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Fish 154 > Module 4 > Flashcards

Module 4 Flashcards

1
Q

Time required for a bacterial cell to grow
and divide is called?

A

Generation time

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2
Q

Phases of bacterial growth curve includes?

A

lag phase
B: acceleration phase
C: log (exponential) phase
D: deceleration phase
E: stationary phase
F: death phase

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3
Q

The phase with the ff characteristics:
The period of little or no cell division; it can
last for 1 hr to several days. •

Bacteria are becoming “acclimated” to the
new environmental conditions (pH,
temperature, nutrients, etc.)

• Enzymes and intermediates are formed and
accumulate until they are present in
concentrations that are permit growth.

A

Lag phase

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4
Q

What phase is described by the ff
The cells begin to divide and enter a period of
growth or logarithmic increase.

The living bacteria population increase
rapidly with time at an exponential growth in
numbers, and the growth rate increasing with
time.

Cells are most active metabolically thus most
preferred for industrial purposes

Microorganisms are particularly sensitive to
adverse conditions at this phase.

A

Log phase

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5
Q

What phase is described by the ff

The growth rate slows, the number of microbial
deaths balances the number of new cells and
the population stabilizes (equilibrium).

Metabolic activity of individual surviving cell
also slows down.

With the exhaustion of nutrients, accumulation
of metabolic wastes and harmful changes in
pH, the growth rate has slowed to the point
where the growth rate equals the death rate.

Effectively, there is no net growth in the living
bacteria population.

A

Stationary phase

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6
Q

What phase is described by the ff characteristics

The number of deaths eventually exceeds the
number of new cells formed

• The living bacterial population decreases with
time, due to a lack of nutrients and toxic
metabolic by-products.

In many cases (but not always) the bacteria
autolyse (during the death phase) and the
turbidity decreases.

Some species pass through the entire series of
phases in only a few days; others retain some
surviving cells almost indefinitely.

A

Death pase

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7
Q

What kind of direct measuremrnt is described

Most frequently used method of measuring
bacterial population

• An important advantage- it measures the number
of viable cells

• One disadvantage is that it takes some time, usually 24 hrs or more for visible colonies to form

A

Plate counts

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8
Q

Only plates with 25-250 (30-300) are
counted. • To ensure this, the original inoculum is
diluted several times in a process called?

A

Serial dilution

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9
Q

What kind of method is described?

The colonies will grow within the nutrient
agar as well as on the surface of the
agar plate.

• Disadvantages: Heat-sensitive microorganisms may be damaged

Distinctive appearances of colonies are not
achieved

A

Pour plate method

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10
Q

What method positions all the colonies on the surface
and avoids contact of the cells with melted agar?

A

Spread plate method

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11
Q

What method is described by the ff?

This method is used when the quantity of bacteria is very small.

This is frequently
applied to detection and
enumeration of fecal
pollution of food or water.

The colonies formed by
these bacteria are
distinctive when a
differential nutrient medium
is used.

A

Filtration

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12
Q

What type of method is described?

• A statistical estimating technique based on the fact
that the greater the number of bacteria in the sample,
the more dilution needed to reduce the density to the
point at which no bacteria are left to grow in the tubes
in the dilution series

• Useful when microbes will not grow on solid media

• Eg. Coliform bacteria which selectively ferment lactose
to acid

A

Most Probable Number
Method (MPN)

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13
Q

What method us described by the ff?

A measured volume of a bacterial S
suspension is placed within a
defined area on a microscope
slide.

• Motile bacteria are difficult to
count by these methods and
dead are likely to be counted as
live ones.

Main advantage: no incubation
time is required

A

Direct microscopic count

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14
Q

In the driect microscope count, A specially designed slide _ is used.

A

Petroff-Hausser cell counter

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15
Q

What Indirect method is described below:

This method assumes that the amount of certain metabolic
product such as acid or CO2
is in direct proportion to the
number of bacteria present

Ex. Microbiological assay in which acid production is used to
determine amounts

A

Metabolic activity

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16
Q

What Indirect method is described below:

For filamentous microorganisms such as molds, plate count will
not measure increase in filamentous mass.

Fungus is removed from the growth medium, filtered to remove
extraneous material, placed in weighing bottle and dried in a
dessicator

Can be done in bacteria

A

Dry weight

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17
Q

What Indirect method is described?

As bacteria multiply in liquid
medium, the medium becomes
cloudy with cells.

The instrument used to measure
This method is spectrophotometer

A

Turbidity

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18
Q

The change of light will register as
percentage of transmission or
logarithmic expression called?

