exam 1 Flashcards
1
Q
describe gram (+) bacteria
A
- thick cell wall (peptidoglycan)
- stains purple
- only 1 membrane
*contains teichoic acid
2
Q
describe gram (-) bacteria
A
*contains inner and outer membrane
*has cell wall (peptidoglycan)
*contains periplasmic space (between membranes)
*stains pink
*contains LPS
3
Q
what is an endospore vs. a vegetative cell
A
endospores are dormant form a bacterial cell and it is produced by bac to survive harsh environments. vegetative cells are the metabolically active growing bacteria
4
Q
what is gram (+) acid fast?
A
a gram positive acid fast is a cell in which contains mycolic acid (glycolipids aka less susceptible to antibiotics) and does not stain with gram stain. An example of this would be mycobacteria.
5
Q
define fimbriae
A
short bristle proteins projecting from cell surface. play role in adhesion
6
Q
define pili
A
longer protein that aid in attachment/conjugation
7
Q
define capsule
A
located outside of cell wall and facilitate bac adhesion to surfaces and other bacteria
8
Q
what are the 3 differing views of pathogenesis with example?
A
- bac evolved to cause disease in humans (t.pallidum)
- bac evolved to colonize certain sites within humans and cause disease when not in equilibrium (staph)
- disease occurs when bac accidentally infect humans (legionella)
9
Q
what are kochs postulates?
A
- suspected germ must be present in every case of the disease
- germ must be isolated and grown in pure culture
- cultured germ must cause disease when inoculated in healthy susceptible experiment host
- same germ must be reisolated from diseased experimental host
10
Q
what are some complications with kochs postulates?
A
- bacteria can be hard to culture
- symptoms vary throughout host
- individuals can be asymptomatic
- pathogen can be dormant
11
Q
what are modern alternatives to kochs postulates?
A
- non culture detections
- treatment that eliminates microbe should prevent disease
- reduced exposure = reduced disease
- compare disease in related pathogens
12
Q
define dysbiosis
A
change in bac community -> can result in disease
13
Q
what are molecular koch postulates?
A
- property under investigation should associate with pathogenesis member of genus or strain of species
- inactivation of genes associated with suspected virulence should to lead to measurable loss in virulence
- reversion of mutated gene should lead to restoration of pathogenicity
14
Q
what are survival curves?
A
looks at percentage survival
15
Q
what is biophotonic imaging?
A
you get image of bacteria and can follow animal overtime
*use of fewer animals
16
Q
define LD50
A
lethal dose 50 - how much of bacteria needed to get 50% mortality
17
Q
define ID50
A
infectious dose 50 - how much bacteria needed to lead to 50% of the population infected
18
Q
define competition assay
A
mix wild type and mutant bacteria and see which one grows better and measure ratio
19
Q
what is competitive index equation
A
[cfu mutant / cfu wild type] over [cfu mutant / cfu wild type]
output ratio / input ratio
20
Q
define gentamicin protection assay
A
measuring adherence and invasion through a tissue/cell culture
21
Q
how do you do adhesion gentamicin protection assay?
A
wash unattached bac away then lyse and count bac
22
Q
how do you do invasion gentamicin protection assay?
A
add gentamicin then wash then lyse and count bac
23
Q
what is an invasion success curve
A
measure bimax aka maximum number of internalized bacteria and moi aka multiplicity of infection and minmoi which is minimum inoculum to reach bimax
24
Q
define plaque assay
A
can only do if bac kills host cell and bac has to be able to spread
25
for plaque assay, what is the different between small and large plaques
small plaque -> bacteria moved slowly
large plaque -> bac moved well cell to cell
26
define fluorescent microscopy
used to visualize what bac are doing
27
define biochemical purification
you harvest bac -> take supernatant -> separate into fraction and looks for fraction that causes cell to be sick in culture -> once identified, look at gene fraction
28
what is the difference between a library screen and library selection
screen: looking at every cell to see if it has property at interest
selection: only thing that survives is cell with property of interest
29
define reporter fusion
looking at genes expressed in different conditions
30
transcriptional vs translations reporter fusions
transcriptional has gene of interest with reporter gene while translation has both of them connected/merged
31
what is the purpose for reporter fusions?
detection (is expression happening), visualization, localization, purified, selection
32
define transposon mutagenesis and screen
uses transposons to randomly insert mutations into a genome
*can identify genes needed
33
define tn-seq
creates sequencing of wild type and mutant gene
- can compare population in vitro and in vivo and see who lives since you are finding genes important for virulence
34
define rna-seq
exract mRNA from host cell and turn into cDNA -> fragment and prep for sequence and see hits for genes aka which bac rna genes are upregulated
you are looking at which genes are expressed during infection
35
define comparative genomics
looking at genes present in pathogen and non pathogen
*genes just found in pathogen are important for virulence*
36
define protein microarray
take infected animals -> extract proteins and bind to chip -> see which proteins are present
**chip has antibodies that bind to bac proteins**
37
define in vivo antigen technology
identifies pathogen antigens expressed only during human infection
look at serum with ab reactive agaisint in vivo and make genomic expression library -> reaction clones get dna sequence cloned and genes are identified as in vivo induced antigens
38
what is a toll like receptor
recognizes signals on microbe (ex.LPS)
39
define phagolysosome
breaks up pathogen
40
cytokine v. chemokine
cytokine is secreted by phagocytes that exposed to BAC and chemokine stimulates chemotaxis and migration of immune cells to site of infection
41
what proteins help cytotoxic t-cell?
perforin - makes hole and causes cell lysis
42
why is the human microbiota a good thing?
normal bac take up space and so it makes it harder for foreign bac to come in
43
how can antibody inactive antigen?
