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Microbiology > Microbiology Notes 21 > Flashcards

Microbiology Notes 21 Flashcards

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Biology 101 flashcards
1
Q

Gas requirements of microorganisms

A

The atmospheric gases that most influence the growth of microorganisms are oxygen (O2) and carbon dioxide (CO2)
Oxygen concentration in air is about 20%
CO2 concentration is about 0.003% (3,000 ppm)

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2
Q

Which atmospheric gases influence the growth of microorganisms the most?

A

oxygen (O2) and carbon dioxide (CO2)

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3
Q

What is the concentration of oxygen in the air?

A

about 20%

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4
Q

What is the concentration of CO2 in the air?

A

about 0.003% (3,000 ppm)

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5
Q

How do capnophiles grow better?

A

grow better at 3-10% concentrations of CO2

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6
Q

Name 3 capnophiles

A

Neisseria, Brucella and Streptococcus pneumonia

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7
Q

What is oxygen essential for?

A

LIFE

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8
Q

What is a powerful oxidizing agent that exists in many toxic forms for life?

A

Oxygen

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9
Q

Microorganisms can be:

A

Oxygen users- aerobes
Oxygen detoxifiers
Non-oxygen users or detoxifiers- anaerobes
Non-oxygen users but detoxifiers

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10
Q

Dangerous metabolic products of O2 include:

A

1O2 singlet oxygen (extremely reactive molecule produced by both living and non-living processes)
-O2 superoxide ion
H2O2 peroxide molecule
OH- hydroxyl radicals

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11
Q

Which bacteria mostly have enzymes to neutralize O2 by-products?

A

Aerobic

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12
Q

Aerobic Bacteria

Superoxide dismutase catalyzes which reaction?

A

-O2 + -O2 + 2H + ==> H2O2 + O2

-O2 from phagocytes

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13
Q

Aerobic Bacteria

Catalase catalyzes which reaction?

A

H2O2 + H2O2 ==> 2H2O + O2

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14
Q

Most bacteria, fungi, algae and protozoa are: aerobes or anaerobes?

A

Aerobes

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15
Q

Which type of bacteria lack superoxide dismutase and catalase to process deleterious forms of oxygen?

A

Anaerobes

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16
Q

Which type of bacteria can not deal with the presence of oxygen and die due to its toxicity?

A

Anaerobic

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17
Q

Growing which type of bacteria usually requires special media, methods of incubation, and handling chambers that exclude oxygen?

A

Anaerobic bacteria

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18
Q

Which bacteria live in deep mud, bottom of oceans, deep soil, and inside animal bodies?

A

Anaerobic

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19
Q

Which bacteria’s metabolism does not require O2 for growth and is not affected by its presence?

A

Faculative anaerobic bacteria

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20
Q

Which type of bacteria can adopt an anaerobic mode of metabolism (fermentation) or opt for aerobic respiration?

A

Faculative anaerobic bacteria

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21
Q

Which bacteria have both superoxide dismutase and catalase enzymes?

A

Faculative anaerobic bacteria (and aerobic bacteria)

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22
Q

Which bacteria do not utilize oxygen but can tolerate its presence?

A

Aerotolerant anaerobes

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23
Q

Which bacteria possess alternate mechanisms for the breaking down of peroxide and superoxide?

A

Aerotolerant anaerobes

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24
Q

Certain lactobacilli and streptococci use manganese ions or peroxidases instead, to perform the task of breaking down peroxide or superoxide.

A

Aerotolerant anaerobes

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25
Q

Which bacteria require only a very small amount of oxygen for growth?

A

Microaerophilic

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26
Q

Which type of bacteria is Treponema pallidum?

A

Microaerophillic

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27
Q

What is Treponema pallidum?

A

The causative agent of syphilis

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28
Q

Where are microaerophilic bacteria found?

A

In soil, water and some human bacterial microflora

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29
Q

The majority of microorganisms live or grow in habitats with a pH of?

A

between 6 and 8

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30
Q

Why do the majority of microorganisms live or grow in habitats with a pH between 6 and 8?

A

because strong acids and bases can be highly damaging to enzymes and other cellular substances

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31
Q

In what pH do human pathogens grow in?

A

6.5-7.5

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32
Q

What pH does Euglena mutabilis (algae) tolerate?

A

0-1 (acidophil)

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33
Q

What pH does Thermoplasma (an archaea bacterum with no cell wall) tolerate?

A

1-2 (lyses at 7)

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34
Q

What can molds and yeasts (fungi) spoil?

A

pickled foods

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35
Q

What are molds and yeasts?

A

Acidophiles

36
Q

Acidophiles

A

A few species of algae and bacteria can actually survive at a pH near that of concentrated hydrochloric acid.

37
Q

What are alkalinophiles?

A

bacteria found in soils with high concentrations of ammonia (NH4)

38
Q

Alkalinophiles

A

Metabolism of urea is one way that Proteus spp. can neutralize the acidity of the urine to colonize and infect the urinary system.

39
Q

Most microbes exist under what kind of osmotic pressure?

A

hypotonic or isotonic conditions

40
Q

Which microorganisms are resistant to high-salt environments?

A

Osmophilic microorganisms

41
Q

Halophiles

A

Halobacterium, Halococcus (10-25% NaCl)

42
Q

What bacteria resists or grows in high salt concentration but can also live in a non-salty environment? Staphylococcus aureus (0.1-20% NaCl)

A

Faculative halophiles

43
Q

Which bacteria stand high hydrostatic pressures (bottom of oceans up to 1000x atm)? These bacteria are so adapted to high pressures that they will rupture or lyse when exposed to normal atmospheric pressure.

