LSCI 230 Final Flashcards
1
Q
Name 3 criteria of classification of phenetic taxonomy
A
- All characteristics should be considered of equal importance (unbiased).
- Organisms should be grouped based on overall similarity.
– Classification should be based on as many features as possible.
2
Q
How are similarities between pairs of microorganisms calculated and expressed?
A
similarity coefficient (S)
Jaccard coefficient (SJ)
3
Q
what is a mutation?
A
change in genome
4
Q
Most genetic changes are?
A
neutral
5
Q
What is the role of adaptive mutations?
A
improve fitness of an organism, increasing survival in its
environment.
6
Q
WHat is the role of silent mutations?
A
may be beneficial in other environments allowing the microorganism to
colonize new niches.
7
Q
Are deleterious mutations lost?
A
yes
8
Q
What does the accumulation of mutations lead to?
A
speciation
9
Q
What did Carl Woese do ?
A
– Sequencing of the small subunit rRNA (SSU rRNA): 16S rRNA in prokaryotes, 18S rRNA in eukaryotes.– Established the presence of three domains of life:
Bacteria, Archaea, and Eukarya– Provided a unified phylogenetic framework for Bacteria
10
Q
What does comparative r RNA sequencing involve?
A
– Amplification of the gene encoding SSU rRNA
– Sequencing of the amplified gene
– Analysis of sequence in reference to other sequences
11
Q
What is rRNA sequencing used for?
A
infer the phylogeny of prokaryotes and other microorganisms.
12
Q
What is the evolutionary relationship between two organisms directly correlated to?
A
the number of mutations in each one
13
Q
Are two organisms closely related or not if there are few differences?
A
closely related
14
Q
NAme 2 charcateristic of streptomyces
A
hyphal growth
produce spores at tip of elevated sprorophore
15
Q
NAme a filamentous actinobacteria?
A
streptomyces
16
Q
Name a predatory bacteria
A
bdellovibrio
17
Q
Where does bdellovibrio acquire nutrients from?
A
host cells
18
Q
which kind of bacteria does bdellovibrio infect?
A
GRAM NAGATIVE
19
Q
Name a stalked bacteria?
A
caulobacter
20
Q
Name the 2 types of caulobacter
A
stalked mother cell
flagellated daughter cell
21
Q
What does the stalk of caulobacter secrete
A
stickiest substance known
22
Q
Name an obligate intracellular bacteria
A
chlamydia
23
Q
What is an elementary body of chlamydia?
A
infectious, releases from host cell
24
Q
What is a reticulate body of chlamydia
A
intracellular, active growth
25
what methods does the polyphasic approach to taxonomy use?
phylogenetic analysis
phenotypic analysis
Genotypic analysis
26
What is MLST?
several different “housekeeping genes” from a species are sequenced and aligned to the respective sequences of other individuals of the same species
27
WHat ways can unknown microorganisms be identified?
morphology
– Biochemical properties
– 16S rRNA sequencing.
– MLST
– Whole genome sequencing
- Dichotomous key
-serotyping
28
Name 3 methods to test for phenotypes?
MacConkey agar (lactose
fermentation)
Catalase test on a colony
API strips
29
what is serotyping?
Based on the binding of specific antibody to surface structure
30
What are antibodies
molecules of the immune system that recognize and bind to
molecule on the surface of a microorganism or to secreted proteins.
31
What is a positive reaction of serotyping?
agglutination
32
WHat is used to infer the phylogeny of eukaryotes?
Sequencing of 18S rRNA genes
33
True or false:Relationship between 18S rRNA genes is weaker for eukaryotes than 16S rRNA
genes is for prokaryotes
True
34
WHat is another name for red algae?
rhodophytes
35
What do red algae get the red color from?
phycoerythrin
36
WHta are green algae also called?
chlorophytes
37
ARe green algae uni or milticellular?
Can be both
38
Are green algae sexual or asexual?
both
39
Which kind of algae grow in popous rocks?
endolithic algae
40
What do amitochondriate eukaryotes have instead of mitochondria?
mitosome
hydrogenosome
41
WHat is a mitosome?
that does not have enzymes of the TCA cycle and does not have a respiratory chain.
42
WHat is a hydrogenosome?
carries out the oxidation
of pyruvate to H2, CO2 and acetate.
only in fermenters
43
What are cysts?
like endospore in prokaryotes
Survive long periods of starvation and/or desiccation.
* Survive infection by prokaryotes.
44
What are common characteristics to diplomonads and parabasalids
* Unicellular
* Flagellated
* Lacks chloroplasts
* Live in anoxic habitats
45
Give 2 characteristics of diplomonads
– Have two nuclei of equal size
– Have mitosomes
46
NAme 3 characteristics of parabasalids
parabasal body
hydrogenosome
live in intestinal and urogenital tract of animals
47
name a parabasalid?
trichomonas vaginalis
48
can trichomonas vaginalis form cysts?
no
49
what are euglenozoans?
unicellular flagellated eukaryotes
50
What does euglenozoans include
kinetoplastids and euglena
51
What is a kinetoplast?
a mass of DNA present in their single, large mitochondrion.