neutralization (coats bac)
agglutination (clumps around)
complement (hole)
precipitation
44
define biofilm
where bac stick together and antibiotics cant get inside as easily as surface bac
45
define motility and chemotaxis
used by flagella as they run tumble and run
ex of h.pylori raising pH and so mucus become liquid and bac can enter easily
46
define siderophore
bac make this to sequester iron from host cell
47
siderophore is an example of?
nutritional immunity
48
define adherence
variation of pili stick onto host and non-pili adhesins exist such as afimbral adhesion
49
how does enteropathogenic ecoli get into host cell?
induces formation of pedestals on host cell surface
so it ejects tiR protein on host cell and epec expresses intimin and binds to TiR
50
capsule prevents _______
phagocytosis
51
define host mimicry
immune system doesnt recognize bac and example of this is campylobacter and it makes gm1 on surface which is a sugar that coats nerve cells
52
define resistance to antimicrobial peptides
bac will change cell wall to combat antimicrobials
53
how do you measure resistance of bacterial to a antimicrobial?
minimum inhibitory concentration (mic) aka whats the lowest concentration of antibiotics that inhibits bac growth
54
higher mic means?
bac is more resistant
55
what are some hide and seek examples?
replicates intracellularly in vacuole
induces unexpected phagocytosis
never goes outside
infection through basal layer
set up of ibc
formation around bac
56
lytic cycle v. lysogenic cycle
how phages spread toxins!
lytic = incorporate toxin phage dna seperate from bac dna and bac makes copies and phage makes cell to lyse so more get released
lysogenic cycle = phage dna in incorporated with bac chromosome aka prophage and bac replicates (may contain toxin gene)
57
define endotoxin
a nonprotein toxin
in gram + it is lipteichoic acid
in gram - it is the LPS
**in both is the peptidolgycan
58
Lipid ___ determine toxicity in LPS
A
- bac change change lipid a during infection
59
define mycolactone toxins
blocks inflammation and defects healing
60
define superantigen
a protein toxin in which brings mhc and t-cell receptor together without antigen fragment
**causes massive immune response
61
define pore forming toxin
a protein toxin in which toxin binds to receptor on host cell -> oligomerizes it and inserts in membrane and causes pore to form
62
what is botulinum neurotoxin
single chain AB toxin and bac produces toxin. attacks neurons aka causes muscle paralysis
63
what is adp-ribosylating toxin?
class of toxins that modify by adding adp-ribose from an NAD to a host cell protein
64
define AB toxin
ex. dipheria toxins
a(active) and b(binding)
**adp ribosylates blocks ef2, which is what brings in tRNA but now will no longer occur
65
define ab5
ex. cholera toxins - sends chloride to intestines and body reacts by reflux of water
66
define ab7
"A" subunit is a lethal or edema factor
"B" subunit is protective antigen protein
example of anthrax toxin
67
defineAB5 ADP-ribosylating toxin
pertussis toxin
- a subunit adp ribosylates g protein so interferes with signaling and immune cells and increase cAMP
68
what does the SEC protein do?
transport proteins from cytoplasm to periplasm
69
what signal tell SEC to do what it does?
twin arginine translocation system (tat)
70
_______ cuts signal sequence and rest of protein is sent to periplasm
signal peptidase
71
which secretion systems are SEC INDEPDENT?
1,3,4,6
72
which secretion system are SEC DEPENDENT?
2 and 5
73
describe T5SS
goes through SEC -> signal sequence left in membrane -> moves across beta barrel (in outer membrane) and gets cleaved
**not gated
73
describe T2SS
substrate passes through SEC and is now in periplasm -> goes through T2SS and pushes substrate out via pilus structure
**gated
74
describe T1SS
structure spans from cytoplasm to extracellular space
75
describe TYPE3SS
needle tip extends from BAC to HOST CELL MEMBRANE
- tip anchors in host membrane via translocase complex, this then pokes hole and injects protein into host cell
76
what complex helps TYPE3SS anchor onto host membrane?
translocase complex
77
TYPE 3SS has a evolutionary relationship with?
flagella - hook structure also used in translocator pore
78
In TYPE3SS, what tells the needle it is long enough and makes tip complex and translocator pore to form?
tape measure protein
79
effector proteins can have ____?
chaperones which make sure that effector doesnt mess with bacteria
80
For T3SS, tow things are necessary/not necessary
adhesions to host cell is necessary!
internalization of bac not necessary!
81
how does cytochalasin d tell you about internalization?
it inhibits actin polymerization so if secretion happens with cyto D present then you do not need internalization
82
describe T4SS
related to pilus in conjugation
**can move DNA and PROTEIN**
can be used to make another BAC sick
83
describe T6SS
pokes hole in host cell membrane via needle apparatus
**used by bac to kill other bac**
84
TYPE6SS is evolutionary compared to?
how phage inject DNA -- related to phage tail
85
define CMT
cytotoxic mediated translocation
86
give example of CMT
have SEC transport -> transports SPN and SLO (need secretion of both) so cytotoxic can be transported
87
cytotoxin-mediated translocation only happens if...
there is tight adherence between bac and host cell
88
what prevents SPN from being active in BAC?
immunity factor
89
define amoeba plaque assay
spread bac on plate & then spread amoeba on plate -> if amoeba eat bac and live it is a avirulent strain
if virulent -> no plaques because bac killed amoeba
90
define fractionation
host cells exposed to bac and looking at 2 effector proteins -> run fraction to see which proteins are in which part of cell
91
define digitonin
detergent that solubilizes plasma membrane but not nuclear membrane
92
define translocation assay
FRET!
- using 2 fluorescent proteins you then see the overlap between both and seeing how they are moving across the cell membrane since you are testing for protein protein interactions
