visualization of live samples
  • resulting image is dark cells on a light background
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18
Q

Dark-field microscopy

A
  • light reaches the specimen from the sides
  • light reaching the lens has been scattered by specimen
  • image appears light on a dark background
  • excellent for observing motility and spirochaetes
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19
Q

Fluorescence microscopy

A
  • used to visualize specimens that flouresce
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20
Q

Fluoresce

A

Emit light of one color when illuminated with another color of light

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21
Q

Autofluorescence

A

Cells fluoresce naturally or after they have been stained with a fluorescent dye such as DAPI

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22
Q

Electron microscopes uses ___ instead of ___ to image cells and structures

A

Electrons, photons

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23
Q

Two types of electron microscopes:

A

Transmission electron microscope

Scanning electron microscope

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24
Q

Transmission electron microscope (TEM)

A
  • electromagnets function as lenses
  • system operates in a vacuum
  • high magnification and resolution (.2nm)
  • enables visualization of structures at the molecular level
  • specimen must be very thin and be stained
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25
Q

Scanning electron microscopy (SEM)

A
  • specimen is coated with a thin film of heavy metal
  • an electron beam scans the object
  • scattered electrons are collected by a detector, and an image is produced
  • even very large specimens can be observed
  • magnification range of 15X-100,000X
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26
Q

Morphology:

A

Cell shape

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27
Q

Coccus

A

Spherical or ovoid

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28
Q

Rod

A

Cylindrical shape

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29
Q

Spirillum

A

Spiral shape

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30
Q

Size range for prokaryotes:

A

.2 um to 700 um in diameter

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31
Q

Size range for eukaryotic cells:

A

10 to 200 um in diameter

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32
Q

Cytoplasmic membrane

A
  • thin structure that surrounds the cell
  • vital barrier that separates cytoplasm from environment
  • highly selective permeable barrier; enables concentration of specific metabolites and excretion of waste products
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33
Q

Composition of membranes

General structure is ___ ___

A

Phospholipid bilayer

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34
Q

Can exist in many different chemical forms as a result of variation in the groups attached to the ___ ___.

A

Glycerol backbone

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35
Q

Fatty acids point inward to form ___ ___; hydrophilic portions remain exposed to ___ ___ or the cytoplasm.

A

Hydrophobic environment; external environment

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36
Q

Integral membrane proteins

A

Firmly embedded in the membrane

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37
Q

Peripheral membrane proteins

A

One portion anchored in the membrane

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38
Q

___ linkages in phospholipids of archaea.

A

Ether

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39
Q

Bacteria and Eukarya that have ___ linkages in phospholipids.

A

Ester

40
Q

Archaeal lipids lack ___ ___; have ___ instead.

A

Fatty acids; isoprenes

41
Q

Permeability barrier

A
  • polar and charged molecules must be transported

- transport proteins accumulate solutes against the concentration gradient

42
Q

Protein anchor

A

Holds transport proteins in place

43
Q

Energy conservation

A

Generation of proton motive force

44
Q

Three transport events are possible:

A

Uniport, symport, and antiport

45
Q

Uniporters

A

Transport in one direction across the membrane

46
Q

Symporters

A

Function as co-transporters

47
Q

Antiporters

A

Transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction

48
Q

Gram-negative cell wall

A

Two layers: LPS and peptidoglycan

49
Q

Gram-positive cell wall

A

One layer: peptidoglycan

50
Q

Peptidoglycan

A

Rigid layer that provides strength to cell wall

51
Q

Polysaccharide composed of:

A
  • N-acetylglucosamine and N-acetylmuramic acid
  • amino acids
  • cross-linked differently in gram-negative bacteria and gram-positive bacteria
52
Q

Gram-positive cell walls can contain up to ___ peptidoglycan

A

90%

53
Q

Teichoic acids

A

Acidic substances

54
Q

Lipoteichoic acids

A

Teichoic acids covalently bound to membrane lipids

55
Q

Common to have ___ ___ embedded in gram-positive cell walls

A

Teichoic acids

56
Q

Prokaryotes that lack cell walls

A
  • mycoplasmas

- Thermoplasma

57
Q

Mycoplasmas

A

Group of pathogenic bacteria

58
Q

Thermoplasma

A

Species of archaea

59
Q

Most of cell wall composed of ___ ___, aka lipopolysaccharide (LPS) layer

A

Outer membrane

60
Q

LPS consists of ___ ___ and ___

A

Core polysaccharide and O-polysaccharide

61
Q

Endotoxin

A

The toxic component of LPS

62
Q

Periplasm

A

Space located between cytoplasmic and outer membrane

63
Q

Porins

A

Channels for movement of hydrophilic low-molecular-weight substances

64
Q

Capsules and slime layers

A
  • assist in attachment to surfaces
  • protect against phagocytosis
  • resist desiccation
65
Q

Fimbriae

A
  • filamentous protein structures

- enable organisms to stick to surfaces, form pellicles, or biofilms on solid surfaces

66
Q

Pellicles

A

Thin sheets of cells on a liquid surface

67
Q

Pili

A
  • filamentous protein structures
  • typically longer than Fimbriae
  • assist in surface attachment
  • facilitate genetic exchange between cells
68
Q

Conjugation

A

Exchange between cells

69
Q

Endospores

A
  • highly differentiated cells resistant to heat, harsh chemicals, and radiation
  • “dormant” stage of bacterial life cycle
  • ideal for dispersal via wind, water, or animal gut
  • present only in some gram-positive bacteria
70
Q

Flagella

A

Structure that assists in swimming

  • peritrichous, polar, lophotrichous
  • helical in shape
71
Q

Flagellar structure of bacteria

A
  • filament composed of Flagellin

- move by rotation

72
Q

Peritrichously flagellated cells

A

Move slowly in a straight line

73
Q

Polarly flagellated cells

A

Move more rapidly and typically spin around

74
Q

Chemotaxis

A

Best studied in E. coli
“Run and tumble” behavior

Bacteria respond to temporal difference in chemical concentration

75
Q

Attractants and receptors sensed by ___.

A

Chemoreceptors

76
Q

Bright-field used to look at..

A

Dead, stained organisms

77
Q

Phase contrast and dark field used to look at..

A

Living organisms

78
Q

Basic stain/dye

A

+ charge

79
Q

Acidic stain/dye

A
  • charge
80
Q

___ ___ will allow us to see the capsule

A

Negative stain

81
Q

Simple stain

A

Stains cells all one color

82
Q

Thick peptidoglycan layer

A

Gram +

83
Q

Thin peptidoglycan layer

A

Gram -

84
Q

Streptococcus

A

Chain

85
Q

Staphylococcus

A

Cluster

86
Q

Vibrio usually ..

A

Curve shaped rod

87
Q

Monotrichous or polar flagellum

A

One single flagella

88
Q

Lophotrichous

A

Few flagella on one side

89
Q

Amphitrichous

A

Few flagella on opposite ends

90
Q

Peritrichous

A

Flagella all around

91
Q

Largest we will look at

A

Bacillus sabtilis

Large gram - rod

92
Q

Smallest we will look at

A

Streptococcus

Gram + cocci

93
Q

Passive transport

A

High -> low

Doesn’t need ATP

94
Q

Active transport

A

Low -> high

ATP is required

95
Q

Bacillus and Claustrudium

A

Both gram + rods
Bacillus needs oxygen
Claustrudium hates oxygen

Microbiology (26 decks)

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