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microbiology ch 6 Flashcards

1
Q

What are three physical factors for microbial growth?

A

Temperature, pH, osmotic pressure

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2
Q

What are 7 chemical factors for microbial growth?

A

Carbon, nitrogen, sulfur, phosphorus, oxygen, trace elements and organic growth factors

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3
Q

Temperature, pH, and osmotic pressure are physical factors for this

A

Microbial growth

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4
Q

Elements like nitrogen, sulfur, phosphorus, oxygen, and carbon, as well as trace elements and organic growth factors, are chemical requirements for this

A

Microbial growth

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5
Q

What is the minimum growth temperature?

A

The lowest temperature at which a species will grow

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6
Q

What is the optimum growth temperature?

A

The temperature at which a species grows best

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7
Q

What is the maximum growth temperature?

A

The highest temperature at which growth is possible

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8
Q

What is the typical range of degrees between minimum and maximum growth temperatures?

A

30 degrees celsius

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9
Q

This is the lowest temperature at which a species will grow

A

Minimum growth temperature

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10
Q

This is the temperature at which a species grows best

A

Optimum growth temperature

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11
Q

This is the highest temperature at which a species will be able to grow

A

Maximum growth temperature

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12
Q

What temperatures do psychrophiles live in?

A

Cold temperatures

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13
Q

What temperatures do mesophiles live in?

A

Moderate temperatures

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14
Q

What temperatures do thermophiles live in?

A

High temperatures

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15
Q

These microbes grow in cold temperatures

A

Psychrophiles

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16
Q

These microbes flourish in moderate temperatures

A

Mesophiles

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17
Q

These microbes thrive in high temperatures

A

Thermophiles

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18
Q

What temperature range do psychotrophs grow in?

A

Between 0 and 20/30 degrees Celsius

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19
Q

These bacteria cause food spoilage

A

Psychrotrophs

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20
Q

These bacteria grow between 0 and 20/30 degrees Celsius

A

Psychrotrophs

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21
Q

What temperature range do mesophiles grow optimally in?

A

25 to 40 degrees Celsius

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22
Q

What temperature type of microbe are the most common?

A

Mesophiles

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23
Q

What is the optimal temperature for most pathogenic bacteria?

A

37 degrees C

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24
Q

This group of microbes contains the most common spoilage and disease organisms

A

Mesophiles

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25
Q

These microbes grow optimally in temperatures of 25 to 40 degrees Celsius

A

Mesophiles

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26
Q

Are mesophiles the most common type of microbe?

A

Yes

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27
Q

Are psychrophiles the most common type of microbe?

A

No

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28
Q

37 degrees is the optimal temperature for this kind of bacteria

A

Pathogenic bacteria

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29
Q

What is the optimum growth temperature range for thermophiles?

A

50 to 60 degrees C

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30
Q

What are two common locations to find thermophiles?

A

Hot springs and organic compost

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31
Q

What is the optimum growth temperature range for hyperthermophiles?

A

> 80 degrees C

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32
Q

What is another name for hyperthermophiles?

A

Extreme thermophiles

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33
Q

Where are two common locations to find hyperthermophiles?

A

Volcanic hot springs and deep-sea hydrothermal vents

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34
Q

These microbes optimally grow between 50 and 60 degrees Celsius

A

Thermophiles

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35
Q

These microbes can be found in hot springs and organic compost

A

Thermophiles

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36
Q

These microbes grow at temperatures above 80 degrees Celsius

A

Hyperthermophiles

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37
Q

These microbes are also called extreme thermophiles

A

Hyperthermophiles

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38
Q

These microbes are found in volcanic hot springs and deep-sea hydrothermal vents

A

Hyperthermophiles

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39
Q

Are hyperthermophiles members of Domain Bacteria?

A

No

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40
Q

What domain do hyperthermophiles belong to?

A

Archaea

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41
Q

What is the optimum pH range for most bacteria?

A

6.5 to 7.5

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42
Q

What is the optimum pH range for molds and yeasts?

A

5 to 6

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43
Q

What type of microbes grow in acidic environments?

A

Acidophiles

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44
Q

What type of microbes grow in basic environments?

