Microbial Detection Of Contaminants Flashcards
1
Q
Hepatitis B; a viral contaminant?
A
False
Hepatitis A and norovirus
2
Q
Listeria is a ….(Viral/ bacteria/fungal)
A
Bacteria
3
Q
Parasitic contaminant
Examples
A
Toxoplasma gondii
Tape worm
4
Q
Advanced microbiological contaminant detection tool
A
Nucleic acid based
(PCR, Thermal amplification, Gene chip, probe, biosensor)
5
Q
UV Vis spectroscopy can be used to detect organic and biomolecules that are (small/large) from even SMALL samples
A
Small
6
Q
Nano particles and their … property is used in …technology
A
SPR (surface plasma resonance)- light deprndant property
UV Vis spectroscopy
7
Q
Beer Lambert law
Transmitance to absorbance used in ..tech
A
UV vis spectroscopy
8
Q
UV vis can detect concentration of soecific constituent
A
True
9
Q
Uv vis enhanced spectroscopy uses nanoparticles and is ..(more/less) sensitive than uv vis spectroscopy
A
More
10
Q
SPR property is used in nano particle based labelling of constituents in
A
UV vis EXTENSION spectroscopy
11
Q
Extension coefficient= ….+…
And is associated with ..tech
A
Absorption+ scattering
Uv vus extension spectroscopy
12
Q
Using uv vis EXTENSION spectroscopy we can find conc of a wide variety of constituents?
A
True
13
Q
Different size and shaped nanoparticles are used in un vis EXTENSION spectroscopy
A
True
14
Q
Disadvantages of uv vis extension spectroscopy
A
- masked in fod matrix if uv vis active food particle/ smaller food particle
- Complex peaks- only slight shift - difficult to interpret
- False +/- ( large matric components )
15
Q
…and … chromatography tech are welll established in food contaminant testing due to their ability to
A
Gas
Liquid chromatography
Seperate complex mixtures
16
Q
Major chromatographic techniques used in detecting contaminants
A
HPLC
UPLC
MDC
high pressure liquid chromatography
Ultra performance lc
Multi dimensional c
17
Q
Using high pressure in chromatography helps detect even smaller molecules
HPLC
UPLc
Was introduced in the years
A
1973
2004
18
Q
HPLC was proposed in ..as an alternative to… chromatography to detect….(Volatile/soluble ..) And which are heat ..(stable/unstable)
A
1973
Gas chromatography
Less volatile
Heat unstable- degrades at high temp
19
Q
….is used to detect less volatile substances that would degrade at high temperatures
A
HPLC
20
Q
… chromatography has higher peak seperation, sensitivity , speed and resolution and which could detect over 50 components , usually coupled with …. technique
A
UHPLC/ UPLC
Tantem mass spectroscopy
21
Q
In multi dimensional chromatography different chromatographic techniques are compiled by using …multiple columns?
This will increase seperation efficiency in complex matrices
A
True
22
Q
Limitation of chromatography in food contaminant detection
A
Cannot detect bacteria
Proteins
Larger molecules
Has limited range of analyte ( property and complementary sp and mp difficult)
23
Q
Pesticide residues
Fungal or mycotoxin
Like smaller molecules can be detected using chromatography but cannot detect
A
Bacteria
Protein
Larger molecules
24
Q
Disadvantages of chromatography
A
Time
Analyte range limited
Cannit detect bac/protein..
Not for field
Expertise
Coupling with other tech for quantification
25
Tantem mass spectroscopy is usually coupled with...(UPLC/HPLC/MDC
Uplc
26
Protein based detection tech is
Immuno assay
- LIFA - lateral flow IA
ELISA
Radio IA
Chemi luminous IA
Counting IA
27
Most commonly used protein based detection techniques under ... technology are .and ..
Immuno assay
LFIA
ELISA
28
...is a bioanalytical technique that could measure presence and concentration of analyte using bio recognition agent
Immuno assay
29
..looks similar to pregnancy detection kit and are used in home or point of care and lab use
LFia
30
...has 4parts and uses capillary force ; diagnostic; screen agriculturally relevant protein, small molecules etc
Parts are.....
2° antibody is fixed in ...part
LFIA
Sample pad ( with antibody)
Conjugation pad( reaction between sample and anti body)
Nitrocellulose mambrane( with 2° antibody)
Absorbent pad( absorb excess)
31
Among IA techniques, only in....(LFIA/ELISA) multiplexing can be done
LFIA
32
...can detect simultaneously a variety of bacterial pathogen
LFIA
33
LFIA is quantitative?
