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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
what is the name of the antibiotic resistance gene? what antibiotic is it resistant towards?
bla gene - resistant to ampicillin
26
Gram + or gram - : Bacillus subtilis?
gram +
27
Gram + or gram - : Escherichia coli?
gram -
28
Gram + or gram - : Staphylococcus aureus?
gram +
29
Gram + or gram - : Mycobacterium smegmatis?
acid-fast gram +
30
Gram + or gram - : Pseudomonas aeruginosa?
gram -
31
how did we apply our microbes in the temperature experiment?
lawn plate - use cotton swab with bacteria to cover entire plate, leaving no gaps
32
what were all the temperatures used in the temperature experiment?
4 25 37 42 47 60
33
Which temperature in °C is room temperature?
25 °C
34
Which temperature in °C is body temperature?
37 °C
35
What temperatures in °C is refrigerator temperature?
4 °C
36
Know how to convert temperatures.
°F = (°C x 1.8) + 32
37
What temperature did all species grow best at?
37 °C
38
What genus did not grow well at room temperature?
*Mycobacterium*
39
Why didn’t the bacteria grow at refrigerator temperature?
the bacteria underwent bacteriostasis in the cold temperature. Bacteriostasis being the slowing of microbial growth
40
what organisms were used in the antiseptic experiment?
*Escherichia coli Pseudomonas aeruginosa Bacillus subtilis Staphylococcus aureus Mycobacterium smegmatis*
41
How did we apply our microorganism to the surface of the antiseptic experiment?
Lawn plate: take cotton swab with bacteria and cover entire plate, leaving no gaps
42
What were the chemicals used in antiseptic experiment? what is its general chemical type?
Iodine – halogen 3% Hydrogen peroxide - Peroxygens 2% chlorhexidine - Biguanides 70% isopropyl alcohol – alcohol 1% formaldehyde - Aldehydes 1% silver nitrate - metal
43
How did we evaluate whether the antiseptic was effective or not?
an antiseptic was effective when its death zone was large an antiseptic was not effective when its death zone was small/nonexistent
44
Which organisms were the most and least resistant in the antiseptic experiement?
Most resistant – *Escherichia coli* Lest resistant – *Mycobacterium smegmatis*
45
which chemicals were most and least effective in the antiseptic experiment?
Most effective – 1% formaldehyde (largest death numbers) Least effective – 70% isopropyl alcohol
46
Which organisms were used in the antibiotic/antimicrobial experiment?
*Escherichia coli Pseudomonas aeruginosa Bacillus subtilis Staphylococcus aureus Mycobacterium smegmatis*
47
How did we apply our microorganism to the antibiotic/antimicrobial experiment?
Lawn plate: take cotton swab with bacteria and cover entire plate, leaving no gaps
48
What were the six antibiotics used for this lab exercise? their mode of action?
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
How did we evaluate whether the antibiotic was effective or not?
Larger death zone meant the antibiotic was effective Small death zone meant the antibiotic was ineffective
50
Which term is used to describe when a bacterium is easily killed by a particular antibiotic?
susceptible
51
what is narrow spectrum?
targets a single microbe group
52
what is broad spectrum?
inhibits/kills multiple types of organisms
53
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?
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
Which organisms were most and least resistant in the antibiotic experiment?
Most resistant: *Escherichia coli* Least resistant: *Mycobacterium smegmatis*
55
Which antibiotics were most and least effective in the antibiotic experiment?
Most effective: Chloramphenicol Least effective: Bacitracin
56
What is the definition of a selective media?
Inhibits growth of unwanted organisms (only the selected microbes live)
57
What is the definition of a differential media?
Allows organisms to grow but the added chemicals make them look different (they change different colors and/or precipitate is visible)
58
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?
(MSA) Mannitol Salt Agar (red) (EMB) Eosin Methylene Blue (dark purple) (MAC) MacConkey Agar (raspberry)
59
Which plate used in lab this semester is not selective or differential?
TSA
60
Which organisms used in selective/differential experiment are Gram + ?
*Staphylococcus aureus Staphylococcus epidermidis*
61
Which organisms used in selective/differential experiment are Gram - ?
*Escherichia coli Enterobacter aerogenes Proteus vulgaris*
62
how is MSA selective?
selects for gram + selects against gram -
63
how is EMB selective?
selects for gram - selects against gram +
64
how is MAC selective?
selects for gram - selects against gram +
65
how is MSA differential?
differential for mannitol fermentation
66
how is EMB differential?
differential for lactose fermentation
67
how is MAC differential?
differential for lactose fermentation
68
what type of fermenter and what are the color possibilities for MSA? what genes and species would be responsible for each?
fermenter: turns yellow (*Staphylococcus aureus*) nonfermenter remains red (*Staphylococcus epidermidis*
69
what type of fermenter and what are the color possibilities for EMB? what genes and species would be responsible for each?
strong fermenter: turns shiny metallic green (*Escherichia coli*) weak fermenter: pink around edges of colonies (*Enterobacter aerogenes*) nonfermenter: remains dark purple (*Proteus vulgaris*)
70
what type of fermenter and what are the color possibilities for MAC? what genes and species would be responsible for each?
strong fermenter: turns bright pink (*Escherichia coli*) weak fermenter: turns light pink (*Enterobacter aerogenes*) nonfermenter: entire plate, including growth, turns brown (*Proteus vulgaris*)
71
This is a MAC plate, which genes and species is present?
*Escherichia coli*
72
This is a MAC plate, which genes and species is present?
*Enterobacter aerogenes*
73
This is a MAC plate, which genes and species is present?
*Proteus vulgaris*
74
This is a EMB plate, which genes and species is present?
*Escherichia coli*
75
This is a EMB plate, which genes and species is present?
*Enterobacter aerogenes*
76
This is a EMB plate, which genes and species is present?
*Proteus vulgaris*
77
This is a MSA plate, which genes and species is present?
*Staphylococcus aureus*
78
This is a MSA plate, which genes and species is present?
*Staphylococcus epidermidis*

Microbiology Lab (11 decks)

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