BB test MCQ Flashcards
(110 cards)
1
Q
coliforms
A
ferment lactose and produce acid and gas at 37 degrees. Indicate faecal contaimation of water
2
Q
bile salt broth
A
liquid version of maccokney agar
3
Q
what does bile salt broth select form
A
coliforms
4
Q
detect presence of coliforms in bile salt broth
A
acid makes tube turn yellow and gas shown in durham tube
5
Q
calculation for CFU
A
times number of cfu on plate with the dilution factor and divide this by the volume of the sample plated
6
Q
river sample centrifuged
A
removes bacterial cells leaving only phage and viruses
7
Q
bacteriophage
A
viruses that infect bacteria
8
Q
3 main properties of phage
A
head-tail, icosahedral, filamentous/helica
9
Q
what are phage classified on?
A
nuclic acid and replication, ICTV, morphology, host rang
10
Q
what classification are T-even page in?
A
baltimore class 1, dsDNA
11
Q
how to T-even phage use the host, method?
A
injects nucleic acid down through tail and base plate
12
Q
T-even phage shape
A
elongated icosahdral head, helical tail with sheath, base plate
13
Q
T-odd phage shape
A
icosahedra head, short rudimentary tail, sheathless and non-contactile
14
Q
T-odd phage classification
A
baltimore 1 dsDNA
15
Q
bacteriophage lambda shape of head
A
icosahedral, non enveloped
16
Q
bacteriophage lambda shape of tail
A
sheathes, rudimentary base fibres
17
Q
staphylococcus phage twort shape
A
6 tail fibres, contractile, icosahdral head, double base plate
18
Q
salmonella phage v11 genome
A
large genome, baltimore 1, dsDNA
19
Q
salmonella v11 shape
A
contractile tail with sheath. star shaped fibres with a thin base plate. icosahedral head. non-enveloped.,
20
Q
icosahdreal phage ox174 classification
A
Baltimore 2, ssDNA
21
Q
shape of the icsahdral phage ox174
A
no tail
icosahedral head
non-enveloped
22
Q
pseudomonas phage classification
A
group3, dsRNA
23
Q
psuedomonas phage shape
A
linear segments of RNA
icosahedral head
enveloped
24
Q
bacterial phage ms2 classification
A
Baltimore 4, ssRNA genome
25
bacterial phage shape
icosahdral capsid
| non-enveloped
26
filamentous phage m13 genome classification
baltimore 2
circular ssDNA
small genome
27
m13 type of infection
chronic infection
| infect certain bacteria with certain plasmid
28
filamentous m13 phage shape
helical
| proteins on each end for recognition of host to bin
29
what is the virulent lifestyle
bind to host and infect the genome
| phage particles burst out of the cells
30
chronic lifestyle
progeny not released
slow growth rather than killing
released by extrusion from host cell membrane
not lethal
31
temperate lifestyle
phage integrate passively into the host
this is then passed onto the daughter
if the environment turns unfavourable the phage can then enter the lytic cycle
32
how does a plaque assay work
uses lytic bacteriophage
| when they are released from the cell is causes an infection
33
what does a clear plaque show
lysis
34
what does a cloudy plaque show
not chronic infection but some still released from the cell
35
how are pili used for host specificity
if a host has the F-plasmid, the phage can make the F pilus. they do conjugation and draw the host towards themselves and binds inserting the genome
36
what is phage typing
phenotypic classification of strains of bacteria
| serovars have different surface antigens, use library of phage to see what these antigens are on the isolate
37
what is phage display
used for drug discovery
| typically uses coliforms
38
how have bacteria adapted to be resistant to phage?
