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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
2 broad groups of organisms based on their Carbon source
- autotrophs | - heterotrophs
26
organisms that can use inorganic carbon source (e.g., CO2) as their sole source of carbon
Autotrophs
27
organisms that catabolize reduced organic molecules (e.g., proteins, carbs, amino acids, fatty acids) acquired from other organisms
Heterotrophs
28
2 groups of organisms based their use of chemicals or light as energy source
- chemotrophs | - phototrophs
29
organisms that acquire energy from redox rxns involving inorganic and organic chemicals
Chemotrophs
30
organisms that use light as energy source
Phototrophs
31
4 groups of organisms based on their carbon and energy sources
- photoautotrophs - chemoautotrophs - photoheterotrophs - chemoheterotrophs
32
organisms that use light as energy source and inorganic carbon as its carbon source
Photoautotrophs
33
examples of photoautotrophs
- plants - some protozoans - algae - prokaryotes
34
organisms that use chemicals as energy source and inorganic carbon as its carbon source
Chemoautotrophs
35
example of chemoautotrophs
Prokaryotes
36
organisms that use light as energy source and organic carbon as its carbon source
Photoheterotrophs
37
example of photoheterotrophs
Prokaryotes
38
organisms that use chemicals as energy source and organic carbon as its carbon source
Chemoheterotrophs
39
example of chemoheterotrophs
- animals - fungi - other protozoans - prokaryotes
40
2 groups of organisms based on their hydrogen source
- organotrophs | - lithotrophs
41
organisms that acquire electrons from the same organic molecules that provide them carbon & energy
Organotrophs
42
organisms that acquire electrons from inorganic hydrogen sources, e.g., H2, NO2, H2S, FE2+
Lithotrophs
43
5 groups of organisms based on oxygen requirement
- obligate aerobes - obligate anaerobes - facultative anaerobes - aerotolerant anaerobes - microaerophiles
44
Why is oxygen an essential nutrient for bacteria?
Because it serves as the final electron acceptor of electron transport chains which produce most of the ATP in bacteria
45
True or False | Obligate aerobes can still grow even without oxygen in their environment
False, oxygen must be present
46
examples of obligate aerobes
- algae - most fungi - protozoans - many prokaryotes
47
True or False | Obligate anaerobes cannot grow without oxygen in their environment
False, oxygen must be absent
48
highly reactive O2 forms toxic for obligate anaerobes
- singlet oxygen (1 O2) - superoxide radical (O2-) - peroxide anion (O2 [2-]) - hydroxyl radical (OH-)
49
pigment that protects organisms from lethal oxidations of singlet oxygen, absent in obligate anaerobes
Carotenoid
50
enzyme necessary to prevent lethal accumulation of superoxide, absent in obligate anaerobes
Superoxide dismutase
51
enzyme that breaks down peroxide anion into water and oxygen, absent in obligate anaerobes
Catalase
52
enzyme that breaks down peroxide anion into water and NAD, absent in obligate anaerobes
Peroxidase
53
radical resulting from the incomplete reduction of H2O2 and ionizing radiation
Hydroxyl radical
54
What are facultative anaerobes?
Organisms that can grow with or without oxygen
55
examples of facultative anaerobes
- Escherichia coli - few yeasts - many prokaryotes - many bacterial pathogens
56
organisms that do not use aerobic metabolism but tolerate oxygen by having some of the enzymes that detoxify toxic oxygen forms
Aerotolerant anaerobes
57
examples of aerotolerant anaerobes
- Lactobacilli - few yeasts - many prokaryotes - few protozoans
58
organisms that require oxygen levels of 2-10%
Microaerophiles
59
Where does Helicobacter pylori thrive?
In the stomach
60
What oxygen concentration would damage microaerophiles?
21% concentration of atmospheric O2
61
examples of microaerophiles
- many prokaryotes | - protozoans
62
___% of the dry weight of microbial cells is nitrogen
14%
63
Why is nitrogen also a growth-limiting nutrient?
Because anabolism stops when there is insufficient nitrogen to build proteins and nucleotides
64
Where can cells recycle nitrogen from?
