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2nd Microbio test stuff > Microbial Growth > Flashcards

Microbial Growth Flashcards

1
Q

Physical requirements for growth

A

pH
Temperature
Osmotic Pressure

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2
Q

Chemical requirements for growth

A

Carbon
Nitrogen
Sulfur
Phosphorus
Oxygen
Trace elements
Organic growth factors

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3
Q

3 primary groups for temperature

A

Psychrophiles (cold dudes)
Mesophiles (normal dudes)
Thermophiles (hot dudes … pause)

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4
Q

Pyschotrophs

A

Grow at 0 degrees celsius
Optimum temp 20-30
Can’t grow past 40
Food spoilage of refrigerated foods

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5
Q

Mesophiles

A

Optimum of 25-40
Very similar temp to us as humans (our body temp)
Live in animals
Most common spoilages and disease organisms

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6
Q

Thermophiles

A

Optimum 50-60
Hyperthermophiles >80

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7
Q

What pH do bacteria grow best in?

A

Between 6.5 and 7.5

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8
Q

What do you use to neutralize and maintain proper pH?

A

Buffers

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9
Q

What causes plasmylosis?

A

high osmotic pressure

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10
Q

What is phosphorus used for?

A

DNA
RNA
ATP

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11
Q

Trace elements facts

A

Usually as enzyme cofactors
Inorganic elements required in small amounts
Iron
Copper
Zinc
Molybdenum

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12
Q

Microbes that require oxygen to live are called?

A

obligate aerobes

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13
Q

True or false: Obligate aerobes are at a disadvantage and if so why?

A

TRUE
Oxygen is poorly soluble in water of their own environment

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14
Q

Facultative anaerobns are?

A

Ability to continue growing withount oxygen
Genus: Clostridium

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15
Q

Half of dry weight of a typical bacteria cell is?

A

Carbon

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16
Q

Chemoheterotrophs get most of their carbon from?

A

The source of their energyW

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17
Q

What’s sulfur used for ?

A

Amino Acids
Thiamine
Biotin
Most bacteria decompose protein for the sulfur source

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18
Q

What are the enzymes that help deal with toxic forms of oxygen produced during cellular respiration?

A

Superoxide dismutase
Catalase
Peroxidase

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19
Q

Aerotolerant Anaerobes are?

A

Fermentative
CANNOT use oxygen for growth
Tolerates oxygen
Contain superoxide dismutase

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20
Q

Microaerophiles

A

Are aerobic
Require oxygen
Only grow in oxygen concentrations lower than those in air
Are sensitive to superoxide radicals and peroxides

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21
Q

Where are biofilms found?

A

Digestive system
Sewage treatment systems
Can clog pipes

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22
Q

Biofilms are involved in __ infections (percentage)

A

70%

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23
Q

How do bacteria in biofilms communicate?

A

Quorum sensing

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24
Q

Culture media definition

A

Nutrients prepared for microbial growth

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25
Q

Sterile means?

A

No living microbes

26
Q

Innoculum definition

A

Introducing microbes into medium

27
Q

What is a culture?

A

Microbes growing in or on a culture medium

28
Q

What is agar used as?

A

Solidifying agent for culture media in petri dishes
slants
deeps

29
Q

Agar is not __ by microbes

A

Metabolized

30
Q

Agar liquifies at __ and solidifies at__

A

100 celsius
40 celsius

31
Q

What are the types of culture media?

A

Chemically defined
Complex media

32
Q

Chemically defined media is?

A

Exact chemical composition is known

33
Q

Complex media is?

A

Extracts of meat, yeast, or plants
chemical composition varies bach to bach

34
Q

Types of complex medias?

A

Nutrient broth
Nutrient agat

35
Q

In complex media; the energy, carbon, nitrogen, and sulfur requirements of the microorganism are provided by ___?

A

Protein

36
Q

Partial digestion does what?

A

Acids or enzymes reduce proteins to peptones (shorter chain amino acids)

37
Q

What is reducing media used for?

A

Cultivation of anaerobic bacteriaW

38
Q

What chemical does reducing media have and what does it do?

A

Sodium thioglycate
This combines with O2 and depletes it

39
Q

What is selective media used for?

A

Used to see one particular microorganism

40
Q

Differential media is to for?

A

Distinguishing colonies of a specific microorganism

41
Q

True or false: Differential and selective medias can be combines

A

TRUE
Mannitol Salt agar
Used to select for halophiles

42
Q

What’s an enrichment culture?

A

Provides nutrients and environmental conditions that favor a particular microbe

43
Q

What is a pure culture?

A

Contains only one species or strain

44
Q

What is a colony?

A

Population of cells arising from a single cell or spore
AKA colony forming unit

45
Q

What method is used to isolate pure cultures?

A

Streak plate method

46
Q

How do bacteria grow? (increase in number)

A

Binary fission

47
Q

Binary fission steps

A

Cell elongates and dna is replicated
Cell wall and plasma membrane constrict
Cross wall froms seperating the DNA
Cells seperatw

48
Q

What is the generation time?

A

When number of cells in each generation is expressed as a power of 2, the exponent tells the number of generations (doublings) that have occured
Time required for cell to divide

49
Q

4 basic phases of growth

A

Lag
Log
Stationary
Death Phase

50
Q

Lag phase

A

Intense activity but no increase in population

51
Q

Log phase

A

Increase in population

52
Q

Stationary phase

A

Period of equilibrium

53
Q

Death phase

A

Population is decreasing

54
Q

What’s an advantage of using the plate count method?

A

It measures the number of viable cellsW
Most common used

55
Q

What’s a disadvantage of plate count method?

A

It takes time , usually 24 hours

56
Q

What do platecounts assume?

A

Assume that each live bacterium grows and divides to produce a single colony
However, this is not always true

57
Q

What can cause innacuracy in plate count?

A

Too many colonies present and cells overcrowd and don’t develop

58
Q

What is the golden rule

A

FDA: 24-250
Scientists: 30-300

59
Q

Serial dilution does what?

A

Dilutes the original inoculum several times to ensure colony is in golden rule range

60
Q

When is most probable number method useful?

A

When microbes won’t grow on solid medium
When growth of bacteria in liquid differential medium is used to id microbes

2nd Microbio test stuff (5 decks)

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