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Microbiology > Microbial Growth > Flashcards

Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

Slime

A

Biofilms have a matrix

of polysaccharides, DNA, and proteins

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2
Q

Quorum sensing

A

Cell-to-cell chemical communication

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3
Q

Microbes in biofilms

A

1000 times more resistant to microbicides.

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4
Q

What percent of bacterial infections involve biofilms?

A

70%

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5
Q

Culture Media

A

Any nutrient material prepared for the growth of microorganisms in the laboratory.

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6
Q

Culture

A

The growth that results

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7
Q

Should culture media be sterile?

A

YES!

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8
Q

Problems with gelatin as a culture media

A

Melts at room temperature (23 C) and microbes use it for food.

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9
Q

Agar

A

Derived from seaweed and is used as a solidifying agent as culture media.

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10
Q

Benefits of Agar

A

Melts at/near boiling point (98-100 C) and resolidifies at (40 C)

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11
Q

Chemically Defined Media

A

The exact chemical composition is known.

EXPENSIVE

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12
Q

Complex Media

A

Most common media in which the chemical composition varies.

CHEAPEST

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13
Q

Selective Media

A

Suppress the growth of unwanted bacteria and promote the growth of desired microbes.

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14
Q

What can be used as a selective media?

A 
Inhibitory chemicals (salt)
Antibiotics
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15
Q

Differential Media

A

Makes it easier to distinguish colonies of desired colonies growing on the same plate.

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16
Q

Alpha hemolysis

A

Causes green discoloration.

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17
Q

Beta hemolysis

A

Completely destroys all the cells.

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18
Q

Gamma hemolysis

A

Nothing happened.

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19
Q

Streptococcus pyogenes

A

Only member of Group A streptococci, causes beta hemolysis and is the causative agent of strep-throat

20
Q

Pyrogenic

A

Creates pus

21
Q

Streptococcus agalactiae

A

Only member of Group B streptococci, causes beta hemolysis and is the causative agent of neonatal sepsis.

22
Q

Fermentation of lactose

A

Used to distinguish some

Intestinal pathogens from nonpathogens.

23
Q

Pathogenic, non-lactose fermenters

A

Salmonella and Shigella

24
Q

E.Coli

A

Ferments lactose to acid products.

25
Q

Some media are ____ selective and differential

A

Both

26
Q

How do we obtain a pure culture?

A

Streak Plate method is the most common.

27
Q

Streak Plate Method

A

(1) Inoculating material with mixed organisms onto quadrant #1.
(2) Using sterile loop, streak some of the material into quadrant #2.
(3) repeat using sterile lol each time tell you have 4 quadrants.

28
Q

Results of a Streak Plate

A

Isolated colonies from only one bacterium (genetically identical), can be transferred to new agar plate for a pure culture.

29
Q

Deep Freezing

A

Happens at (-50 C -95 C)
Good for
Years

30
Q

Freeze-drying (lyophilization)

A

Bacterial culture is frozen and the water is removed by a high vacuum.
Good for years/decades

31
Q 
Generation time
 (doubling time)
A

The time it takes the population of bacteria to double.

32
Q

Escherichia coli

A

20-30 minutes

33
Q

Mycobacterium Tuberculosis

A

1 day

34
Q

Mycobacterium Leprae

A

14 days

35
Q

Rapid doubling time causes symptoms ______.

A

Faster

36
Q

Lag Phase

A

A period of little or no cell growth but INTENSE METABOLISM while the cells adjust to a new environment.

37
Q

Log Phase

(exponential growth phase)

A

Period that the cells are reproducing most actively.

Cellular respiration is most active! Yeah

38
Q

Stationary Phase

A

Growth slows and deaths equal the number of births

  • less nutrients
  • toxic ware
39
Q

Death Phase

A

Number of deaths exceeds the number of births.

-can go to extinction

40
Q

Bacteria in stationary phase are ______ to respond to antibiotics, like penicillin

A

Unlikely, lancing reduces pressure, drains pus, restores blood flow, and returns the remaining bacteria to log phase to be treated with antibiotics.

41
Q

Standard Plate count

A

A way to the determine viable numbers of microbes that are present. COUNTS ONLY LIVING BACTERIA

42
Q

Filtration

A

Estimating bacterial populations when the quantity of bacteria in the sample is very low. ONLY COUNTS LIVING ORGANISMS

43
Q

Direct Microscopic count

A

Using a measured volume of bacteria suspension and a special counting chamber. COUNTS LIVING AND NON-LIVING

44
Q

Direct electronic counting

A

Special machines that count bacteria as they pass through a sensor. COUNTS LIVING AND NON-LIVING

45
Q

Turbidity (cloudiness)

A

The degree of turbidity indicated the population density. Can be measure with photodetector

Microbiology (4 decks)

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