A

Alkaliphiles

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45
Q

6.5 to 7.5 is the optimum pH range for these

A

Most bacteria

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46
Q

5 to 6 is the optimum pH range for these two types of microorganisms

A

Molds and yeasts

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47
Q

Acidophiles prefer this type of environment

A

Acidic environments

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48
Q

Alkaliphiles grow in this type of environment

A

Basic environments

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49
Q

Do microorganisms obtain their nutrients in solution from surrounding water?

A

Yes

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50
Q

Do microorganisms require water for growth?

A

Yes

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51
Q

What do extreme/obligate halophiles require for growth?

A

High osmotic pressure (high salt)

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52
Q

Do facultative halophiles require high salt levels?

A

No

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53
Q

Where do microorganisms obtain their nutrients in solution from?

A

Surrounding water

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54
Q

What do microorganisms require for growth?

A

Water

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55
Q

This type of microbe requires high osmotic pressure from high salt concentrations

A

Extreme/obligate halophiles

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56
Q

This type of microbe does not require high salt levels but can tolerate them

A

Facultative halophiles

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57
Q

What can hypertonic environments cause due to high osmotic pressure?

A

Plasmolysis

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58
Q

What is a hypertonic environment?

A

Concentration of solute is higher outside the cell

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59
Q

What type of cell environment can cause plasmolysis?

A

Hypertonic environment

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60
Q

This is an environment in which the concentration of solute outside the cell is higher than inside the cell

A

Hypertonic environment

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61
Q

This element forms the structural backbone of organic molecules

A

Carbon

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62
Q

What do chemoheterotrophs use as energy?

A

Organic molecules

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63
Q

From where do autotrophs derive their carbon?

A

Carbon dioxide

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64
Q

Do chemoheterotrophs use carbon dioxide as a carbon source?

A

No

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65
Q

These derive their carbon from organic molecules

A

Chemoheterotrophs

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66
Q

These derive their carbon from carbon dioxide

A

Autotrophs

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67
Q

This element is essential for the synthesis of proteins, DNA and ATP

A

Nitrogen

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68
Q

What do most bacteria do to get nitrogen?

A

Decompose protein material

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69
Q

What do some bacteria use as a nitrogen source?

A

NH4+ or NO3- from organic material

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70
Q

What do a few bacteria use in nitrogen fixation?

A

N2

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71
Q

What three things is nitrogen essential for?

A

Synthesis of proteins, DNA, and ATP

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72
Q

Why do most bacteria decompose protein material?

A

For a nitrogen source

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73
Q

Do most bacteria use NH4+/NO3- from organic material as a nitrogen source?

A

No

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74
Q

Do a few types of bacteria use N2 in nitrogen fixation?

A

Yes

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75
Q

What is sulfur used for?

A

Synthesis of amino acids that contain sulfur, and in vitamins such as thiamine and biotin

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76
Q

What do most bacteria do for their sulfur source?

A

Decompose protein

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77
Q

What do some bacteria use for a sulfur source?

A

SO4 2- or H2S

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78
Q

What three molecules is phosphorus used to make?

A

DNA, RNA, ATP

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79
Q

Is phosphorus used for the synthesis in phospholipids of cell membranes?

A

Yes

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80
Q

This ion is a source of phosphorus

A

PO4 3-

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81
Q

Certain amino acids as well as vitamins such as thiamine and biotin use this element in their synthesis

A

Sulfur

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82
Q

Do few bacteria decompose protein for their sulfur source?

A

No

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83
Q

Do most bacteria use SO4 2- for their sulfur source?

A

No

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84
Q

This element is used in DNA, RNA, and ATP

A

Phosphorus

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85
Q

This element is used for the synthesis in phospholipids of cell membranes

A

Phosphorus

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86
Q

What are trace elements?

A

Inorganic elements required in small amounts

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87
Q

What are trace elements typically required for?

A

Enzyme cofactors

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88
Q

What are four examples of trace elements?

A

Iron, copper, molybdenum, and zinc

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89
Q

These are inorganic elements required in small amounts

A

Trace elements

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90
Q

These are typically required as enzyme cofactors

A

Trace elements

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91
Q

These include iron, copper, molybdenum, and zinc

A

Trace elements

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92
Q

What do aerobes required for growth?

A

Oxygen

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93
Q

What do microaerophiles require?