No
Pregnancy kit (can't say how much component present)
34
LFIA is rapid with a period of.....to...
5-30minutes
35
iA is a bio analytical technique that uses bio recognition molecules. All IA tech are quantitative and qualitative?
False
LFIA is not quantitative
But ELISA is inherently quantitative
36
Read outs can be enhanced in....
Multiplexing is possible in...
...is quantitative also
...is not
ELISA
LFIA
ELISA
LFIA
37
Advantages and disadvantages of LFIA
Rapid (5-30min)
Lab, home, on point detection
Multiplexing
Simultaneously detect seceral bacterial pathogens
High sensitivity and specificity
Storage important- antibody degradable
Loss activity over time
Need further confirmation test as
Cannot enhance read out using enzymes
Sensitivity can't be enhanced
False +/-
Only qualitative
38
LFIA uses enzymes as bio recognition agent
No
Antibody (1°, 2°)
39
Unlike LFIA sensitivity can be enhanced in ....by linking.....but cannot be multiplexed
ELISA
Antibody to an enzyme
40
Compare LFIA and ELISA
Lifa only qualitative but multiplexing possible, uses no enzyme and read out cant be enhanced, shorter active period of antibody makes further confirmation test
Elisa is inherently quantitative and qualitative, but cannot be multiplexed but read outs are enhanced
41
Antibody is linked to an enzyme which in term gets activated and convert a colourless substrate coloured
ELISA
42
ELISA can detect a variety of molecules but not simultaneously?
True
43
Direct, indirect, competitive, sandwich are types of ...
ELISA ( Protein based IA)
44
How is direct ELISA different from indirect ELISA
Direct ELISA uses only one antibody immobilised
Indirect uses 1°, linked to 2° which is linked to enzyme
45
...is a 2 step process (ELISA) Which uses ....antibody and ...enzyme( number)
2 primary and secondary antibody
1 enzyme 2° linked to this enzyme
46
...is a 2 step process (ELISA) Which uses ....antibody and ...enzyme( number)
2 primary and secondary antibody
1 enzyme 2° linked to this enzyme
47
Among direct and indirect ELISA , direct is more sensitive as in this antibody is directly linked to the enzyme
False
Indirect is more sensitive as it has 2 antibody
48
In sandwich elisa number of antibody used is ...
Capture antibody
1° antibody +/- 2°
ie two or more
49
In sandwich elisa the immobilised antibody is called ...
Capture antibody
1° &/ 2° are added later
50
The two antibody used in sandwich elisa should have same epitomes
False
Should have different epitomes
51
Reference antigen, analyte preincubation are part of ...
Competitive ELISA
52
Relation between signal and analyte (sample) concentration in competitive ELISA is
Inversely proportional
Reference antigen is coated in the well to this preincubated analyte - antibody complex added and washed, if analyte conc high, it will replace more reference antigen...which decreases signal strength
53
Pregnancy test: LFIA
Allergen test:
ELISA ( protein based)
54
Which is more rapid LFIA/ ELISA
LFIA (5-30 min)
ELISA (<24 hr)
55
Advantages and disadvantages of ELISA
Adv
Rapid
High sensitivity can be enhanced as well
Enzymes more shelf stable than antibody based as if LFIA
Inherently qualitative and quantitative
Cannot be multiplexed
Costly (to develop reference antigen)
Time consuming preparation
Not out of lab
Expertise needed
56
Raman scattering is ..elastic or inelastic
Inelastic change in tnergy and momentum frequency and wavelength
57
Most common form of scattering ( elastic or inelastic
Elastic
Inelastic only 1/10^ 6
58
Inelastic scattering: CV Raman
Elastic scattering:
Reilang
59
... scattering is used in ...tech
Inelastic
SERS
60
UPLC: 2004
HPLC: 1973
SERS:... also full form
1974
Surface enhanced raman scattering
61
Inelastic scattering is rare and each constituent gave particular pattern of scattering because of difference in unbound electrons in them
True
62
...is a dynamic technique and produces "fingerprint" spectrum and could even detect molecule level of component
SERs
63
Adv & Disadvantage of SERS
Could detect even VIRUS, protein, small molecule
Sensitive
Complex output
64
Although sers is sensitive and could even detect virus, its industrial applications is limited why?