A

absorbance or optical density (OD)

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19
Q

FACTORS AFFECTING MICROBIAL GROWTH

A
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20
Q

Physical requirements for growth of microbes?

A

temperature, pH and osmotic
pressure

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21
Q

Chemical requirements for growth of microbes?

A

Carbon,
Nitrogen, Sulfur, Phosphorus, Oxygen, trace elements and
organic growth factors

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22
Q

PHYSICAL REQUIREMENTS

A
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23
Q

A major environmental factor controlling
microbial growth?

A

Temperature

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24
Q

What do you call the lowest temperature at which microbes
will grow?

A

Minimum Temperature

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25
Q

Temperature at which microbes growth rate is the fastest?

A

Optimum Temperature

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26
Q

The Temperature above which
growth ceases, or highest temperature at which microbes
will grow?

A

Maximum Temperature

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27
Q

What interactions within proteins becomes weaker as temp
decreases and the shape of proteins changes slightly?

A

Hydrophobic

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28
Q

At
low temp metabolic regulatory mechanisms becomes?

A

Distorted

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29
Q

What is determined by heat stability of an organism’s proteins?

A

Max temp

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30
Q

_ Are heat-sensitive thus growth cannot occur at temp that
denature the cell’s proteins?

A

Proteins

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31
Q

What has exceptionally heat-stable proteins?

A

Thermophiles

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32
Q

Grow in a temperature of (0-20C)
• Cold temperature optima
• Most extreme representatives inhabit permanently cold environments

This organism is called?

A

Psychrophiles

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33
Q

It grows in a temperature between (20 – 45C)
• Midrange temperature optima
• Found in warm-blooded animals and in terrestrial and aquatic
environments in temperate and tropical latitudes

This organism is known as?

A

Mesophiles

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34
Q

Organisms grow at temperature between (50- 80C)
• Growth temperature optima between 45ºC and 80ºC

This organism is refer to as?

A

Thermophiles

35
Q

Optima greater than 80°C
• These organisms inhabit hot environments including boiling hot
springs, as well as undersea hydrothermal vents that can have
temperatures in excess of 100ºC

This organisms are referred to as?

A

Hyperthermophiles

36
Q

Most organisms grow best between a pH of?

A

6 and 7.5

37
Q

The internal pH of a cell must stay relatively close to _ even though the external pH is highly acidic or basic?

A

Neutral

38
Q

What do you call the organisms that grow
best at low pH?
Example: (Helicobacter pylori, Thiobacillus thiooxidans )

A

Acidophiles

39
Q

What do you call the organisms that grow
best at high pH
Example: (Vibrio cholera)

A

Alkaliphiles

40
Q

Most of pathogenic bacteria are?

A

Neutrophiles

41
Q

Cell membranes are _ so water
enters or leaves a cell depending on the relative osmotic pressure or concentration of dissolved solutes in the cells
and its environment?

A

highly permeable to water

42
Q

Bacteria maintain a _ because the osmotic pressure of their cell content is greater than the osmotic pressure of the environment

A

positive turgor pressure

43
Q

If the concentration of solutes in the external environment increases, the bacterium pumps
potassium ions [K+] and/or osmoprotectants such as the
_ into the cell and synthesizes the
_

A

amino acid proline

disaccharide trehalose

44
Q

These solutes maintain a _ inside
the cell than the outside

A

higher osmotic pressure

45
Q

The increase in internal osmotic pressure damages _ and interferes with the _

A

essential enzymes

cells metabolism

46
Q

What increases osmotic pressure outside the cell, prevents microbial growth?

A

Adding sugar or salt

47
Q

What do you call it whenorganism can withstand high salt
concentration?

A

Halophiles

48
Q

What do you call organisms that require high
levels of salts for growth?

A

Extreme halophiles

49
Q

What do you call it organisms can tolerate some
reduction in the water activity of their
environment but generally grow best
in the absence of the added solute?

A

Halotolerant

50
Q

What do you call it when organism are able to grow in very
dry environments?

A

Xerophiles

51
Q

Structural backbone of living matter
• Needed for all the organic compounds to that make up
a living cell
• Half the dry weight of a typical bacterial cell

What chemical element is this?

A

Carbon

52
Q

These elements are needed by microorganisms for synthesis of cellular
materials. These elements are?

A

Nitrogen, Sulfur and Phosphorus

53
Q

What elements are also required by microorganisms and often needs as cofactors for
enzymes?

A

Potassium (K), Magnesium (Mg) and Calcium (Ca)

54
Q

Microbes require very small amounts of other mineral elements
such as?