52
NAme a kinetoplastid that causes african sleeping sickness
Trypanosoma brucei
53
NAme 3 charcateristics of euglena
– Nonpathogenic and phototrophic.
– Contain chloroplasts, can exist as heterotrophs; will lose its chloroplast if incubated in the dark for a long time.
– Can feed on bacteria by phagocytosis (mixotroph).
54
NAme 3 kinds of alveolates?
ciliates dinoflagellates apicomplexans
55
How do ciliates reproduce?
sexually through conjugation
56
True or false: ciliates have 2 nuclei
true micro and macronucleus
57
name the 2 kinds of flagella of dinoflagellates?
Transverse flagellum
– Longitudinal flagellum
58
True or false: dinoflagellates can release toxins
true
59
what are apicoplasts?
degenerate chloroplasts that lack pigments and phototrophic
capacity, but still carry many anabolic pathways.
60
True or false: apicomplexans are obligate parasites of animals?
true
61
name 3 kinds of stramenopiles?
Oomycetes, diatoms, golden algae
62
name a characteristic of oomycetes?
Cell walls are made of cellulose
63
WHat is another name for golden algae?
chrysophytes
64
What is a pigment is golden agae?
carotenoid: Fucoxanthin
65
name a characteristic of diatoms?
Frustules: cell walls made of silica
66
How are cercozoans and radiolarians distinguished from other protists?
threadlike pseudopodia
67
Name a characteristic of cercozoans
Tests are made from organic materials
68
Name a characteristis of Radiolarians?
Tests are made of silica
69
NAme 3 types of amoebozoa
gymnamoebas, entamoebas, and slime molds
70
What are gymnamoebas and entamoebas?
* Gymnamoebas: Free-living, inhabit soil
and aquatic environments
* Entamoebas: Parasites of vertebrates
and invertebrates (Ex: Entamoeba
histolytica)
71
name 2 types of slime molds?
plasmodial slime mold
cellular slime mold
72
Describe the life cycle of plasmodial slime molds
Have vegetative forms that are
masses of protoplasm of
indefinite size and shape
(plasmodium), that contain
multiple nuclei.
* From the plasmodium, a
sporangium can form,
containing multiple haploid
spores (dormant, resistant, for
dispersal).
* The spores germinate, yielding
a swarmer cell (flagellated or
amoeboid). The fusion of two
swarmer cells regenerates the
diploid plasmodium.
73
describe the life cycle of cellular slime molds?
Cellular slime molds:
vegetative forms composed
of single amoebae
(haploid).
* Aggregate as a
pseudoplasmodium (slug)
that can move as a single
unit (cells do not fuse).
* Fruiting body is formed,
cells differentiate into
spores.
* May form diploid
macrocysts (diploid) that
undergo meiosis to form
new amoebae (haploid):
sexual reproduction.
74
name 2 types of hyphal network
– Coenocytic: cytoplasm and nuclei are not subdivided into cells.
– Septate: nuclei are separated by cross wall
75
What are fungal cell walls made of?
chitin
76
name 3 forms of asexual reproduction of fungi?
1. Growth and spread of hyphal filaments
2. Simple cell division (budding yeast)
3. Asexual production of spores
77
What are asexual spores of fungi called
conidia
78
describe sexual reproduction in fungi?
Sexual spores can originate
from the fusion of two
haploid cells to form a
diploid cell that then,
undergo meiosis to produce
haploid spores (ascospores,
basidiospores, zygospores)
– Spores are resistant to
drying, heating, freezing,
chemicals
79
WHta are the 2 mating types of Saccharomyces cerevisiae
a and alpha
80
Lichens origin from the association of which two organisms?
fungus and phototroph
81
name 2 types of mycorrhizae
Ectomycorrhizae: form a sheath around the plant root but does not penetrate it.
– Endomycorrhizae: the fungal hyphae is embedded in the plant root
82
what is pathogenesis?
Many fungal plant pathogens form
specialized hyphae – haustoria – to
penetrate the plant cells and
consume the cytoplasm
83
WHta is a virion?
inert infectious particles
84
what different nucleic acids can be found in virus?
– DNA virus
– RNA virus
– Both can have either single stranded or double stranded genomes
85
WHat is capsid?
protein coat around the nucleic
acid
86
What is nucleocapsid?
nucleic acid + protein coat
87
WHat is capsomere?
protein subunit that makes up
the capsid.
88
What is enveloppe?
lipid-containing layer with
embedded proteins; in animal viruses, this
envelope originates from the cytoplasmic
membrane of the host cells.
