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Microbiology > Chapter 1: The Microbial World > Flashcards

Chapter 1: The Microbial World Flashcards

1
Q

the total compliment of microbial cells in and on your body

A

microbiome

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2
Q

life forms too small to be seen by the human eye

A

microorganisms

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3
Q

microbial communities

A

where microorganisms typically live

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4
Q

a collection of cells that have been grown in or on a nutrient medium

A

culture

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5
Q

liquid or solid nutrient mixture that contains all of the nutrients required for a microorganism to grow

A

medium

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6
Q

increase in cell number as a result of cell division

A

growth

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7
Q

a visible colony happens after….

A

a single microbial cell is place on a solid nutrient medium that grows and divides.

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8
Q

the cells permeability barrier

A

cytoplasmic membrane

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9
Q

aqueous mixture of macromolecules ( proteins, lipids, nucleic acids, polysaccharides), small organic molecules, various inorganic ions, and ribosomes.

A

cytoplasm

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10
Q

structures responsible for protein synthesis in all cells

A

ribosomes

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11
Q

some cells have a ____ _____ that lends structural strength for the cell

A

cell wall

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12
Q

T/F plant cells and most microorganisms have cell walls, whereas animal cells typically do not

A

true

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13
Q

what are the two major structural classes of cells:

A

prokaryotic cells

eukaryotic cells

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14
Q

eukaryotic cells are found in the _______ domain ______.

A

phylogenic; Eukarya

includes plants and animals as well as diverse microbial eukaryotes such as algae, protozoa, and fungi.

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15
Q

membrane enclosed cytoplasmic structures are called:

A

organelles

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16
Q

prokaryotic cells are found in the domains ____ and _____

A

bacteria; archaea

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17
Q

How are prokaryotic cells different than eukaryotic cells?

A

They are much simpler and have few internal structures.

  • contain plasmids
  • have no nucleus
  • typically lack organelles
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18
Q

what is the genome?

A

the complement of all genes in a cell.
the living blueprint of an organism; the characteristics, activities and very survival of a cell are governed by its genome.

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19
Q

what is a gene?

A

a segment of DNA that encodes a protein or an RNA molecule.

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20
Q

How do the genomes differ in prokaryotic cells vs eukaryotic cells?

A

Prokaryotic cells: the genomes are typically closed circular chromosomes (some prokaryotes have linear genomes), within the nucleoid.
Eukaryotic cells: the DNA is situated as several linear molecules within the membrane enclosed nucleus.

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21
Q

a mass visible with a microscope in prokaryote cells is referred to as the

A

nucleoid

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22
Q

t/f most prokaryotic cells only have a single chromosome but many also contain one of more small circles of DNA distinct from that of the chromosome

A

True

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23
Q

what is a plasmid?

A

small circles of DNA in prokaryotic cells that is distinct from the chromosome.

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24
Q

fun fact: plasmids typically contain genes that are not essential and confer some special property on the cell (unique metabolism or antibiotic resistance of some kind)

A

freebee

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25
Q

proteins that have catalytic activity

A

enzymes

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26
Q

when are enzymes and other proteins synthesized?

A

during gene expression in the sequential process of transcription and translation

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27
Q

all cells show some form of ________ by taking up nutrients from the environment and transforming them into new cell materials and waste products.

A

metabolism

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28
Q

What is transcription?

A

the process by which the information on DNA is copied into an RNA molecule.

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29
Q

What is translation?

A

the process whereby the information on an RNA molecule is used by a ribosome to synthesize a protein.

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30
Q

microbial growth requires replication through the process of ____ _________.

A

DNA replication

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31
Q

self-propulsion is another word for

A

motility

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32
Q

some cells undergo the process of differentiation which results in:

A

the formation of modified cells specialized for growth, dispersal, or survival.

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33
Q

All cells have these 3 properties:

A
  • metabolism (catalytic & genetic)
  • growth
  • evolution
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34
Q

Only some cells have these 4 different properties:

A
  • differentiation
  • communication
  • genetic exchange
  • motility
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35
Q

the ability for cells to be “aware” of their neighbors and act accordingly:

A

intercellular communcation

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36
Q

the process of horizontal gene transfer occurs when

A

some prokaryotic cells exchange genes with neighboring cells, either of the same or a different species.

