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Biosci 3313: Microbiology > Exam 1 > Flashcards

Exam 1 Flashcards

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1
Q

What are some ways microorganism affect life?

A

Microbiome in gut, pathogens, foods, digest food, break down toxins, study, model for early life, source of all life, very diverse/abundant, grow everywhere, affect geosphere/climate, symbiotes, industrial - genetic engineering, source of enzymes

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2
Q

Meaning of ATCC

A

American Type Culture Collection

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3
Q

PAMPs and MAMPs

A

Pathogen Associated Molecular Patterns are now referred to as Microbial Associated Molecular Patterns
highlight that microbes can have beneficial or negative roles

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4
Q

Why are vertebrate immune systems more complex than invertebrates? (Margaret McFall-Ngai

A

They have a longer lifespan and have the opportunity and necessity to develop that way

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5
Q

Meaning of LUCA

A

last universal common ancestor

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6
Q

3 Domains of Life

A

bacteria, archaea, eukarya

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7
Q

Conditions on earth during heavy bombardment

A

no water, high temperatures, reduced gases in the environment

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8
Q

What are stromatolites? How old are they? Where are they found?

A

Fossils greater than 3.5 BYA found during the 1950s in intertidal marine areas
Mats of mostly photosynthetic organisms
Some are still found in Australia today

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9
Q

The oldest eukaryotes are __________

A

2.5 MYA

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10
Q

The oldest bacteria are _____________

A

3.5 BYA

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11
Q

The earliest branches of the Tree of Life contain _____________ bacteria

A

thermophilic

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12
Q

When did microbiology as a scientific discipline begin?

A

People began linking specific microbes to disease in the 1800s, partially due to the development of agar plates allowing separation of microbes
In the 1850’s people thought disease was caused by “bad air”

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13
Q

Three Eras of the Science of Microbiology?

A

Pre-Germ Theory, Golden Age, Modern Era

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14
Q

Contribution to Microbiology: Francisco Redi

A

cheesecloth over meat, disprove spontaneous generation

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15
Q

Contribution to Microbiology: Antoni van Leeuwenhoek

A

first microscope, discovered animalcules/microorganisms

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16
Q

Contribution to Microbiology: Edward Jenner

A

cowpox (cowpox victims were immune)

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17
Q

Contribution to Microbiology: Ignaz Semmelweis

A

childbed fever, pregnant women, handwashing

Women who delivered babies in hospitals
died more often

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18
Q

Contribution to Microbiology: John Snow

A

ghost map, cholera, father of epidemiology

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19
Q

Contribution to Microbiology: Louis Pasteur

A

disprove spontaneous generation, swan flask

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20
Q

Contribution to Microbiology: Joseph Lister

A

disinfectant before surgery

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21
Q

Contribution to Microbiology: Robert Koch

A

germ theory, 4 postulates, causative agents of anthrax and tuberculosis

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22
Q

4 Postulates and their purpose

A

Observe, Isolate, Infect, Reisolate

1st (Observe): Make the observation
Pts with tb have a particular microorganism associated with them
2nd (Isolate): Isolate that organism in pure culture
Possible with agar plates
3rd (Infect): Infect an individual with the purified organism
4th (Reisolate): Reisolate the same organism from the infected individual

Demonstrate that a disease is caused by a microorganism

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23
Q

Germ Theory

A

Germ Theory: A disease-causing microorganism should be present in animals infected by the disease and not in healthy animals

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24
Q

Contribution to Microbiology: Fannie Hesse

A

agar plates (instead of gelatin)

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25
Q

Contribution to Microbiology: Hans Christian Gram

A

gram stain (1st differential stain)

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26
Q

Contribution to Microbiology: Sergei Winogradsky

A

principles of chemolithotrophy, Winogradsky column

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27
Q

Contribution to Microbiology: Martinus Beijerink

A

virus and enrichment techniques

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28
Q

Contribution to Microbiology: Beatrix Potter

A

mycologist

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29
Q

Contribution to Microbiology: Paul Ehrlich

A

chemotherapy (salvarsan)

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30
Q

Contribution to Microbiology: AJ Kluyver

A

comparative biochemistry

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31
Q

Contribution to Microbiology: Alexander Fleming, Howard Florey, and Ernst Chain

A

penicillin, mold that grew on agar petri dish killed bacteria on the same agar

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32
Q

Contribution to Microbiology: Alice Evens

A

pasteurization of milk

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33
Q

Contribution to Microbiology: Rebecca Lancefield

A

serotyping streptococci

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34
Q

Contribution to Microbiology: Selman Waksman

A

streptomycin

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35
Q

Contribution to Microbiology: Oswald Avery, Colin MacLeod, Maclyn McCarty

A

identify deoxyribonucleic acid (DNA) as the “transforming principle” responsible for specific characteristics in bacteria

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36
Q

How do microscopes work?