A

Iron (Fe), Copper (Cu), Molybdenum (Mo) and Zinc (Zn) -
trace elements

55
Q

Organic compounds, required in very
small amount and only by some cells. These are referred to as?

A

Growth factors

56
Q

Need very little amount but
critical to cell function.
• Often used as enzyme cofactors

These referred to as?

A

Micronutrients

57
Q

contains a
reducing agent and provides
aerobic and anaerobic
conditions
a) Aerobic
b) Anaerobic
c) Facultative
d) Microaerophile
e) Aerotolerant

A

Thioglycolate broth

58
Q

Toxic forms of oxygen are?

A

Singlet oxygen: O2 boosted to a higher-energy
state
• Superoxide free radicals: O2
–
• Peroxide anion: O2
2–
• Hydroxyl radical

59
Q

A nutrient material prepared for the growth of microorganisms in a laboratory is called?

A

Culture Media

60
Q

When microbes are introduced into a culture medium to initiate growth it is called ?

A

inoculum

61
Q

The microbes that grow and multiply in or on a culture medium is called ?

A

culture

62
Q

What do you call a culture media when exact
chemical composition is known?
• Ex. For a chemoheterotroph,
medium must contain organic
growth factors that serve as a
source of C and energy

A

Chemically defined

63
Q

This culture media is made up of
nutrients such as extracts from yeasts,
meat or plants or digests of proteins
from these or other sources.
• Exact chemical composition varies
from batch to batch.
• Energy, C, N and S requirements
are provided by proteins

A

Complex media

64
Q

Shorter chains of amino
acids from partially digested
proteins is called?

A

Peptones

65
Q

What media must be use when anaerobes might be
killed by exposure to oxygen?

A

Reducing media

66
Q

What media is use to suppress unwanted microbes and
encourage desired microbes?
• Contains one or more agents that
inhibit the growth of a certain
microbe and thereby encourages, or
selects, a specific microbe.

A

Selective media

67
Q

What culture media is referred in the ff?
Suppress unwanted microbes and encourage desired
microbes.

• Is used to encourage the growth of a particular microorganism in a mixed culture

A

Enrichment media

68
Q

What temperature is needed in preserving bacteria culture?

A

Deep-freezing: –50°to –95°C
• Lyophilization (freeze-drying): Frozen (–54° to –72°C) and
dehydrated in a vacuum

69
Q

These tests are designed to detect
the change in pH which would occur if fermentation of
the given carbohydrate occurred

A

Carbohydrate Utilization

70
Q

Acids lower the pH of the medium which will cause the
pH indicator (phenol red) to turn

A

Yellow

71
Q

What test is used to detect the enzyme
amylase, which breaks down starch?

A

Starch hydrolysis

72
Q

The hydrolysis of protein is termed
_ and the enzyme involved is
called a _ .

A

proteolysis

protease

73
Q

This media is used to test if bacteria can
digest the protein gelatin.

A

Gelatin utilization

74
Q

To digest
gelatin, the bacteria must make an enzyme called ? .

A

gelatinase

75
Q

Indole: Break down the amino acid Tryptophan
• Methyl Red: Glucose oxidation
• Voges-Proskauer: Production of neutral end
products
• Citrate: Citrate fermentation
• Used to differentiate the Enterobacteriaceae

A

Imvic test

76
Q

This test is done to determine if bacteria
can breakdown the amino acid
tryptophan into indole.

A

Indole production

77
Q

What is used to determine if glucose can be converted to acidic
products like lactate, acetate, and formate.

A

Methyl red

78
Q

What is used
to determine if glucose can be converted to acetoin (neutral end
products).

A

Vogues Proskauer

79
Q

In this test Growth usually results in the bromothymol
blue indicator, turning from green to blue.
The bromothymol blue pH indicator is a deep
forest green at neutral pH. With an increase
in medium pH to above 7.6, bromothymol
blue changes to blue.

A

Citrate utilization

80
Q

This test determines whether the
microbe reduces sulfur-
containing
compounds to sulfides during
the process of metabolism.

Positive: black

A

Hydrogen Sulfide (H2S) production

81
Q

This test is used to detect the
enzyme urease, which breaks
down urea into ammonia

Postive : pink
Negative: yellow

A

Urea

82
Q

Test is used where enzyme is responsible for protecting
bacteria from hydrogen peroxide (H2O2
)
accumulation, which can occur during
aerobic metabolism.

Positive bubbles

A

Catalase activity

83
Q

This test can be used to check for the
ability of bacteria to migrate away
from a line of inoculation (presence of
flagella).

Positive: migration

A

Non biochemical: Motility test

Fish 154 (6 decks)

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