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Microbiology > Bacterial Growth & Growth Requirements > Flashcards

Bacterial Growth & Growth Requirements Flashcards

1
Q

What does growth in bacteria refer to?

A

Reproduction

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2
Q

How do majority of bacterial cells reproduce?

A

By binary fission

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3
Q

the time it takes for cells to divide and produce a new generation of cells

A

Generation time

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4
Q

the time it takes for cells to double their population size

A

Doubling time

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5
Q

Many bacterial cells have a generation time of _____

A

20 mins

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6
Q

4 phases of bacterial growth

A
  1. lag phase
  2. logarithmic (exponential) phase
  3. stationary phase
  4. death phase
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7
Q

period of adaptation into a new environment or when bacterial cells are placed in a culture medium

A

Lag phase

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8
Q

lag phase is also known as _____

A

Phase of rejuvenescence or physiologic youth

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9
Q

True or False

There is little to no cell division taking place during lag phase, therefore no increase in population size

A

True

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10
Q

Are cells dormant during lag phase? Why or why not?

A

No, they are undergoing intense metabolic activity involving DNA and enzyme synthesis

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11
Q

What happens at the end of lag phase?

A

Cells have usually lost the reserve storage granules

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12
Q

In what phase are cells most active metabolically?

A

Log/logarithmic phase

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13
Q

True or False
There is minimal cell division taking place during log phase, therefore only a slight increase in population size can be observed

A

False, cell reproduction is more active in log phase, hence there is a notable increase in population size

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14
Q

True or False

Young cells during log phase are most susceptible to antimicrobial drugs that interfere with metabolism

A

True

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15
Q

In what phase is the population size stable?

A

Stationary phase

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16
Q

How does the population size remain stable during stationary phase when many cells are dying or already dead?

A

Cell division is still occurring which compensates for dead cells

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17
Q

Does the metabolic activity of surviving cells increase or decrease during stationary phase? Why?

A

Decrease because of the accumulation of waste products that are inhibitory for the cells

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18
Q

How can the stationary phase be postponed?

A

By continually removing the old medium with the waste and some cells using a chemostat and replenishing the medium so cells could still grow

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19
Q

cell division = cell death

In what phase does this equation apply to?

A

Stationary phase

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20
Q

phase wherein many of the cells have died and any cell division occurring can no longer compensate for the dead cells

A

Death/logarithmic decline phase

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21
Q

cell division < cell death

In what phase does this equation apply to?

A

Death/logarithmic decline phase

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22
Q

chemical and energy requirements for bacterial growth

A
  • sources of carbon, energy, & electrons
  • oxygen requirements
  • nitrogen requirements
  • other chemical requirements
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23
Q

a variety of chemicals organisms use for their energy needs and to build organic molecules and cell structures

A

Nutrients

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24
Q

necessary elements in nutrient compounds

A

CHON

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25
Q

2 broad groups of organisms based on their Carbon source

A
  • autotrophs

- heterotrophs

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26
Q

organisms that can use inorganic carbon source (e.g., CO2) as their sole source of carbon

A

Autotrophs

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27
Q

organisms that catabolize reduced organic molecules (e.g., proteins, carbs, amino acids, fatty acids) acquired from other organisms

A

Heterotrophs

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28
Q

2 groups of organisms based their use of chemicals or light as energy source

A
  • chemotrophs

- phototrophs

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29
Q

organisms that acquire energy from redox rxns involving inorganic and organic chemicals

A

Chemotrophs

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30
Q

organisms that use light as energy source

A

Phototrophs

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31
Q

4 groups of organisms based on their carbon and energy sources

A
  • photoautotrophs
  • chemoautotrophs
  • photoheterotrophs
  • chemoheterotrophs
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32
Q

organisms that use light as energy source and inorganic carbon as its carbon source

A

Photoautotrophs

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33
Q

examples of photoautotrophs

A
  • plants
  • some protozoans
  • algae
  • prokaryotes
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34
Q

organisms that use chemicals as energy source and inorganic carbon as its carbon source

A

Chemoautotrophs

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35
Q

example of chemoautotrophs

A

Prokaryotes

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36
Q

organisms that use light as energy source and organic carbon as its carbon source

