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BIO 286 - Microbiology > Lab Quiz 8: Water Quality Testing, Genetic Transformation, Lactose Operon Regulation, and Enterobacteriaceae Biochemistry (Bio 286 - Microbiology) > Flashcards

Lab Quiz 8: Water Quality Testing, Genetic Transformation, Lactose Operon Regulation, and Enterobacteriaceae Biochemistry (Bio 286 - Microbiology) Flashcards

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1
Q

indicator organisms

A

always present when feces are present (PRESENT IN FECES); should be absent when feces are absent (ABSENT WITHOUT FECES); organism should be very EASY TO GROW; organism should be EASY TO IDENTIFY (using differential media); organism should persist in the environment slightly longer than the pathogens (there is less problem with false positives than false negatives)

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2
Q

fecal coliforms

A

indicator organism used to detect fecal contamination of mammals (humans); lactose-fermenting gamma proteobacteria

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3
Q

fecal streptococci (enterococci)

A

indicator organism used to detect fecal contamination of animals (like ducks) but not humans; glucose-fermenting bacteria

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4
Q

ratio of coliforms to streptococci

A

indicates where fecal contamination originated

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5
Q

wastewater is not contaminated

A

< 400 FC/100 mL

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6
Q

surface water is not contaminated

A

<160 FC/100 mL

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7
Q

drinking water is not contaminated

A

< 1 FC/100 mL

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8
Q

coliforms : enterococci ≥ 4:1

A

source of fecal contamination is human

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9
Q

2:1 ≥ coliforms : enterococci < 4:1

A

source of fecal contamination is a mix between human and animal

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10
Q

0.7:1 ≥ coliforms : enterococci < 2:1

A

source of fecal contamination is unknown

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11
Q

coliforms : enterococci < 0.7

A

source of fecal contamination is animal

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12
Q

mFC plate

A

used to detect FECAL COLIFORMS… selective with BLUE ACIDS… differential with LACTOSE… colony color is BLUE… incubation temperature is 44.5 degrees Celsius

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13
Q

mEA plate

A

used to detect FECAL STREPTOCOCCI (Enterococcus)… selective with SODIUM AZIDE… differential with GLUCOSE… colony color is RED… incubation temperature is 35 degrees Celsius

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14
Q

dilution calculation (calculating number of fecal coliforms or streptococci per 100 mL)

A

[(cfu * SDF) / volume plated] x 100

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15
Q

ratio of coliforms to streptococci calculation

A

Blue Colonies (fecal coliforms) / Red Colonies (enterococci)

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16
Q

bacteria can horizontally transfer genes through

A

transformation, conjugation, and transduction

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17
Q

Frederic Griffith

A

first described the process of transformation using rough and smooth strains of Streptococcus pneumoniae… mixing the dead smooth strain with the live rough strain killed injected mice, but live smooth bacteria were isolated from these dead mice… indicating that something had transformed the rough strain into a smooth strain

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18
Q

rough strain

A

made small compact colonies; avirulent when injected into mice

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19
Q

smooth strain

A

made larger mucoid colonies; efficiently killed mice when injected into them and could be isolated from the mice postmortem (Koch’s postulates)

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20
Q

heat killing the smooth strain

A

made them nontoxic

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21
Q

mixing the dead smooth strain and the live rough strain

A

killed injected mice (despite non being virulent when injected individually); live smooth bacteria were isolated from the dead mice because something had transformed the rough strain into a smooths train

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22
Q

Oswald Avery

A

proved that the transforming material was DNA

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23
Q

competent

A

bacteria that are capable of transporting exogenous DNA into the cell and incorporating it into their genomes (ex: streptococcus pneumoniae)

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24
Q

on the nutrient agar plate without antibiotics

A

all strains of the acinetobacter calcoaceticus grow… but quadrant 3 (with only the heat killed smooth strain) does not grow anything as only the DNA genomes are present