adapt cell surface receptors
proteins to mask the receptor
phage adsorption
phage can also develop to get over this though
39
what likely led to micorbial diversty
increase in atmosphere oxygen
40
define taxonomy
classification of organisms into groups
41
defien phylogeny
evolutionary relatedness of species
42
how are microbial species grouped
collection of strains with similar stable properties but differ significantly from other group
their G/C content should be similar and above 70% DNA-DN hybridization
43
stain definition
descendents of a single pure microbial culture
44
biovars
biochemical physiological cultures
45
morphovars
morphological variants
46
serovars
serlogical.antigenic variants
47
pathovars
pathogenic variants
48
what is polyphasic taxonomy
multiple classification for species and identifcation of a novel microbe
49
what is phenotypic classification
traits of the microbe are used to estimate general similarity
morphology and physiology are used
50
what is phylogenetic classification
assess the evolutionary relationships between the organisms
| typically compare the ribosomes, 16S rRNA
51
genotypic classification
genetic similarities compared
| 70% homology at DNA hybridisation
52
morphology classification looks at:
```
microscopic factors
staining behaviour
spore behaviour and location
motility mechanisms
cellular inclusions
```
53
physiolgical and metabolic classification features
```
cell wall components
energy sources
carbon and nitrogen utilisation
fermentation products
secondary metabolites such as antibiotics
```
54
biochemical classification features
fatty acid ester analysis
proteins produced in the cell
each species gives a different profile
55
ecological classification features
colonisation of niches
pathogenesis
symbiotic relationships
56
how are molecular characteristics compared?
nuceic acid base
hydridisation
sequencing
genomic fingerprinting
57
what is nucleic acid base composition?
determined either by genome sequencing
difference in 10% in G?C content suggests different groups
DNA duplex forms base pairs, G/C content of a species can define it
58
what is nucleic acid hybridization?
heat and cool the two organisms dna to form links
| complementary strands form links and this can tell you how similar two bacterium are
59
how is nucleic sequencing used for classification?
small sub-units of ribosomes
there are certain position on bacteria where they rRA differs
oligonucleotide sequences observes, these are essential and highly conserved and not subject to HGT s good for species identification
60
how is genomic fingerprinting used for classification
restriction mapping
PCR amplifies the rRNA gene and digest this with restriction enzymes
electrophoresis
ribotyping
61
what is MLSA: multilocus sequence analysis
microbes and species level
| compare 5-7 housekeeping genes which evolve quickly
62
why does MLSA use multiple genes?
accounts for horizontal gene transfer
63
what is MST: multicolous sequence typing
identification of strains in a very similar way to MLSA
64
what is SNP: single nucleitide polymophism?
polymorphism in a specific gene or non-coding region
| conserved regions typically have evolutionary change which can be used
65
how are phylogenetic trees made?
align the sequence
examine the sequence for pylogentic signals
choose tree building method: distance or character
test the ligitimacy using bootstrapping
66
what is the core genome?
set of genes found in all members of the species
they are essential for the microbe to survive
housekeeping genes
67
what is an accessory genome?
more recently acquired
non-essential
enable colonisation of new niches
often gained through HGT
68
what is a pan genome?
combination of all genes found within a taxonomic group
| core and accessory combined
69
what is horizontal gene transfer
prokaryotes can exchange genetic material
| bacteria can acquire gene from environment or other bacteria
70
what is transformtion
captures DNA from envronment
| it goes through the membrane and incorprated into the genome
71
transduction
bacteriophage tranmit DNA between bacterous
| phage can go wrong and take up bacteria DNA instead of viral and injects into into a new bacteria
72
what is conjugation
sexual respoduction
required certain plasmids
sex pilus is made and fuses with other bacteria to transfer the plasmid
73
transduction
bacteriophage transmit DNA between bacteria
| phage can go wrong and take up bacteria DNA instead of viral and injects into a new bacteria
74
what is conjugation
sexual reproduction
required certain plasmids
sex pilus is made and fuses with other bacteria to transfer the plasmid
75
main features of proteobacteria
all gram negative
| frequenly motile
76
main groups withing proteobacteri
```
Alpha
beta
gamma
detla
epsilon
```
77
what is Rickettsia?