Complicated spectrum
65
...uses mostly biological molecules like enzyme, antigen, antibody, ligand etc to neasure both qualitatively and quantitativly by producing USER FRIENFLY output using a ....to change physical/ chemical changes to signals
Biosensors
66
Output signal ~ analyte concentration in biosensors
True
67
Components of biosensor
Analyte- bioreceptor - transducer- amplifier- electronics- interface/ monitor
68
In a biosensor bioreceptor is actually
Molecular recognising material ( DNA, enzyme, antibody, whole cell, micro organism
69
Transducer produces electric signals from chemical, physical , electrical changes happening, transducers examples
Thermister
Proton counter (pH)
Semiconductor
Poezoelectric device
Electrodes
70
...are the key features required for signal generation in a biosensor
Specificity and selectivity of receptor for analyte
71
Adv of biosensor
Scalability
Selectivity
Specificity
Detect even small concentration
Rapid
Portable- miniature size- cop low
72
Electrode passivation,
Bio fouling
Are disadvantages of
Biosensors
73
Disadvantages of biosensors
Biofouling
Electrode passivation
Affected by pH, temperature changes etc
Bioreceptor production makes it expensive
Low life span or activity lost during storage
74
Biosensors can be classified based on...and .
Bioreceptor
Transducer element
75
Biorecognition based bioreceptor classification are
1) catalytic
2) affinity
Examples for each?
Catalytic : enzyme, micro organism, TISSUE
affinity: antibody, WHOLE CELL
( affinity- cell)
Catalytic- tissue
AC
CT
76
Microorganisms based biosensors are ...( Catalytic/ affinity)
Affinity
Affinity- anti BODY-mo, CELL-
77
Transducer based biosensors classification are
ELECTROCHEMICAL- potentiometer, conductometric, amperometric, ION SENSITIVE FIELD EFFECT
OPTICAL- absorbance based, spr based, fluorescence based, luminescent based
PIEZOELECTRIC- surface accoustic wave bases, bulk accoustic wave based
THERMAL
78
IS FET: ....is a ....
ion Sensitive Field Effect transducer based biosensor
79
Widely used biosensor in food contaminant detection is .....which is...classification of biosensor
ISFET
Transducer element based- electrochemical transducer
80
Electrochemical sensing tech compiled with ISFET are
Impedemetric aptasensor- binding events - dna based
SWV- square wave voltametric electrode- redox of target
Amperometric electrode
81
Food borne pathogens are generally detected through...
Nucleic acid based tech
82
Asvantage of na based tech over traditional tech in detecting fb pathogens
Disadvantage
Rapid - min to hrs
Expertise needed
83
Year of development
HPLC
UPLC
SERS
PCR
1973
2004
1974
1986
84
NA based tech are
PCR - ( RTqPCR, mPCR, nested PCR)
Isothermal application -(LAMP, NASBA)
Gene probe
Gene chip
85
Pcr tech developed by....in...yr
Kary mullos
1986
86
Pcr can multiply only a part of dna sequence?
No
Part or wholly
87
PCE as a food borne pathogens detection tech is advantageous as
It can distinguish between
Bac virus or fungi
Can multiply sample for further analysis
88
Primers are sequences with.,.bps
15-20 bp
Ss na sequence
89
Pcr technique needs thermal cycle because different steps need different temperatures
Denaturation-
Anhealing-
Extension -
95-96 °C
55-65 °C
72°C
90
PCR tech used to detect or amplifying specific region
Nested pcr
91
RT q PCR stands for
Real Time fluorescent quantitative pcr
92
Reverse transcription pcr is used when
Ss rna needs to be converted to ds dna
93
mpcr stands for....and is used to...
Multiplex pcr
Detect multiple species ( virus,yeast, e coli...)
94
Most widely used pcr tech
RTqPCR
real time
No need for further electrophoresis
95
Widely used pcr tech
Rtqpcr> mpcr
96
Nested pcr is used when target area is long ....bp
14-50 bp
(Primer 15-20)
97
Number of primers used in nested pcr
2
Outer and inner
98
Stages of RTqPCR
2
Reverse transcription
Amplification
99
RTPCR is quantitative because thyough.