A

Barophiles

44
Q

Microbial interactions

A

Microorganisms coexist in varied relationships in nature.

45
Q

Reciprocal, obligatory and beneficial relationship between two organisms.

A

Symbiotic interactions

Mutualism

46
Q

An organism receiving benefits from another without harming the other organism in the relationship.
“Making a living” as intestinal normal flora
Could become a parasite or cause disease
Lactobacillus protects vagina against infections due to
low pH
Staphylococcus epidermis lives on human skin
Many thrive in mouth and large intestine

A

Symbiotic interactions

Commensalism

47
Q

Lactobacillus is involved in which type of symbiotic interaction?

A

Commensalism

48
Q

What does Lactobacillus help with?

A

Protects the vagina against infections due to low pH

49
Q

Where does staphylococcus epidermis live?

A

On human skin

50
Q

Staphylococcus epidermis is involved in which type of symbiotic interaction?

A

Commensalism

51
Q

Name the 3 Symbiotic interactions

A
  1. Mutualism
  2. Commensalism
  3. Parasitism
52
Q

Occurs between a host and an infectious agent; the host is harmed in the interaction

A

Symbiotic interaction

Parasitism

53
Q

A mutually beneficial but not obligatory coexistence in which organisms cooperate to produce a reaction

A

Non-symbiotic interaction

Synergism

54
Q

Entails competition, inhibition, and injury directed against the opposing organism

A

Non-symbiotic interaction

Antagonism

55
Q

Antibiotic production is a special case of which non-symbiotic interaction?

A

Antagonism

56
Q

An interactioin among members of a biofilm that results in a coordinated reaction, such as secretion of inducer molecules
By behaving as a unit, the biofilm remains stable and organized
It can occupy and exploit a wide variety of habitats

A

Quorum sensing

57
Q

Microbial growth

Steps of the binary or transversal fission in bacteria

A

Cell enlarges
Duplication of chromosomes
Formation of central transverse septum
Septum breaks into two daughter cells

58
Q

Time needed for a bacterial population to double in number

A

Generation time (GT)

59
Q

The length of the __ is a measure of the growth rate of an organism

A

Generation time (GT)

60
Q

Compared to other living organisms, bacteria are notoriously rapid

A

Generation time (GT)

61
Q

Population doubles by a factor of

A

two (binary) 2,4,8,16,32,64 and so on

62
Q

Generation time

2^n; what is n?

A

n is the number of generations

63
Q

Bacterial population growth is…

A

geometric or exponential

64
Q

Bacterial populations can grow at a constant rate if all conditions are…

A

favorable

65
Q

Microbial populations grow slor or fast according to…

A

species

66
Q

The average generation time (GT) is…

A

30-60 min under optimum conditions, and longer GT require even days

67
Q

Mycobacterium leprae generation time (GT)

A

10-30 days/gen

68
Q

Salmonella enteritidis generation time (GT)

A

20-30 min/gen

69
Q

Staphylococcus aureus generation time (GT)

A

20-30 min/gen

70
Q

Growth curve of a bacterial culture

A 
Lag phase
Log phase
Stationary phase
Death phase
(relative rates of these events change as the curve proceeds)
71
Q

Lag phase

A

few or no cells

72
Q

Log phase

A

exponential; most cells are alive

73
Q

Stationary phase

A

decrease growth

74
Q

Death phase

A

curve dips downwards

75
Q

If the GT of a bacterial species is 20 min then each cell in the total population will reproduce every 20 min in its ___ phase.

A

log

76
Q

In a few hours, a population of bacteria can easily grow from a small number of cells to several _________

A

million

77
Q

Large bacteria growth numbers

A

a population may rise from 1,000 in 30 min to 1,000,000,000 in 16 hours

78
Q

Logarithmic (log) numbers

A

are used to express bacterial populations in a shorter form
9,658,780 is transformed to a logarithmic form as: log10 9,658,780=6.73
10^6.73 is equal to 9,658,780

79
Q

Enumeration of microorganisms

Cell numbers can be counted directly by

A

Microscopic counting chamber
Coulter chamber
Flow cytometer
Other new methods

80
Q

Cell growth can be determined by

A

turbidometry and a total cell count

81
Q

Practical importance of the growth curve

A

Populations grow slow or fast
Microbes in log phase are more sensitive to changes in the environment
Microbes in log phase are more numerous and virulent than those released later
An infected person sheds more bacteria in early and middle stages of infection
Faster multiplication rate may overwhelm the slower growth rate of the host’s cellular defenses
Do not culture cells beyond stationary phase
Stain young cultures not old ones
Heat and disinfectants increase death rates

82
Q

Calculations

A

Size of population over time: Nf=Ni(2^n)
Ni = initial number of bacteria
Nf = final number of bacteria
n = number of generations
2^n = number of bacteria in the generation
Solve for n: Log Nf = log Ni + nlog2 Where n= Log Nf-logNi/log2
refer to pg 7 notes 21 for example

83
Q

One million bacteria are enough to…

A

spoil food (approximately equivalent to a population derived from 20 generations) look at example on pg 8 notes 21

84
Q

When bacterium grows in a culture medium its log phase is

A

relatively short

85
Q

A bacteriums log phase is limited by

A

nutrient depletion, oxygen depravation, accumulation of inhibitory products, etc.

Microbiology (2 decks)

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