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37
Q

the term used what genes in a population of cells change in sequence and frequency over time, leading to descent with modification

A

Evolution

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38
Q

t/f microorganisms evolve very very slowly compared to the evolution of plants and animals.

A

false, they evolve much quicker than plants and animals

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39
Q

History of earth and microbial cells:

A
  • Earth is 4.6 billion years old
  • first microbial cells appeared between 3.8 and 4.3 billion years ago
  • 1st 2 billion years of earth’s existence was anoxic.
  • anaerobic phototrophic microorganisms evolved
  • cyanobacteria (aerobic phototrophs) evolved
  • after oxygenation of earth, multicellular life forms began to exist
  • plants and animals have only existed for about half a billion years.
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40
Q

where did early phototrophs live? do these structures still exist today?

A

microbial mats; yes

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41
Q

t/f 80% of lifes history was exclusively microbial

A

true

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42
Q

t/f all known cellular organisms belong to 1/3 major domains. What are these domains?

A

true,

bacteria, archaea, and the eukarya

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43
Q

fun fact: approximately 60 genes are universally present in cells of all 3 major domains

A

freebee

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44
Q

all three domains have descended from what?

A

the last universal common ancestor (LUCA)

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45
Q

what is the estimated about of microbial cells on earth?

A

2 x 10^30

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46
Q

what are extremophiles?

A

microbes that are abundant in habitats that are much too harsh for other forms of life.

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47
Q

name 3 examples of places extremophiles live:

A
  • glaciers
  • volcanic hot springs
  • high salt environments
  • acidic environments
  • alkaline environments
  • areas of extreme pressure
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48
Q

the consideration of the ways in which microorganisms affect animals, plants and the entire global ecosystem:

A

microbial ecology

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49
Q

at the beginning of the 20th century, the major cause of death was:

A

pathogens

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50
Q

the extremophile that can live in high heat is termed:

A

hyperthermophile

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51
Q

the extremophile that can live in very cold temperatures is termed:

A

psychrophile

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52
Q

the extremophile that can survive at an extremely low pH:

A

acidophile

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53
Q

the extremophile that can survive at an extremely high pH:

A

alkaliphile

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54
Q

the extremophile that can survive at extremely high pressure is:

A

barophile (piezophile)

55
Q

the extremophile that lives in salt is called

A

a halophile

56
Q

what are some examples of foods that are improved and aided by microbes?

A
  • yogurt
  • cheeses
  • buttermilk
57
Q

microbes help agriculture how?

A

nitration fixation

58
Q

how do microbes aid in human nutrition?

A

being present in the gut microbiome to help aid in digestion of complex carbohydrates and synthesize vitamins and other nutrients that are essential to host nutrition.

59
Q

what are microbes that grow on submerged surfaces called?

A

biofilms

60
Q

where can biofilms be found?

A
  • ships
  • factories and pipelines
  • sewers
  • implanted medical devices
61
Q

How does industrial microbiology produce valuable products?

A

Naturally occurring microorganisms are grown on a massive scale to make thins such as antibiotics, enzymes, and chemicals at low cost in mass amounts.

62
Q

How does biotechnology produce valuable products?

A

Biotechnology employs genetically engineered microorganisms to make products of high value such as insulin, human proteins etc. (low scale)

63
Q

What is a biofuel?

A

a microorganism engineered fuel. Examples include:

  • methane (CH4)
  • Ethyl Alcohol (ethanol)
64
Q

t/f microorganisms can convert waste material, such as animal wastes, cellulose and domestic refuse into biofuels

A

true

65
Q

In what other ways can microorganisms be beneficial?

A
  • wastewater treatment: battling cholera and typhoid

- bioremediation: process of cleaning up industrial pollution

66
Q

Who was the inventor of the microscope and the first person to see bacteria?

A

Antoni van Leeuwenhoek

67
Q

What type of microscope did Leeuwenhoek invent?

A

light microscope with a simple lens that could magnify an image at least 266x

68
Q

what term describes the capacity of a microscope to enlarge and image?

A

magnification

69
Q

what term refers to the ability to distinguish two adjacent objects as distinct and separate?

A

resolution

70
Q

What governs our ability to see the very small?

