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Microbiology Lab > Lab Exam 2 > Flashcards

Lab Exam 2 Flashcards

1
Q

what is a culture?

A

growing bacteria in a lab setting

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2
Q

what is an inoculum?

A

placing bacteria in a growth medium

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3
Q

why do we use aseptic technique in lab?

A

prevent the spread and contamination of various microbes

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4
Q

what is the difference between a broth and an agar?

A

broth is liquid growth media
agar is solid growth media

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5
Q

what are the types of agar we used in class?

A

within a test tube: angled (slant)
in a petri dish: (plate)

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6
Q

what were the two tools that we have used to inoculate new cultures?

A

loop
cotton swab

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7
Q

what does the abbreviation TSA & TSB stand for?

A

TSA: Tryptic soy agar
TSB: Tryptic soy broth

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8
Q

what is the difference between a defined and a complex media?

A

defined: exact chemical composition is known
complex: exact chemical composition varies and is unknown

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9
Q

Give some examples of what can be used as nutrients in a complex medium.

A

amino acids
glucose
vitamins
nitrogen

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10
Q

Is our standard media for our lab complex or defined?

A

complex

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11
Q

what have been the 3 plating techniques introduced in lab?

A

Streak
Lawn
Zag

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12
Q

what are the steps for streak plate?

A
  1. spread one loopful of bacteria on 1/4 of plate
  2. flame loop
  3. start in zone 1 and spread bacteria over 1/4 of plate
  4. flame loop
  5. start in zone 2 and spread bacteria over 1/4 of plate
  6. flame loop
  7. start in zone 3 and spread bacteria over 1/4 of plate, avoiding zone 1 & 2
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13
Q

what are the steps for lawn plate?

A

take cotton swab of bacteria and cover entire plate, leaving no gaps

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14
Q

what are the steps for zag plate?

A

use loop to swab left and right in a few zig-zags

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15
Q

which of the plating techniques is used to produce pure, isolated colonies from a mixed sample?

A

streak plate

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16
Q

why do we flame the loop between each zone when making a streak plate?

A

to reduce number of microbes as we progress each step

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17
Q

what bacteria did we use for bacterial tranformation?

A

Escherichia coli

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18
Q

what genes are found on the pGLO plasmid? what do they code for?

A

bla gene: allows resistance to ampicillin
araC gene: blocks GFP gene from being able to express (glow) all the time
GFP gene: codes for fluorescence

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19
Q

which gene, when expressed, allows the colonies to glow? what does it stand for? come from?

A

GFP gene
green fluorescence protein
jellyfish

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20
Q

what is required in media in order for colonies to glow?

A

arabinose in the plate allows GFP gene to be expressed (glow) by blocking the araC gene from blocking GFP gene

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21
Q

what is the purpose of LB in the plates?

A

to provide microbes with nutrients

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22
Q

what inoculated plates or side of plates showed transformation? why?

A

LB/amp (+pGLO side) - because growth was present due to bla gene being present within the plasmid
LB/amp/arabinose plate - because growth was present and it fluoresced

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23
Q

what plate shows GFP expression?

A

LB/amp/arabinose plate

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24
Q

In the LB/amp plate, what side (+ or -) should show growth?

A

the positive side

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25
Q

what is the name of the antibiotic resistance gene? what antibiotic is it resistant towards?

A

bla gene - resistant to ampicillin

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26
Q

Gram + or gram - : Bacillus subtilis?

A

gram +

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27
Q

Gram + or gram - : Escherichia coli?

A

gram -

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28
Q

Gram + or gram - : Staphylococcus aureus?

A

gram +

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29
Q

Gram + or gram - : Mycobacterium smegmatis?

A

acid-fast gram +

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30
Q

Gram + or gram - : Pseudomonas aeruginosa?

A

gram -

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31
Q

how did we apply our microbes in the temperature experiment?

A

lawn plate - use cotton swab with bacteria to cover entire plate, leaving no gaps

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32
Q

what were all the temperatures used in the temperature experiment?

A

4
25
37
42
47
60

33
Q

Which temperature in °C is room temperature?

A

25 °C

34
Q

Which temperature in °C is body temperature?

A

37 °C

35
Q

What temperatures in °C is refrigerator temperature?

A

4 °C

36
Q

Know how to convert temperatures.

A

°F = (°C x 1.8) + 32

37
Q

What temperature did all species grow best at?

A

37 °C

38
Q

What genus did not grow well at room temperature?

A

Mycobacterium

39
Q

Why didn’t the bacteria grow at refrigerator temperature?

A

the bacteria underwent bacteriostasis in the cold temperature. Bacteriostasis being the slowing of microbial growth

40
Q

what organisms were used in the antiseptic experiment?

A

Escherichia coli
Pseudomonas aeruginosa
Bacillus subtilis
Staphylococcus aureus
Mycobacterium smegmatis

41
Q

How did we apply our microorganism to the surface of the antiseptic experiment?

A

Lawn plate: take cotton swab with bacteria and cover entire plate, leaving no gaps

42
Q

What were the chemicals used in antiseptic experiment? what is its general chemical type?

A

Iodine – halogen
3% Hydrogen peroxide - Peroxygens
2% chlorhexidine - Biguanides
70% isopropyl alcohol – alcohol
1% formaldehyde - Aldehydes
1% silver nitrate - metal

43
Q

How did we evaluate whether the antiseptic was effective or not?

A

an antiseptic was effective when its death zone was large
an antiseptic was not effective when its death zone was small/nonexistent

44
Q

Which organisms were the most and least resistant in the antiseptic experiement?