.and ....we can understand
Levrl of fluorescence- quantity
Earliness of fluorescence - conc
100
Adv of RTPCR
Real time
More sensitive
101
Different types of rtpcr
Dye based- SYBR green
Probe based- taq man
102
SYBR green - working
Is dye based rt pcr tech
The dye is an interchalating agent that would chalate only in ds nucleic acids
Therefore dye appears if complementary sequence is present during extension phase
103
..tech uses a primer with reporter molecule and a conjure molecule. Only when polymerase enzyme acts, reporter is cleaved from conjure and then colour appears
Taq man - probe based pcr
104
...tech uses an interchalating agent to detect once ds dna appears
SYBR green - dye based pcr
105
A novel NA based tech
Isothermal application
106
In...tech uses different primers in a cycle
m pcr
107
Advantages &Disadvantages of m PCR
Rapid
Specific (uses target × 2 primers) (forward and reverse for each target)
Cannot distinguish dead and live -false +/-
Cannot identify, only detect
108
Compare rtpcr to isothermal
Pcr has limited industrial application due to need for expertise and cost of instrument and complexity
Unlike isothermal
Rapid, no specialized equipment hence no expertise
109
Different types of isothermal application are ....and their difference
LAMP- Loop Mediated isothermal AMPLIFICATION- used for dna
NASBA- nucleic acid sequence based amplification - rna
110
Temperature maintained in LAMP & NASBA
Lamp- dna - 60-65
(Pcr- 95-96, 55-65, 72)
Nasba- rna - 41
111
Which one is more sensitive LAMP or PCR
Lamp
Forms complex structure of dna maintaining a loop- which makes its detection easier
Both are real time
112
In lamp amplified sequence must have bp less than ...bp
300
113
LAMP gives complex dna structure which makes detection more easy and rapid....(time)
30-60 min
114
Adv amd disadvantage of lamp
Rapid (30-60 min)
Mote sensitive than pcr
More primers used 4-6
Sequence should be less ir equal to 300bp
False result if improper primer pairing
Cross contamination possible
115
LFIA : 5-30 min
LAMP:
30-60 min
116
LAMP : DNA
....: RNA
NASBA
117
Sequence of steps and enzymes in NASBA
Reverse transcription: RNA-- ds c dna
RNase H: digest rna strand ; ds dna-- ss dna
T7 RNA Polymerase : ssdna-- rna ( multiplication)
118
Isothermal amplification techniques are rapid
True
119
Gene robe tech is a novel newly developed tech?
False
45 year long before
1975
120
Both primers and probes are ss, later one cannot initiate amplification?
True
121
Gene probe tech uses gene characteristics like....n....
Gene selectivity ( its base complimentaritt based)
Repeatability
122
Types of gene probe tech are ..n...
Gene chip
Micro dna
123
Gene probe tech: southern: 1975
Gene chip: southern: ...
Hplc
Uplc
Sers
Pcr
1989
1973
2004
1974
1986
124
Principle behind gene chip
Nucleic acid hybridization
125
Na hybridisationin gene chip can give only qualitative infrence
False
Signal strength can give both quantity and quality
126
Asv and dis of gene chip or gene probe
Sensitive
Specific
Multiplexing- Can study 1000 of genes simultaneously
Rapid
Accurate
Quantitative and qualitative
HIGH THROUGHPUT
Though easy to operate, making process, isolating and synthesis of probe need expertise and costly
COMPLEX data anslysis
Skill
127
Gene chip is also called
Micro array
128
How many people are affected by food borne illness annually
1/10
129
Who first used sers
Martin fleischman
130
FET cannot effectively detect which pathogen ( bac/virus/fungi/parasite)
Parasite
Larger hence ionic variation cannot be sensed by isfet as it has low sensitivity and resolution
131
mpcr can lead to false positives and cross contamination
It cant distinguish live and dead
132
Isothermal amplification can amplify dna, rna and protein
False.not protein
133
Gene probe: complimentarity based
Gene chip: NA hybridisation based
True
134
ISFET: inefficient in detecting parasites but could detect toxin, bac, virus
SERS Inefficient in detecting virus
Why
ISFET: Parasites are larger conparitively, hence the ionic difference oroduced by them is not effectively identified by isfet because of its low resolution and sensitivity
SERS can detect virus only if their is active molecule or they might not come to the surface or sers substrate
135
ISFET is not suitable for on site?
False
Smaller size and highly portable
136
PCR can detect both live and dead but cannot distinguish
True
137
ELUSA is a versatile tech which can detect even pesticide residue, mycotoxin and virus using appropriate antibody
True
138
Best tech for detecting allergens in food
ELISA
139
GMO in foid can be detected using..n ...
PCR
NGS
140
Biosensors can even detect heavy metals
True