From their amino acids and nucleotides
65
process wherein a few bacteria (e.g., cyanobacteria & Rhizobium) reduce nitrogen gas to ammonia
Nitrogen fixation
66
Why are nitrogen fixing bacteria essential?
They provide usable nitrogen to other organisms
67
other chemical requirements
- phosphorous - sulfur - calcium, copper, iron - manganese - magnesium - trace elements - growth factors
68
essential organic compounds organisms cannot produce, therefore have to be supplied to them
Growth factors
69
growth factors
- B complex vitamins - amino acids - purines & pyrimidines
70
How are growth factors supplied to bacteria in a culture medium?
Through yeast extracts, whole blood, or serum
71
physical requirements for bacterial growth
- temperature - pH - physical effects of water - CO2
72
3 groups of bacteria based on temperature dependence
- psychrophiles/cryophilic | - mesophiles
73
optimum temperature for psychrophiles
15°C
74
temperature range for psychrophile growth
0-20°C
75
examples of psychrophiles
- algae - fungi - bacteria in snow fields, ice, & cold water - bacteria that cause spoilage of food in fridges
76
optimum temperature range for mesophiles
20-40°C
77
What are thermoduric organisms?
Mesophiles that can survive high temperatures for brief periods
78
What group of bacteria based on temperature do bacteria for man belong in?
Mesophiles as they grow best at 37°C
79
optimum temperature range for thermophiles
temperatures above 45°C
80
members of archaea that grow in water above 80°C or above 100°C
Hyperthermophiles
81
bacteria that grows in 113°C and can survive 121°C for an hour
Pyrodictium
82
a measure of the concentration of hydrogen ions in a solution
pH
83
3 groups of bacteria based on pH requirement
- neutrophiles - acidophiles - alkalinophiles
84
optimum pH range for neutrophile growth
6.5 - 7.5
85
examples of neutrophiles
- most bacteria - most protozoans * including pathogens
86
2 types of acidophiles
- obligate acidophiles | - acid tolerant microbes
87
acidophiles that require an acidic pH and die when pH reaches 7
Obligate acidophiles
88
acidophiles that merely survive acid without preferring it
Acid tolerant microbes
89
examples of acidophiles
- other bacteria | - most fungi
90
True or False | Low pH acts as a preservative by preventing any further bacterial growth
True
91
optimum pH for alkalinophiles
11.5
92
examples of alkalinophiles
Vibrio cholerae - goes best outside the body in water at pH 9
93
How can organisms remain metabolically active?
They must be in a moist environment
94
Why is it detrimental for an organism if it loses water?
80% of its cells' cytoplasm is made up of water
95
dissolves enzymes and nutrients and is an important reactant in many metabolic rxns
Water
96
example of an organism that can survive dry conditions
Mycobacterium tuberculosis
97
component in Mycobacterium tuberculosis that aids in retention of water
High lipid and mycolic acid content
98
the pressure exerted on a semi-permeable membrane by a solution containing solutes that cannot cross the membrane
Osmotic pressure
99
What happens when cells are placed in hypotonic solutions?
Cells gain water and swells | - if cell wall is absent, cell bursts
100
What happens when cells are placed in hypertonic solutions?
Cells lose water and shrink (plasmolysis)
101
If there is high external osmotic pressure, the cells are in what kind of solution?
Hypertonic solution
102
If there is low external osmotic pressure, the cells are in what kind of solution?
Hypotonic solution
103
What does halophile mean?
Salt-loving
104
organisms adapted for growth under high osmotic pressure and can grow in 30% salt
Obligate halophiles
105
organisms that do not require high salt concentration but can tolerate it
Facultative halophiles
106
example of facultative halophiles
Staphylococcus aureus
107
the pressure exerted by water in proportion to its depth
Hydrostatic pressure
108
for every additional 10 meters depth, water pressure increases by ___ atmosphere
1
109
organisms that are living in the ocean basins and trenches which are under extreme pressure
Barophiles
110
organisms that would require CO2 to initiate growth
Capnophiles
111
carbon dioxide is usually supplied in ____ concentration
5-10%
112
How is CO2 supplied in the lab?
- CO2 incubator | - candle jar

Microbiology (4 decks)

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