A

Most resistant – Escherichia coli
Lest resistant – Mycobacterium smegmatis

45
Q

which chemicals were most and least effective in the antiseptic experiment?

A

Most effective – 1% formaldehyde (largest death numbers)
Least effective – 70% isopropyl alcohol

46
Q

Which organisms were used in the antibiotic/antimicrobial experiment?

A

Escherichia coli
Pseudomonas aeruginosa
Bacillus subtilis
Staphylococcus aureus
Mycobacterium smegmatis

47
Q

How did we apply our microorganism to the antibiotic/antimicrobial experiment?

A

Lawn plate: take cotton swab with bacteria and cover entire plate, leaving no gaps

48
Q

What were the six antibiotics used for this lab exercise? their mode of action?

A

Ciprofloxacin – DNA synthesis inhibitors
Chloramphenicol - protein synthesis inhibitor
Gentamicin - protein synthesis inhibitor
Penicillin - cell wall synthesis inhibitor
Colistin - cell wall synthesis inhibitor
Bacitracin - cell wall synthesis inhibitor

49
Q

How did we evaluate whether the antibiotic was effective or not?

A

Larger death zone meant the antibiotic was effective
Small death zone meant the antibiotic was ineffective

50
Q

Which term is used to describe when a bacterium is easily killed by a particular antibiotic?

A

susceptible

51
Q

what is narrow spectrum?

A

targets a single microbe group

52
Q

what is broad spectrum?

A

inhibits/kills multiple types of organisms

53
Q

Which three antibiotics did not kill a few of the bacteria used in the experiment? How do we know that it did not kill? Does this antibiotic selectively kill Gram + bacteria or Gram - bacteria?

A

Penicillin did not kill Pseudomonas aeruginosa or Mycobacterium smegmatis because there was no death zone present. Penicillin is narrow spectrum for Gram + (does not target gram -)
Colistin did not kill Bacillus subtilis or Staphylococcus aureus because there was no death zone present. Colistin is narrow spectrum for Gram - (does not target gram +)
Bacitracin did not kill Escherichia coli nor Pseudomonas aeruginosa because there was no death zone present. Bacitracin is narrow spectrum for Gram + (does not target gram -)

54
Q

Which organisms were most and least resistant in the antibiotic experiment?

A

Most resistant: Escherichia coli
Least resistant: Mycobacterium smegmatis

55
Q

Which antibiotics were most and least effective in the antibiotic experiment?

A

Most effective: Chloramphenicol
Least effective: Bacitracin

56
Q

What is the definition of a selective media?

A

Inhibits growth of unwanted organisms (only the selected microbes live)

57
Q

What is the definition of a differential media?

A

Allows organisms to grow but the added chemicals make them look different (they change different colors and/or precipitate is visible)

58
Q

What were the three specific plates that we used in our lab? what do the acronyms stand for? what is their original color before inoculation?

A

(MSA) Mannitol Salt Agar (red)
(EMB) Eosin Methylene Blue (dark purple)
(MAC) MacConkey Agar (raspberry)

59
Q

Which plate used in lab this semester is not selective or differential?

A

TSA

60
Q

Which organisms used in selective/differential experiment are Gram + ?

A

Staphylococcus aureus
Staphylococcus epidermidis

61
Q

Which organisms used in selective/differential experiment are Gram - ?

A

Escherichia coli
Enterobacter aerogenes
Proteus vulgaris

62
Q

how is MSA selective?

A

selects for gram +
selects against gram -

63
Q

how is EMB selective?

A

selects for gram -
selects against gram +

64
Q

how is MAC selective?

A

selects for gram -
selects against gram +

65
Q

how is MSA differential?

A

differential for mannitol fermentation

66
Q

how is EMB differential?

A

differential for lactose fermentation

67
Q

how is MAC differential?

A

differential for lactose fermentation

68
Q

what type of fermenter and what are the color possibilities for MSA? what genes and species would be responsible for each?

A

fermenter: turns yellow (Staphylococcus aureus)
nonfermenter remains red (Staphylococcus epidermidis

69
Q

what type of fermenter and what are the color possibilities for EMB? what genes and species would be responsible for each?

A

strong fermenter: turns shiny metallic green (Escherichia coli)
weak fermenter: pink around edges of colonies (Enterobacter aerogenes)
nonfermenter: remains dark purple (Proteus vulgaris)

70
Q

what type of fermenter and what are the color possibilities for MAC? what genes and species would be responsible for each?

A

strong fermenter: turns bright pink (Escherichia coli)
weak fermenter: turns light pink (Enterobacter aerogenes)
nonfermenter: entire plate, including growth, turns brown (Proteus vulgaris)

71
Q

This is a MAC plate, which genes and species is present?

A

Escherichia coli

72
Q

This is a MAC plate, which genes and species is present?

A

Enterobacter aerogenes

73
Q

This is a MAC plate, which genes and species is present?

A

Proteus vulgaris

74
Q

This is a EMB plate, which genes and species is present?

A

Escherichia coli

75
Q

This is a EMB plate, which genes and species is present?

A

Enterobacter aerogenes

76
Q

This is a EMB plate, which genes and species is present?

A

Proteus vulgaris

77
Q

This is a MSA plate, which genes and species is present?

A

Staphylococcus aureus

78
Q

This is a MSA plate, which genes and species is present?

A

Staphylococcus epidermidis

Microbiology Lab (11 decks)

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