A

Oxygen concentration lower than air

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94
Q

What microbes are unable to use oxygen and are often harmed by it?

A

Anaerobes

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95
Q

What are aerotolerant anaerobes?

A

Microbes that can tolerate but not use oxygen

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96
Q

Are obligate anaerobes killed by oxygen?

A

Yes

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97
Q

Do obligate aerobes not require oxygen?

A

No

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98
Q

These grow in the presence of air or require oxygen for growth

A

Aerobes

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99
Q

These microbes require oxygen

A

Obligate aerobes

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100
Q

These microbes grow via fermentation or anaerobic respiration when oxygen is not available

A

Facultative anaerobes/aerobes

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101
Q

These require oxygen concentration lower than air

A

Microaerophiles

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102
Q

These can tolerate but not use oxygen

A

Aerotolerant anaerobes

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103
Q

These are killed by oxygen

A

Obligate anaerobes

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104
Q

What is singlet oxygen?

A

O2-, a normal molecular oxygen boosted to a higher energy state

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105
Q

Is singlet oxygen reactive?

A

Yes

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106
Q

What are four toxic forms of oxygen?

A

Singlet oxygen (O2-), superoxide radicals (O2-), peroxide anion (O2 2-), and hydroxyl radical (OH*)

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107
Q

What enzyme changes O2- to O2?

A

Superoxide dismutase

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108
Q

This is a normal molecular oxygen boosted to a higher energy state and is extremely reactive

A

Singlet oxygen

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109
Q

What is superoxide dismutase?

A

Enzyme that facilitates reaction of O2- to O2

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110
Q

What enzyme changes peroxide anions into less toxic forms?

A

Peroxidase

111
Q

What are organic growth factors?

A

Essential organic compounds an organism is unable to synthesize

112
Q

From where must organic growth factors be obtained?

A

From the environment

113
Q

What are four types of organic growth factors?

A

Vitamins, amino acids, purines, pyrimidines

114
Q

What are essential organic compounds that an organism can’t synthesize?

A

Organic growth factors

115
Q

Can organic growth factors only be obtained from the environment?

A

Yes

116
Q

Vitamins, amino acids, purines, and pyrimidines are examples of these

A

Organic growth factors

117
Q

What is a biofilm?

A

Microbial community comprised of a thin, slimy layer encasing bacteria that adheres to a surface

118
Q

What do biofilms form?

A

Slime or hydrogels

119
Q

What is a hydrogel?

A

Complex polymer containing many times its dry weight in water

120
Q

How do bacteria communicate in a biofilm?

A

Via quorum sensing

121
Q

What do bacteria secrete to attract other bacterial cells?

A

Inducer (signaling chemical)

122
Q

These are microbial communities of bacteria encased in a thin, slimy layer that adheres to a surface

A

Biofilms

123
Q

This is a complex polymer containing many times its dry weight in water

A

Hydrogel

124
Q

What is quorum sensing used for?

A

Bacterial cell-to-cell communication

125
Q

What do bacteria use inducer (signaling chemical) for?

A

Attracting other bacterial cells

126
Q

Do bacteria in biofilms share nutrients?

A

Yes

127
Q

What three things do biofilms shelter bacteria from?

A

Desiccation, antibiotics, and immune system

128
Q

Do biofilms hinder the transfer of genetic information?

A

No

129
Q

These allow bacteria to share nutrients

A

Biofilms

130
Q

These shelter bacteria from harmful environmental factors such as desiccation, antibiotics, and the immune system

A

Biofilms

131
Q

These facilitate the bacterial transfer of genetic information (e.g. conjugation)

A

Biofilms

132
Q

What are two places biofilms can be found?

A

In digestive system and in sewage treatment systems

133
Q

How much more resistant to microbicides do biofilms make bacteria?

A

1000x resistant

134
Q

Are biofilms involved in 30% of infections?

A

No

135
Q

Are biofilms involved in 70% of infections?

A

Yes

136
Q

What are 4 examples of medical equipment inserted into the body that can form biofilms?

A

Catheters, heart valves, contact lenses, dental caries

137
Q

These are found in the digestive system and in sewage treatment systems

A

Biofilms

138
Q

These are 1000x resistant to microbicides

A

Biofilms

139
Q

These are involved in 70% of infections

A

Biofilms

140
Q

Catheters, heart valves, contact lenses, and dental caries can all be colonized by these

A

Biofilms

141
Q

What is a culture medium?