A

Photoheterotrophs

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37
Q

example of photoheterotrophs

A

Prokaryotes

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38
Q

organisms that use chemicals as energy source and organic carbon as its carbon source

A

Chemoheterotrophs

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39
Q

example of chemoheterotrophs

A
  • animals
  • fungi
  • other protozoans
  • prokaryotes
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40
Q

2 groups of organisms based on their hydrogen source

A
  • organotrophs

- lithotrophs

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41
Q

organisms that acquire electrons from the same organic molecules that provide them carbon & energy

A

Organotrophs

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42
Q

organisms that acquire electrons from inorganic hydrogen sources, e.g., H2, NO2, H2S, FE2+

A

Lithotrophs

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43
Q

5 groups of organisms based on oxygen requirement

A
  • obligate aerobes
  • obligate anaerobes
  • facultative anaerobes
  • aerotolerant anaerobes
  • microaerophiles
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44
Q

Why is oxygen an essential nutrient for bacteria?

A

Because it serves as the final electron acceptor of electron transport chains which produce most of the ATP in bacteria

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45
Q

True or False

Obligate aerobes can still grow even without oxygen in their environment

A

False, oxygen must be present

46
Q

examples of obligate aerobes

A
  • algae
  • most fungi
  • protozoans
  • many prokaryotes
47
Q

True or False

Obligate anaerobes cannot grow without oxygen in their environment

A

False, oxygen must be absent

48
Q

highly reactive O2 forms toxic for obligate anaerobes

A
  • singlet oxygen (1 O2)
  • superoxide radical (O2-)
  • peroxide anion (O2 [2-])
  • hydroxyl radical (OH-)
49
Q

pigment that protects organisms from lethal oxidations of singlet oxygen, absent in obligate anaerobes

A

Carotenoid

50
Q

enzyme necessary to prevent lethal accumulation of superoxide, absent in obligate anaerobes

A

Superoxide dismutase

51
Q

enzyme that breaks down peroxide anion into water and oxygen, absent in obligate anaerobes

A

Catalase

52
Q

enzyme that breaks down peroxide anion into water and NAD, absent in obligate anaerobes

A

Peroxidase

53
Q

radical resulting from the incomplete reduction of H2O2 and ionizing radiation

A

Hydroxyl radical

54
Q

What are facultative anaerobes?

A

Organisms that can grow with or without oxygen

55
Q

examples of facultative anaerobes

A
  • Escherichia coli
  • few yeasts
  • many prokaryotes
  • many bacterial pathogens
56
Q

organisms that do not use aerobic metabolism but tolerate oxygen by having some of the enzymes that detoxify toxic oxygen forms

A

Aerotolerant anaerobes

57
Q

examples of aerotolerant anaerobes

A
  • Lactobacilli
  • few yeasts
  • many prokaryotes
  • few protozoans
58
Q

organisms that require oxygen levels of 2-10%

A

Microaerophiles

59
Q

Where does Helicobacter pylori thrive?

A

In the stomach

60
Q

What oxygen concentration would damage microaerophiles?

A

21% concentration of atmospheric O2

61
Q

examples of microaerophiles

A
  • many prokaryotes

- protozoans

62
Q

___% of the dry weight of microbial cells is nitrogen

A

14%

63
Q

Why is nitrogen also a growth-limiting nutrient?

A

Because anabolism stops when there is insufficient nitrogen to build proteins and nucleotides

64
Q

Where can cells recycle nitrogen from?

A

From their amino acids and nucleotides

65
Q

process wherein a few bacteria (e.g., cyanobacteria & Rhizobium) reduce nitrogen gas to ammonia

A

Nitrogen fixation

66
Q

Why are nitrogen fixing bacteria essential?

A

They provide usable nitrogen to other organisms

67
Q

other chemical requirements

A
  • phosphorous
  • sulfur
  • calcium, copper, iron
  • manganese
  • magnesium
  • trace elements
  • growth factors
68
Q

essential organic compounds organisms cannot produce, therefore have to be supplied to them

A

Growth factors

69
Q

growth factors

A
  • B complex vitamins
  • amino acids
  • purines & pyrimidines
70
Q

How are growth factors supplied to bacteria in a culture medium?