A

resolution

71
Q

what is the limit of resolution for a light microscope?

A

about .2 micrometers.

this means that two objects that are closer together than .2 micrometers cannot be resolves as distinct and separate.

72
Q

what are the 5 types of light microscopy?

A
  • bright-field
  • phase contrast
  • differential interference contrast
  • dark-field
  • fluorescence
73
Q

fun fact: with the modern compound light microscope, light from a light source is focused on the specimen by the condenser, this light passes through the sample and is collected by the lenses

A

freebee

74
Q

what are the two types of lenses and what are their magnifications?

A
  • ocular: magnifies 10-30x

- objective: magnify 10-100x

75
Q

what is the total magnification of a microscope?

A

the producct of the magnification of its objective and ocular lenses.

76
Q

fun fact: 1000x is required to resolve objects .2 micrometers in diameter. this is the limit. magnification beyond this provides little improvement

A

freebee

77
Q

lenses on which oil is used are called ___ _______ _____

A

oil immersion lenses

78
Q

Immersion lenses work by ____

A

increasing the light gathering ability of a lens, which means it increases the amount of light that is collected and viewed by the lens.

79
Q

specimen are visualized because of differences in _____ that exist between them and their surroundings

A

contrast

80
Q

How does contrast result in bright-field microscopy?

A

contrast results when cells absorb or scatter light differently from their surroundings.

81
Q

Why are bacterial cells difficult to see in bright-field microscopy?

A

because bacterial cells typically lack contrast, that is, their optical properties are similar to the surrounding medium, which makes them difficult to see with this microscope.

82
Q

How do we increase the contrast when viewing bacteria with a bright-field microscope?

A

staining

83
Q

What is a basic dye?

A

Positively charge dyes.

84
Q

what are three examples of basic dyes?

A
  • methylene blue
  • crystal violet
  • safranin
85
Q

How do basic dyes work?

A
  • by binding strongly to negatively charged cell components such as nucleic acids and acidic polysaccharides.
  • these dyes also stain the surfaces of cells because cell surfaces are typically negatively charged
86
Q

what is the procedure for staining cells for observation?

A
  1. Preparing a smear:
    - spread culture in thin film over slide
    - dry in air
  2. Heat fixing and staining
    - pass slide through flame to heat fix
    - flood slide with stain; rinse and dry
  3. Microscopy:
    - place drop of oil on slide; examine with 100x objective lens
87
Q

what are differential stains?

A

stains that render different kinds of cells different colors.

88
Q

what are the two major groups bacteria can be divided into based on their reaction to gram staining?

A
  • gram positive

- gram negative

89
Q

what color do gram positive bacteria appear after staining?

A

purple-violet

90
Q

what color do gram negative bacteria appear after staining?

A

pink

91
Q

why do color differences occur in gram positive/negative bacteria after staining?

A

because of differences in the cell wall structure of the different types of bacteria

92
Q

what is the procedure for gram staining?

A
  1. flood heat fixed smear with crystal violet
  2. add iodine
  3. add alcohol to remove color from gram negative cells.
  4. add safranin to make gram negative cells red
93
Q

why is ethanol used in gram staining?

A

to decolorize gram negative cells but not gram positive cells

94
Q

how can the gram stain be reduced to a one step procedure?

A

fluorescent microscopy because gram positive and gram negative cells can fluoresce different colors when treated with a special chemical

95
Q

what is a common drawback with staining in light microscopy?

A

it often kills cells and can distort their features

96
Q

what are the two forms of light microscopy that improve contrast without staining?

A
  • phase contrast

- dark-field microscopy

97
Q

which microscope in particular is widely used for the observation of living samples?

A

phase-contrast microscope

98
Q

what is the purpose of the phase ring in phase-contrast microscopy

A

the phase ring amplifies the contrast resulting in a dark image on a light background

99
Q

what does the phase ring consist of?

A

a phase plate that amplifies the variation in phase to produce the higher-contrast image

100
Q

instead of light passing through the specimen, what occurs during dark-field microscopy?

A

light is directed from the sides of the specimen and only light that is scattered when it hits the specimen can reach the lens

101
Q

how does the specimen appear in dark-field microscopy?