A

light bends as it passes through substances of different densities

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37
Q

Define resolving power

A

distance between two objects that can be separated by the lens in the formation of an image

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38
Q

Better Resolving Power = wavelength, refractive index, angular aperture

A

shorter wavelength (purple/UV)
high refractive index
higher angular aperture

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39
Q

Describe chromatic aberrations of microscopes

A

Different wavelengths focus at different places

Due to combining lenses of different shape and composition

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40
Q

Describe spherical aberrations of microscopes

A

Light rays at periphery focus at a different place from the rays at the center

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41
Q

Describe a darkfield microscope

A

dark background, structures of cells stand out

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42
Q

Describe a phase-contrast microscope

A

enhance contrast of cells and their medium
Denser objects appear darker (extremely dense is white)
More contrasts lends a 3D look

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43
Q

What is unique about fluorescence microscopy?

A

uses dyes and antibodies

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44
Q

Describe a confocal scanning microscope and what they are used for

A

See where cells are in tissues and how they move

Visual cells, 3D structures

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45
Q

Describe electron microscopes (general)

A

very high magnification, only dead organisms, need coating, black and white

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46
Q

What is a SEM microscope? How is it used?

A

Scanning electron microscope

Surface only

47
Q

What is a TEM microscope? How is it used?

A

Transmission Electron microscope

3D, thin slice of material, internal structures

48
Q

Describe a Nermaski microscope

A

Behaves like SEM
surface structures
3D appearance

49
Q

Term for rod

A

bacillus

50
Q

Term for round

A

coccus

51
Q

Term for short rod (different from rod)

A

coccobacillus

52
Q

Term for spiral

A

spirillum

53
Q

Term for curved rod (different from short rod)

A

vibrio

54
Q

Term for long, loose, helical spiral

A

spirochete

55
Q

What would you call a joined pair of cocci?

A

diplococcus

56
Q

What would you call a cube of cocci?

A

tetrad

57
Q

What would you call a cluster of cocci?

A

staphylococcus

58
Q

What would you call a chain of rods?

A

streptobacillus

59
Q

Define inclusions

A

Structures inside the cell used for storage, detoxification, and movement

60
Q

What is poly-beta-hydroxybutyrate?

A

a compound used for carbon storage that can be used for biodegradable plastic

61
Q

What is the purpose of gas vesicles?

A

allow aquatic microorganisms to modify their density

62
Q

What are stains used for?

A

Increase contrast, distinguish bacteria, see subcellular structures

63
Q

What is the difference between acidic and basic stains?

A

Basic dyes stain negatively charged membranes, acidic dyes stain the surroundings of negatively charged membranes

64
Q

What is the difference between simple stains and differential stains?

A

Gram stain is a differential stain, organisms act differentially in differential stains depending on the strain

65
Q

What are specialized stains for?

A

Detect specific cellular components (such as flagella)

66
Q

What are the four steps of a Gram stain? Which is most important?

A

1st Primary stain- prepare smear -> Both cells stained purple
Take cells and smear with water, then let dry.
Crystal violet stain first (stains every bacterial cell)

2nd Mordant- flood preparation
Iodine solution that intensifies the purple

3rd Decolorization- add ethanol -> Dye washes off gram-negative

4th Counterstain- stain with safranin
To see the gram negative bacteria (which are now clear), add safranin

3rd step is most important, will have controls to test the method

67
Q

What are some functions of prokaryotic surfaces?

A

Cell-cell contact, non-specific binding, holding shape, cation/anion binding, protection, molecular sieve

68
Q

What are pili/fimbrae?

A

rods that help bacteria attach to surfaces

69
Q

What is a capsule/slime layer/biofilm? What is it for?

A

polysaccharide layers outside of the cell wall/membrane (also called glycocalyx)

Can help attachment to surfaces, prevent desiccation, or provide protection

70
Q

What are some of the purposes of the cytoplasmic/plasma membrane?

A

Provide a selective barrier between the cell wall and internal structures
Site of photosynthesis (bacteria), DNA replication, and enzyme reactions
Small hydrophobic molecules pass through the best

71
Q

Gram-Negative vs Gram-Positive: Peptidoglycan layer

A

thin in negative, thick in positive

72
Q

Gram-Negative vs Gram-Positive: presence of lipoteichoic acid

A

absent in negative, present in peptidoglycan wall of positive

73
Q

Gram-Negative vs Gram-Positive: presence of outer (secondary) layer

A

present in negative, absent in positive (more susceptible to attacks on peptidoglycan wall)

74
Q

Gram-Negative vs Gram-Positive: presence of periplasmic space

A

present in negative (between 2 membranes), absent in positive

75
Q

Gram-Negative vs Gram-Positive: tetrapeptide chain components

A

meso-diaminopimelic acid in negative, L-lysine in positive

76
Q

Gram-Negative vs Gram-Positive: linkage between tetrapeptide chains

A

direct in negative, pentapeptide in positive

77
Q

What are the special components of the outer membrane of gram-negative bacteria?

A

Outer membrane containing “lipid A”, which is linked by sugar to an O polysaccharide (repeating sequence, varies between cells)
Whole thing called a lipopolysaccharide (LPS)
Lipid A is toxic

78
Q

What are the sugars that both gram-negative and gram-positive contain in their cell walls?