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25
on the nutrient agar plate with antibiotics (streptomycin)
only the smooth, resistant strain (quadrant 1) and the transformed rough -> smooth, resistant strain (quadrant 4) grows because the rough strain (quadrant 2) is susceptible and quadrant 3 only contained DNA
26
Griffith's transformation experiment -- quadrant 1
grow the rough, susceptible strain
27
Griffith's transformation experiment -- quadrant 2
grow the smooth, resistant strain
28
Griffith's transformation experiment -- quadrant 3
heat kill the smooth, resistant strain
29
Griffith's transformation experiment -- quadrant 4
mix the dead smooth strain with the rough, susceptible strain
30
proteins encoded by the lac operon
β-galactosidase (product of lacZ gene), lactose permease (product of lacY gene), and lactose transacetylase (product of lacA gene)
31
lac transcript is polycistronic
it contains more than one coding sequence
32
lacI
lac repressor; tetramer of four identical subunits... it binds to DNA near lac promoter and prevents transcription of the structural genes and it binds to the INDUCER (allolactose)-- this is cooperative [binding of one molecule of inducer makes binding of the next one more favorable... repressor binds inducer in all or none fashion]... or it binds to the OPERATOR (lacO) which partially overlaps promoter [allows RNA polymerase to bind to promoter and form an open complex but not to elongate transcription]
33
lacI^s
REPRESSED EXPRESSION; proteins never leave operator
34
lacO^c
loss of repressor binding; CONSTITUTIVE EXPRESSION
35
merozygote
two copies of the relevant control genes exist
36
Jacob and Monod
used fertility plasmid (F) from E.coli to study regulation of lactose operon; used a variant (F') that contained a normal functional copy of the lactose operon genes (normal LacI and LacZ proteins)
37
ONPG
a colorless chemical analog of lactose used to measure enzyme activity of LacZ... when cleaved by LacZ it become yellow ortho-nitrophenol
38
two grey tubes -> one grey and one pale yellow
lacZ
39
one grey and one pale yellow -> one grey and one bright yellow
WT (wild type)
40
two pale yellow tubes -> one grey and one pale yellow
lacI-
41
two pale yellow tubes -> one pale yellow and one bright yellow
lacO^c
42
two grey tubes -> two grey tubes
lacI^s
43
enterobacteriaceae
family of gamma proteobacteria that includes Escherichia, Salmonella, Yersinia... BACILLI that are typically 1-5 micrometers in length... stain GRAM NEGATIVE and are FACULTATIVE ANAEROBES... can ferment sugars (all can ferment glucose and some can ferment lactose) and reduce nitrate to nitrite via ANAEROBIC RESPIRATION... generally LACK CYTOCHROME C OXIDASE... most have FLAGELLA... NON-SPORE FORMING... PRODUCE CATALASE
44
coliforms
Members of the family enterobacteriaceae that ferment lactose
45
MacConkey agar
if the microbes ferment lactose then the acids they produce turn the indicator dyes red... a positive result is red and a negative result is no change
46
indole
if microbes breakdown amino acid tryptophan to indole, the indole reacts with Kovac's reagent to turn bright red... a positive result is red and a negative result is yellow
47
triple sugar iron agar (slant)
if ammonia is produced then the pH of the media becomes neutral -- red and if lactose/sucrose is fermented then the tube will remain yellow... a positive result is yellow (A) and a negative result is red (K)
48
triple sugar iron agar (butt)
the butt of the TSI is always yellow -- a positive result is yellow (A)
49
triple sugar iron agar (gas)
gases produced during fermentation will appear as bubbles or cracks... a positive result is cracking and a negative result is no change/no cracking
50
triple sugar iron agar (H2S)
hydrogen sulfide produced from breakdown of amino acid cysteine reacts with the iron to form ferric sulfide which is black... a positive result is black and a negative result is no change
51
MRVP (methyl red)
turns red in the presence of organic acids... a positive result is red and a negative result is yellow
52
MRVP (voges proskauer)
detects acetoin to turn red in its presence... a positive result is red and a negative result is coppery brown/no change
53
citrate
at acidic pH (citrate present) the media is green and if the citrate is metabolized the pH will turn blue... a positive result is blue and a negative result is green
54
urea
under alkaline conditions the indicator will turn pink... a positive result is bright pink and a negative result is yellow/no change
55
indole negative result
yellow
56
indole positive result
RED
57
methyl red negative result
yellow
58
methyl red positive result
RED
59
voges proskauer negative result
no change (yellow brown)
60
voges proskauer positive result
RED
61
citrate negative result
green
62
citrate positive result
BLUE
63
MacConkey Agar (MAC) negative result
no change (not red-- brown or tan)
64
MacConkey Agar (MAC) positive result
RED
65
urea negative result
no change (yellow)
66
urea positive result
PINK
67
TSI (slant) negative result
K - red
68
TSI (slant) positive result
A - YELLOW
69
TSI (Butt) negative result
K - red
70
TSI (Butt) positive result
A - YELLOW
71
TSI (gas) negative result
no change/no cracks
72
TSI (gas) positive result
CRACKS
73
TSI (H2S) negative result
no change/yellow
74
TSI (H2S) positive result
BLACK

BIO 286 - Microbiology (21 decks)

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