A

Through yeast extracts, whole blood, or serum

71
Q

physical requirements for bacterial growth

A
  • temperature
  • pH
  • physical effects of water
  • CO2
72
Q

3 groups of bacteria based on temperature dependence

A
  • psychrophiles/cryophilic

- mesophiles

73
Q

optimum temperature for psychrophiles

A

15°C

74
Q

temperature range for psychrophile growth

A

0-20°C

75
Q

examples of psychrophiles

A
  • algae
  • fungi
  • bacteria in snow fields, ice, & cold water
  • bacteria that cause spoilage of food in fridges
76
Q

optimum temperature range for mesophiles

A

20-40°C

77
Q

What are thermoduric organisms?

A

Mesophiles that can survive high temperatures for brief periods

78
Q

What group of bacteria based on temperature do bacteria for man belong in?

A

Mesophiles as they grow best at 37°C

79
Q

optimum temperature range for thermophiles

A

temperatures above 45°C

80
Q

members of archaea that grow in water above 80°C or above 100°C

A

Hyperthermophiles

81
Q

bacteria that grows in 113°C and can survive 121°C for an hour

A

Pyrodictium

82
Q

a measure of the concentration of hydrogen ions in a solution

A

pH

83
Q

3 groups of bacteria based on pH requirement

A
  • neutrophiles
  • acidophiles
  • alkalinophiles
84
Q

optimum pH range for neutrophile growth

A

6.5 - 7.5

85
Q

examples of neutrophiles

A
  • most bacteria
  • most protozoans
  • including pathogens
86
Q

2 types of acidophiles

A
  • obligate acidophiles

- acid tolerant microbes

87
Q

acidophiles that require an acidic pH and die when pH reaches 7

A

Obligate acidophiles

88
Q

acidophiles that merely survive acid without preferring it

A

Acid tolerant microbes

89
Q

examples of acidophiles

A
  • other bacteria

- most fungi

90
Q

True or False

Low pH acts as a preservative by preventing any further bacterial growth

A

True

91
Q

optimum pH for alkalinophiles

A

11.5

92
Q

examples of alkalinophiles

A

Vibrio cholerae - goes best outside the body in water at pH 9

93
Q

How can organisms remain metabolically active?

A

They must be in a moist environment

94
Q

Why is it detrimental for an organism if it loses water?

A

80% of its cells’ cytoplasm is made up of water

95
Q

dissolves enzymes and nutrients and is an important reactant in many metabolic rxns

A

Water

96
Q

example of an organism that can survive dry conditions

A

Mycobacterium tuberculosis

97
Q

component in Mycobacterium tuberculosis that aids in retention of water

A

High lipid and mycolic acid content

98
Q

the pressure exerted on a semi-permeable membrane by a solution containing solutes that cannot cross the membrane

A

Osmotic pressure

99
Q

What happens when cells are placed in hypotonic solutions?

A

Cells gain water and swells

- if cell wall is absent, cell bursts

100
Q

What happens when cells are placed in hypertonic solutions?

A

Cells lose water and shrink (plasmolysis)

101
Q

If there is high external osmotic pressure, the cells are in what kind of solution?

A

Hypertonic solution

102
Q

If there is low external osmotic pressure, the cells are in what kind of solution?

A

Hypotonic solution

103
Q

What does halophile mean?

A

Salt-loving

104
Q

organisms adapted for growth under high osmotic pressure and can grow in 30% salt

A

Obligate halophiles

105
Q

organisms that do not require high salt concentration but can tolerate it

A

Facultative halophiles

106
Q

example of facultative halophiles

A

Staphylococcus aureus

107
Q

the pressure exerted by water in proportion to its depth

A

Hydrostatic pressure

108
Q

for every additional 10 meters depth, water pressure increases by ___ atmosphere

A

1

109
Q

organisms that are living in the ocean basins and trenches which are under extreme pressure

A

Barophiles

110
Q

organisms that would require CO2 to initiate growth

A

Capnophiles

111
Q

carbon dioxide is usually supplied in ____ concentration

A

5-10%

112
Q

How is CO2 supplied in the lab?

A
  • CO2 incubator

- candle jar

Microbiology (4 decks)

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