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Microbiology > 6 - Growth > Flashcards

6 - Growth Flashcards

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1
Q

Obligate

A

requires

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2
Q

Facultative

A

doesn’t require, but can have it

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3
Q

Thermophiles

A

heat loving

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4
Q

Mesophiles

A

moderate-temperature loving

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5
Q

Psychrophiles

A

cold loving

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6
Q

Do bacteria do better above or below their optimal temperature?

A

below

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7
Q

What group do most pathogens belong to?

A

Mesophiles

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8
Q

What group are food spoilers that slowly degrade food?

A

psychotrophs

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9
Q

Does refrigeration kill most bacteria?

A

it does not kill most microbes, but does keep them from growing

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10
Q

What pH do most bacteria like?

A

6.5-7.5

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11
Q

What pH do molds/yeasts prefer?

A

5-6

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12
Q

What is a halophile?

A

salt loving

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13
Q

Extreme halophiles

A

grow in high salt concentrations

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14
Q

Obligate halophiles

A

require high salt to grow

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15
Q

Facultative halophiles

A

don’t require but can grow at high salt concentrations

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16
Q

Aerobe

A

use oxygen in energy reactions

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17
Q

Anaerobe

A

do not use oxygen

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18
Q

Aerotolerant anaerobes

A

Can’t use oxygen for growth, but can tolerate it

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19
Q

Microaerophiles

A

require oxygen in small amounts

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20
Q

obligate aerobes

A

require oxygen to live

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21
Q

facultative anaerobes

A

use oxygen but can grow w/o by fermentation or anaerobic respiration

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22
Q

T/F organisms that use oxygen will produce toxic forms of oxygen so it must have enzymes to break down the toxic forms

A

true

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23
Q

What enzymes are responsible for breaking down toxic oxygen?

A
  1. superoxide dismutase (SOD)
  2. catalase
24
Q

What is culture media?

A

nutrient material used to grow microbes in lab (initially sterile)

25
Q

Agar

A

solidified medium polysaccharide from algae (sterile)

26
Q

Inoculum

A

microbes introduced into medium

27
Q

Culture

A

microbes growing in medium

28
Q

What are the six types of media?

A
  1. chemically defined media
  2. complex media
  3. reducing media
  4. selective media
  5. differential media
  6. enrichment media
29
Q

Chemically defined media

A

exact composition is known (so many g of this or that) must contain energy and carbon source for specific microbe

30
Q

Complex media

A

extracts from yeast, meat, plants (exact composition varies from batch to batch) - extracts provide growth factors and vitamins - is the most common

31
Q

Reducing media

A

for anaerobes, have ingredients that combine with and deplete oxygen (tightly capped tubes)

32
Q

Selective media

A

suppress growth of unwanted and encourage growth of desired microbes

33
Q

Differential media

A

can grow everything but some microbes look different than others allowing for distinction of colonies

34
Q

Enrichment media

A

media specific for a microbe, used to increase numbers of an organism - as much bacteria as fast as you can

35
Q

What is a colony?

A

group of multiple cells of the same microbe attached together - that originate from one single cell (all cells in colony are identical)

36
Q

What is the purpose of a streak plate?

A

to get single colonies

37
Q

How do you perform a streak plate

A

sterilize, spread, repeat x4 (sterilize 5x and make sure you draw back through the previous quadrant)

38
Q

How do bacteria cells divide?

A

Reproduction: binary fission

39
Q

Bacteria growth curve stages:

A
  1. lag
  2. log
  3. stationary
40
Q

What happens at the lag stage of the growth curve?

A

beginning of growth

41
Q

What happens at the log stage of the growth curve?

A

cells divide, logarithmic increase

42
Q

What happens at the stationary stage of the growth curve?

A

growth rate slows and reaches equilibriums (death starts from depletion of nutrients, buildup of waste, pH change and more)

43
Q

What happens at the death stage of the growth curve?

A

death exceeds the new cells, logarithmic decrease

44
Q

What are the methods used to count/quantify bacteria?

A
  1. plate counts
  2. MPN
  3. direct microscopic count
  4. Coulter counter
  5. Turbidity
  6. Metabolic activity
  7. Dry weight
45
Q

Plate counts

A

bacteria on plate and count colonies

46
Q

Spread plate method

A

bacteria culture is added on top of solidified agar plate (bacteria grown ON TOP of agar)

47
Q

Pour plate method

A

bacteria in media is added to liquid agar and solidified (bacteria grow WITHIN agar)

48
Q

MPN

A
  • most probable number
  • rough estimate how many bacteria is in the sample
  • good for bacteria that don’t grow on a solid medium
49
Q

Direct microscopic count

A

fast, sample placed on marked slide, physically counts bacteria

50
Q

Coulter counter

A

electronic counters (used in research and hospitals) and counts bacteria for you

51
Q

Turbidity

A

more bacteria in culture = more cloudy or turbid - can be tested with spectrophotometer

52
Q

Metabolic activity

A

measures the amount of waste being made

53
Q

Dry weight

A

filamentous bacteria and fungi can be removed from medium, filtered, dried, and weighed

54
Q

Which organism is killed by atmospheric oxygen?

A

obligate anaerobe

55
Q

How many cells would be present after 4 generations if we started with 3 cell?

A

48

56
Q

Which of the following is NOT a possible reason why exponential growth stops?
a. accumulation of waste products
b. exhaustion of nutrients
c. harmful change in pH
d. all of these are possible reasons

A

D

57
Q

A spectrophotometer can be used to measure

A

turbidity

Microbiology (23 decks)

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