A

Nutrient material prepared for microbial growth in a laboratory

142
Q

What does sterile mean?

A

Containing no living microbes

143
Q

What is inoculum?

A

Microbes introduced into a culture medium to initiate growth

144
Q

What is a culture?

A

Microbes growing in or on a culture medium

145
Q

What is nutrient material prepared for microbial growth in a laboratory?

A

Culture medium

146
Q

What means containing no living microbes?

A

Sterile

147
Q

What is microbes introduced into a culture medium to initiate growth?

A

Inoculum

148
Q

What is microbes growing in or on a culture medium?

A

Culture

149
Q

What is agar?

A

Complex polysaccharide

150
Q

What is agar used for?

A

Solidifying agent for culture media in petri plates, slants and deeps

151
Q

Is agar generally metabolized by microbes?

A

No

152
Q

At what temperature does agar liquefy?

A

100 degrees C

153
Q

At what temperature does agar solidify?

A

-40 degrees C

154
Q

This is a complex polysaccharide that is used as a solidifying agent for culture media

A

Agar

155
Q

What are 6 components of a culture media?

A

Energy source, carbon source, nitrogen source, sulfur source, phosphorus source, and organic growth factors the organism is unable to synthesize

156
Q

What is chemically defined media?

A

Media in which the exact chemical composition is known

157
Q

What are fastidious organisms?

A

Those that require many growth factors provided in chemically defined media

158
Q

Do fastidious organisms have complex/particular growth requirements?

A

Yes

159
Q

What is complex media?

A

Media containing extracts and digests of yeasts, meat, or plants; exact composition varies

160
Q

What are two examples of complex media?

A

Nutrient broth and nutrient agar

161
Q

What type of organisms require chemically defined media?

A

Autotrophs

162
Q

What type of organisms uses complex media?

A

Heterotrophs

163
Q

In this type of culture media, the exact chemical composition is known

A

Chemically defined media

164
Q

These organisms require many growth factors and have complex/particular growth requirements

A

Fastidious organisms

165
Q

This type of culture media varies batch to batch and contains extracts of yeasts/meat/plants

A

Complex media

166
Q

Nutrient broth and nutrient agar are two examples of this type of culture media

A

Complex media

167
Q

Autotrophs require this type of culture media

A

Chemically defined media

168
Q

Heterotrophs require this type of culture media

A

Complex media

169
Q

What is reducing media used for?

A

Cultivation of anaerobic bacteria

170
Q

What does reducing media contain?

A

Chemicals (sodium thioglycolate) that combine O2 to deplete it

171
Q

Is reducing media heated to drive of O2?

A

Yes

172
Q

Is reducing media typically a solid?

A

No

173
Q

This media is used for the cultivation of anaerobic bacteria

A

Reducing media

174
Q

This media contains a chemical (sodium thioglycolate) that combines O2 to deplete it

A

Reducing media

175
Q

This media is typically a broth and is heated to drive off O2

A

Reducing media

176
Q

What are capnophiles?

A

Microbes that require high CO2 conditions

177
Q

Does media used for capnophiles contain high oxygen?

A

No

178
Q

What does capnophile media resemble?

A

Conditions of intestinal tract, respiratory tract, and other body tissues

179
Q

Do capnophile cultures contain a CO2 packet?

A

Yes

180
Q

Do capnophile cultures contain a candle?

A

Yes

181
Q

These microbes require high CO2 conditions and low oxygen

A

Capnophiles

182
Q

Media for this type of microbes resembles the intestinal tract, respiratory tract, and other body tissues

A

Capnophiles

183
Q

This type of culture media contains CO2 packets and candles

A

Capnophile culture media

184
Q

What are the four biosafety levels?

A

BSL-1 through BSL-4

185
Q

What does BSL-1 entail?

A

No special precations

186
Q

What does BSL-2 entail?

A

Lab coat, gloves, eye protection

187
Q

What does BSL-3 entail?

A

Biosafety cabinets to prevent airborne transmission

188
Q

What does BSL-4 entail?