A

NAG and NAM

79
Q

What allows packaging of chromosomal DNA?

A

supercoiling

80
Q

How are archaea different from bacteria (cell wall)?

A

Many lack a cell wall
Never contain peptidoglycan (also called murein)
May have pseudomurein or protein cell walls (S-layer)

81
Q

What is the purpose of an endospore?

A

Formed due to lack of nutrients, toxins, certain types of cell-cell contact, and other types of stress
Protects from desiccation, heat, chemicals (including immune system), UV radiation, high refractivity
Metabolically inert

82
Q

How are endospores produced?

A

A special type of asymmetrical reproduction called sporulation
Cell begins to reproduce asymmetrically → larger portion “engulfs” smaller portion → cell lyses → free endospore then removes a lot of liquid and produces proteins to make its exosporium, spore coat, core wall, and cortex

83
Q

How can endospores be used in differentiating bacteria?

A

ability to make one, its size, its location

84
Q

Describe the prokaryotic flagella

A

pure protein, solid/stable, very long, move by roatation

85
Q

What are the parts of a prokaryotic flagella?

A

basal body, hook, filament

86
Q

What is the term for a tuft of flagella?

A

loctricus

87
Q

What is the term for flagella all over?

A

peritrichous

88
Q

What is the term for two or more polar flagella?

A

lophotrichous

89
Q

How do bacteria move? (general)

A

Without any stimulus bacteria will move until they reach equilibrium, stay near favorable areas and leave unfavorable areas, move by either tumbling or running

90
Q

Describe a bacteria “run”. How is it used to move bacteria to a better location?

A

use flagella to move in a specific direction

If there is an attractant present they will extend their run and if there is a toxin they will shorten their run

91
Q

Describe a bacteria “tumble”. Why do they do that?

A

throw out their flagella and float randomly

they have to keep sensing, bacteria are always trying to sense their environment

92
Q

Describe a hemocytometer or a petroff-hausser slide

A

A special slide designed for counting the bacterial cells in a measured volume of sample

Easy to use, fast, inexpensive

93
Q

What are the limitations of cell counting via hemocytometer?

A

Cannot distinguish live/dead, overlook small cells, imprecise (esp. low densities)

94
Q

How does a coulter counter work? What are its limitations?

A

Counts cells by measuring change in resistance in a solution when a cell passes through a small opening

Rapid and accurate up to certain concentrations
Does not differentiate between live/dead cells

95
Q

Describe the spread-plate method

A

Sample is pipetted onto agar and spread

96
Q

Describe the pour-plate method

A

Sample is pipetted into plate, then medium is added

Volumes greater than .1 mL

97
Q

What range of cells can be reliably counted?

A

30-300 cells/colonies, units are CFU/mL

98
Q

What are the advantages and disadvantages of plate counting?

A

most accurate method (slightly low), but it requires a lot of plates, time, and effort

99
Q

How are cells counted with a spectrophotometer?

A

Measured with a spectrophotometer with units as OD600

Rapid, can measure change over time easily, need a minimum concentration of cells

As long as above min, equally accurate at low + midrange

Usually plotted on a semi-log scale

100
Q

Define growth

A

Increase in microbial mass indicates a change in the number of cells in a given locale

101
Q

What is the equation to determine the number of generations needed to reach a certain population size?

A

Nn = N0 * 2^n

Nn is the number of cells at any generation n
N0 is the initial number of cells
n is the number of generations

102
Q

What are the four phases of bacterial growth?

A

lag, exponential/lag, stationary, death

103
Q

Describe the lag phase of cell growth

A

no cell division

Cells grow larger and are metabolically active, synthesizing proteins and making repairs

104
Q

Describe the exponential/log phase of cell growth

A

generation time constant

Used for experiments to determine growth rate in prime conditions

105
Q

Describe the stationary phase of cell growth

A

reproduction/death balanced

May have more cells (than exp/log), but many will be dead
Amount of viable cells remain the same

106
Q

Describe the death phase of cell growth

A

death exceeds reproduction exponentially

107
Q

Describe rich/complex media

A

Not all ingredients defined (yeast extract, peptone, tryptone), supports growth of a wide range of bacteria

108
Q

Describe enriched media

A

contains added essential nutrients specific organisms need to grow

109
Q

Describe enrichment cultures

A

preferred growth of desired microorganism followed by growth in selective media

110
Q

Describe fastidious organisms

A

cannot make certain nutrients and require them to be added to their media

111
Q

Describe chemically defined media

A

Identity/quantity of all contents known
Supports growth of fewer numbers of bacteria
Types dependent on carbon source

112
Q

Describe selective media

A

Discourages the growth of specific types of organisms

Usually contains ingredients such as antibiotics, dyes, detergents, or salts

113
Q

Define streak plating

A

procedure that uses inoculating loops to isolate a pure culture of a bacterium from a mixture

114
Q

Describe differential media

A

Certain organisms will acquire a specific appearance

Usually contains pH indicator dyes or cleaveable color-changing substrates

Biosci 3313: Microbiology (4 decks)

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