an alphaproteobacteria
| but not typical for thi group
78
characteristic of rickettsia
```
strit
invades and survives inside cells
obligate intracellular
small rods
pelomorphic
```
79
why has rickettsia undergone gene reduction
it can get most substrates fro its environment so doesnt need the genes to make it
eg takes in atp from cell instead of making it
80
what does rickettsia do/cause?
can sometimes be pathogenic causing fever and typhus
81
what is rhizobium
beneficial bacteria in alphaproteobacteria
| symbiotic with plants
82
chrcteristics of rhizobium
gives plant a source of nitrogen
| it fixes nitrogen transferring ammonia to the plant
83
how does rhizobium help plants
bacteria makes nod factors and plants respond by allowing the invasion and making flavonoids
84
what type of bacteria does alphaproteobacteria largely contain
oligotrophic proteobacteria, capable to grow at low nutrient levels
many are adapted to live within plants and animal cells
85
what different between alpha and beta proteobacteria
overlap metabolically but beta tend to use substances that diffuse from organic decomposition in anoxic environments
86
what is the main type of bacteria in the beta group
chemolithotrophs
87
what type of pathogens are in the beta group
neisseria
bordetella
burkholderia
88
what is neisseria?
diplococci, non motile
| causes menigitus and gonorrea
89
what vaccines are there for neisseria
variable proteins on the surface makes it hard
| vaccines typically target the capsule and different subtypes have carbohydrate differences in this so this is targeted
90
which is the laregst group of proteobacteria?
gamma
91
which is the most common gamma bacteria?
purple sulphur bacteria
92
key facts about detalproteobacteria
smaller group but still diverse
| sulphur and sulphate reducing bacteria
93
key facts about epsilonproteobacteria
very diverse
| inhabit extreme environments such as hydrothermal vents and acidic mucosa
94
main group of epsilonproteobacteria
campylobacter
95
what is campylobacter
```
causes gastroenteritus
curved rod morphology
microaerophillic
present in most animals gut but not always pathogenic
motile
```
96
what is helicobacter
H.pylori can cause gastric and peptic ulcers
| they use amino acids is primary carbon source and live in the stomach mucosa
97
how does purple sulfur bacteri work
it depositis interanl graules of sulphur inside itself
| use hydrogen sulphide as electro donor, oxidises this to sulphur and despotis it inside
98
characteristics of purple sulphur bacteria
photolithoautotroph
| strict anaerobes
99
why are purple sulphur bacteria important
used in bioremediation and biotech applications
100
key factors of the order psuedomonaledales
```
cheomorganotrophs
strict anaerobes
use nitrate as terminal acceptor in anaerobic respiration
free living
motile
```
101
what is P.aeruginosa
ressitant to may antibiotics
large number of genes for metabolism
used as a model for inter-cell communication and biofilm formation
102
what is an enterobacteriacaea
facultative anaerobe
clinically significant
characterised by fermentation products
103
why is ecoli a model organism
earliest bacteria to e studied for biochemistry
| cheap and simple nutrition requirements
104
how can ecoli be used as a faecal indicator
used by the water inductry to show contaiminationit survives but doesnt reproduce in water and signals a recent contaimination
shows potential present of dangerous bacteria such as enteric pathogens.
105
how does ecoli become a pathogen
different strains pick up different and new genes
106
how does ETEC work
enterotoxigenic, secretes a cholera like toxin, salt imbalance
107
how does EPEC work
enteropathogenic
| injects eeffector proteins that interfere with pathways
108
how does EHEC work
shiga toxin
travels to kidney and causes disease
can be life thretening
109
how does EAEC owrk
enteroaggregative
produced surface fimriae that binds to surface and each bother foming a biofilm
may also secrete enterotoxins
110
how does ecoli develop to be pathogenic
```
pathogenic genes might be added on
not essential
they can also pick up a plasmi HGT
LT toxin plasmid encoded
LEE variance fator
ST toxin integrated into genome
eg shiga toxin
```