A

Sealed, negative pressure; “hot zone”; exhaust air is filtered twice through HEPA filters

189
Q

This biosafety level is for basic teaching labs

A

BSL-1

190
Q

This biosafety level requires a lab coat, gloves, and eye protection

A

BSL-2

191
Q

This biosafety level requires seals, negative pressure, and HEPA-filtered exhaust air

A

BSL-4

192
Q

This biosafety level is also known as “hot zone”

A

BSL-4

193
Q

This biosafety level requires biosafety cabinets to prevent airborne transmission

A

BSL-3

194
Q

This biosafety level requires no special precautions

A

BSL-1

195
Q

What is selective media?

A

Media that suppresses unwanted microbes, encourages desired microbes

196
Q

Does selective media contain inhibitors to suppress growth?

A

Yes

197
Q

What is differential media?

A

Media that allows different colonies to distinguish on the same plate

198
Q

Can some media be both selective and differential?

A

Yes

199
Q

This type of media suppresses unwanted microbes and encourages desired microbes

A

Selective media

200
Q

This type of media contains inhibitors to suppress growth

A

Selective media

201
Q

This type of media distinguishes colonies of different microbes on the same plate

A

Differential media

202
Q

What is enrichment culture?

A

Culture that encourages the growth of a desired microbe by increasing very small numbers of a desired organism to detectable levels

203
Q

Is enrichment culture usually a liquid?

A

Yes

204
Q

What is enrichment culture usually used to study?

A

Soil and fecal samples

205
Q

This type of culture encourages the growth of a desired microbe by increasing very small numbers of a desired organism to detectable levels

A

Enrichment culture

206
Q

What is a bacterial colony?

A

A population of cells arising from a single cell/spore or from a group of attached cells

207
Q

What is another name for a bacteria colony?

A

Colony-forming unit (CFU)

208
Q

What method is used to isolate pure bacteria cultures?

A

Streak plate method

209
Q

Do clinical samples contain pure cultures?

A

No

210
Q

Do clinical samples contain several different kinds of bacteria?

A

Yes

211
Q

This is a population of cells arising from a single cell or spore or from a group of attached cells

A

Colony

212
Q

Colony-forming unit (CFU) is another name for this

A

Bacterial colony

213
Q

What is the streak plate method used for?

A

To isolate pure cultures

214
Q

What is a good method for short-term but not long-term bacterial culture storage?

A

Refrigeration

215
Q

What is deep-freezing bacterial cultures?

A

Placing pure culture in suspending liquid and quick-freezing at -50 to -95 degrees Celsius

216
Q

What is lyophiliziation?

A

Freeze-drying microbes by quickly freezing at -54 to -72 degrees and dehydrating in a vacuum (sublimation)

217
Q

Is refrigeration good for long-term storage of bacterial cultures?

A

No

218
Q

This is the process of placing microbes in suspending liquid and quick-freezing at extremely cold temperatures

A

Deep-freezing

219
Q

This is the process of quickly freezing then dehydrating microbes in a vacuum

A

Lyophiliziation (freeze-drying)

220
Q

What are four methods of microbe division?

A

Binary fission, budding, conidiospores, filament fragmentation

221
Q

What type of division is typically used by bacteria?

A

Binary fission

222
Q

What is generation time?

A

Time required for a cell to divide

223
Q

What is the range for generation times for different bacteria species?

A

20 minutes to 24 hours

224
Q

How does binary fission increase the number of cells each generation?

A

By 2 raised to the number of generations

225
Q

How are bacterial growth curves represented graphically?

A

Logarithmically

226
Q

This is the time required for a cell to divide

A

Generation time

227
Q

This typically ranges from 20 minutes to 24 hours, depending on species

A

Generation time

228
Q

Does binary fission quadruple the number of cells in each generation?

A

No

229
Q

2 raised to the number of generations gives this

A

Total number of cells

230
Q

Are bacterial growth curves represented arithmetically on graphs?

A

No

231
Q

What is lag phase?

A

Time interval with no growth

232
Q

What is log phase?

A

Period of bacterial growth/logarithmic increase in cell numbers

233
Q

What is log phase also called?

A

Exponential growth phase

234
Q

What is the stationary phase?