A

light on a dark background

102
Q

what microorganisms is the dark-field microscope very good at viewing?

A

motile microbes such as flagella

103
Q

the fluorescence microscope visualizes specimens that ________

A

fluoresce

104
Q

t/f all cells viewed in fluorescence microscopy must be naturally fluorescent

A

false, they can be made to fluoresce artificially through using DAPI.

105
Q

what is DAPI? how is it used?

A

a fluorescent dye that stains cells bright blue. it can be used to visualize cells in their natural habitats and is used widely in ecology

106
Q

name the 2 methods of light microscopy that produce 3d images:

A
  • differential interference contrast microscopy

- confocal scanning laser microscopy

107
Q

fun fact: DIC is especially helpful in viewing eukaryotic structures such as the nucleus, or endospores and vacuoles.

A

freebee

108
Q

fun fact: Confocal scanning laser microscopy involves the microscopes laser scanning up and down through the lasers of each sample and using a computer to generate a 3d image of the sample

A

freebee

109
Q

what do electron microscopes use that differs from the visible light in light microscopes?

A

electrons

110
Q

what is a photograph taken by an electron microscope called?

A

electron micrograph

111
Q

what two types of electron microscopy are in routine use in microbiology?

A
  • transmission electron microscopy

- scanning electron microscopy

112
Q

describe the pros and cons of the transmission electron microscope:

A
  • very powerful resolution
  • must use thin slides
  • can view things at the molecular level
113
Q

describe the pros and cons for scanning electron microscopy:

A
  • fairly large specimens can be observed
  • typically only the surface is visualized
  • produced in black and white imagery
114
Q

what is the technique that refers to a collection of practices that allow for the preparation and maintenance of sterile?

A

aseptic technique

115
Q

what are pure cultures?

A

those that contain cells from only a single type of microorganism and are of great value for the study of microorganisms

116
Q

what are enrichment culture techniques?

A

techniques which allow for the isolation from nature of microbes having particular metabolic characteristics.

117
Q

why are enrichment culture techniques important?

A

they facilitate the discovery of diverse microorganisms

118
Q

what did Louis Pasteur discover about optical isomers?

A

microorganisms could distinguish between these optical isomers which were in the crystals he was studying that had different molecular structures that influenced their properties

119
Q

optical isomers led louis pasteur to what discovery?

A

many reactions thought to be chemical were actually catalyzed by specific microoorganisms

120
Q

what is the term for the idea that life arose spontaneously from nonliving materials?

A

spontaneous generation

121
Q

what was the purpose of Pasteur’s swan necked flask?

A

it could let fresh air into the reaction but prevent microorganisms from getting in and putrefying.

122
Q

who introduced aseptic techniques for surgeries?

A

Joseph Lister

123
Q

which diseased did pasteur develop vaccines for?

A

fowl cholera
anthrax
rabies

124
Q

pasteur also helped to solidify what theory?

A

the germ theory of disease

125
Q

how did pasteur’s discoveries aid the food industry?

A

his principles were adapted in milk production where they heat it to preserve it. this is called pasteurization

126
Q

who instituted handwashing?

A

ignaz semmelweis

127
Q

what did Koch’s postulates demonstrate?

A

the cause and effect in an infectious disease

128
Q

what are koch’s 4 postulates?

A
  1. The suspected pathogen must be present in all cases of the disease and absent from healthy animals.
  2. The suspected pathogen must be grown in pure culture.
  3. Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal.
  4. The suspected pathogen must be re-isolated and shown to be the same as the original.
129
Q

what other accomplishments did Robert Koch have?

A
  • discovered and proved the cause of tuberculosis
  • found the cause of cholera
  • developed methods to diagnose infection of tb. (tuberculin skin test)
130
Q

what contribution did Martinus Beijerinck make to microbiology?

A
  • developed the enrichment culture technique

- described the first virus and the basic principles of virology

131
Q

what contribution did sergei winogradsky make to microbiology?

A
  • proposed the concept of chemolithotrophy

- was the first to demonstrate nitrogen fixation

132
Q

what is meant by the term chemolithotrophy?

A

this is the oxidation of inorganic compounds to yield energy

133
Q

who discovered DNA?

A

james watson
francis crick
rosalind franklin

Microbiology (2 decks)

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