A

When the number of cells dividing equals the number of cells dying

235
Q

When does the stationary phase happen?

A

As bacteria approach carrying capacity

236
Q

What is carrying capacity?

A

The maximum number of organisms an environment can support

237
Q

What is the death phase?

A

Period of logarithmic decrease in bacterial populations

238
Q

What is the death phase also called?

A

Logarithmic decline phase

239
Q

This is the time interval with no growth as bacteria are preparing to divide

A

Lag phase

240
Q

This is the period of bacterial growth that results in logarithmic increase; also known as exponential growth phase

A

Log phase

241
Q

This is the growth phase in which the number of cells dividing equals the number dying

A

Stationary phase

242
Q

When bacteria approach carrying capacity, they enter this growth phase

A

Stationary phase

243
Q

This is the maximum number of organisms that an environment can support

A

Carrying capacity

244
Q

This is the period of logarithmic decrease in bacterial populations; also known as logarithmic decline phase

A

Death phase

245
Q

What are four ways to directly measure microbial growth?

A

Plate count; filtration; most probable number (MPN); direct microscopic count

246
Q

What do plate counts measure?

A

The number of colony-forming units on a solid medium

247
Q

How many colonies are preferred to do a plate count?

A

30-300

248
Q

What process must be done with the original inoculum to ensure the right number of colonies are on the plate?

A

Serial dilution

249
Q

What are two methods to inoculate a plate with bacteria for counting?

A

Pour plate method and spread plate method

250
Q

What does the pour plate method involve?

A

Inoculating empty plate with bacteria, then adding melted agar and swirling to mix

251
Q

What does the spread plate method involve?

A

Inoculating a solid medium with bacteria, then spreading it over the surface

252
Q

What is the purpose of serial dilution?

A

To ensure right number of colonies on medium to be counted

253
Q

The pour plate method and spread plate method are two ways to do this

A

Perform plate counts

254
Q

If 54 colonies are on a plate of 1:1000 dilution, what is the bacteria count from the sample?

A

54,000

255
Q

How many mL are taken from each test tube in serial dilution?

A

1

256
Q

Which method of preparing plates for plate counts results in colony growth in and on solidified medium?

A

Pour plate method

257
Q

Does the spread plate method result in colonies growing only on surface of medium?

A

Yes

258
Q

What method of direct microbial growth measurement is used when the quantity of bacteria is very small?

A

Filtration

259
Q

What does filtration to measure microbial growth entail?

A

Passing solution through a filter to collect the bacteria then transferring to a petri dish

260
Q

When is filtration used to measure microbes?

A

When the quantity of bacteria is very small

261
Q

This method of microbial measurement involves passing solutions through a filter, then transferring to a petri dish

A

Filtration method

262
Q

What is involved in direct microscopic count?

A

Placing a volume of bacterial suspension on a microscope slide and calculating the average number of bacteria per viewing field

263
Q

What does direct microscopic count use to count cells?

A

A Petroff-Hausser cell counter

264
Q

In direct microscopic count, what does the number of bacteria per mL equal?

A

The number of cells counted divided by the volume of area counted

265
Q

This method of counting microbes involves placing a volume of bacterial suspension on a defined area of a microscope slide and calculating the average number of bacteria per viewing field

A

Direct microscopic count

266
Q

In direct microscopic count, the number of cells counted divided by the volume of area counted equals this

A

Number of bacteria per milliliter

267
Q

What are three indirect methods to estimate bacterial numbers?

A

Measuring turbidity, metabolic activity, and dry weight

268
Q

How is turbidity measured to estimate bacterial numbers?

A

By measuring cloudiness of a sample with a spectrophotometer

269
Q

How can metabolic activity be used to estimate bacterial numbers?

A

By measuring the amount of metabolic product, which is proportional to the number of bacteria

270
Q

How is dry weight used to estimate bacterial numbers?

A

By filtering, drying, and weighing microbes

271
Q

What type of organisms are measured using the dry weight method?

A

Filamentous organisms

272
Q

This method of bacterial number estimation involves measuring cloudiness with a spectrophotometer

A

Turbidity

273
Q

Is the amount of metabolic product proportional to the number of bacteria in a sample?

A

Yes

274
Q

Is the dry weight method used for non-filamentous organisms?

A

No

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