89
What is the most common polyhedral virus shape?
icosahedron
90
What are viroids?
closed circles of single-stranded RNA
91
How are viroids transmitted?
insects
92
What are prions
misfolded protein
93
How do Prions work?
The misfolded prion proteins (PrPSc) induces misfolding of the PrPC protein. The
prion protein does not replicate, it induces accumulation of misfolded PrPSc
proteins, which kills the cell. The PrPC protein is primarily found in neurons.
94
Virus families end in?
viridae
95
virus genus ends in ?
virus
96
how are viruses classified?
– Nature of the host (animal, plant, bacteria, etc.). Ex.: bacteriophages infect bacteria.
– Type of disease caused (enteric, leukemia, pneumonia). Ex. Murine leukemia virus
(MLV).
– Life cycle (pathways of nucleic acid replication and transcription).
– Naked or enveloped
– Type of nucleic acids and strandedness (+ strand: same as mRNA)
97
What is the baltimore classification scheme?
Classification is based on the type of genome
98
WHat is + configuration?
same strand than
mRNA (can be translated directly)
99
what is - configuration?
: complementary
to mRNA (needs to be transcribed
into plus strand before it can be
translated).
100
What is viral RNA dependant RNA polymerase supplied by?
virus
101
how do enveloped viruses enter host cell
membrane fusion
102
How do most envelopped viruses of eukaryotes enter ?
endocytosis (viropexis)
103
What are the 5 steps of life cycle of virus?
attachment
penetration
biosynthesis
maturation
release
104
What is the latent period?
time
necessary for the host cells to
replicate the viral genome and to
synthesize the viral components.
105
What is release period?
Virions are detected outside
cell.
106
What is burst size?
number of virions
released
107
WHat are virulent phages?
infection of host cells
always leads to replication resulting in host cell lysis (lytic pathway)
108
what are the two opttions of temperate phages?
1) lytic pathway or 2) lysogenic pathway
109
where is lambda genome integrated?
attλ site
110
What is a prophage?
phage genome within the host cell chromosome.
111
What is a lysogen?
bacterium that contains a prophage.
112
Where is dna virus replicated?
nucleus
113
Where is rna virus replicated?
cytoplasm
114
Name an example of + rna virus?
poliovirus and hep A
115
NAme an example of - strand virus?
measles rabies influenza
116
True of false dsrna can be directly translated?
false,First, a plus-strand RNA must be
synthetized by a viral-encoded RNA-dependent RNA polymerase using the minus
strand as the template
117
NAme an example of retrovirus
HIV
118
What is a provirus?
integrated viral DNA. Contrary to
the lambda prophage, the provirus cannot
excise from the host genome.
119
What are 4 mechanisms of tumor producing viruses?
1. Transduction.
2. Insertion of a strong promoter.
3. Inactivation of a tumor suppressor gene.
4. Expression of a viral protein that induces transformation (DNA virus)
120
What are used to treat viruses?
nucleoside analogs
121
What do nucleoside analogs do?
block reverse transcriptase and
production of viral DNA (RNA viruses)
122
What do protease inhibitors do?
inhibit the processing of large viral proteins into individual components (e.g. Paxlovid)
123
What is an ecosystem?
The sum of all organisms and abiotic factors in a particular environment
124
What is a habitat?
Portion of an ecosystem where a community could reside
125
True or false: an ecosystem contains many habitats
True
126
What is a population?
Group of microorganisms of the same species residing in the same place at the same time
127
What is a community?
A group of populations
128
What are the two ways in which a ecosystem is expressed?
Species richness
Species abundance
129
What is species richness?
Total number of species present
130
What is species abundance?
Proportion of each species in an ecosystem
131
What is a guild?
Metabolically related microbial populations
132
What is a niche?
Habitat shared by a guild
133
What does the growth of microbes depend on?
Resources and growth conditions
134
What defines the niche for each microbe?
Type and quantity of resources and physiochemical conditions
135
What is a prime niche?
Niche in which organism is most successful
136
What is a micro environment?
Immediate surroundings of a microbial cell
137
Are growth rates higher in a lab or in nature?
Lab
138
Name 3 types of relationships?
Parasitism
Mutualism
Commensalism
139
What is biogeochemistry?
The study of biologically mediates chemical transformations
140
What are the two broad groups of soil?
Organic soil
Mineral soil
141
What is mineral soil?
Derived from Rick weathering and other inorganic materials
142
What is organic soil?
Derived from sedimentation in bogs and marshes
143
What is soil composed of?
Inorganic mineral matter
Organic matter
Air and water
Living organisms
144
Name the 5 soil horizons
Organic horizon
Surface horizon
Subsoil
Substratum
Bedrock
145
What is organic horizon made of?
Undecomposed organic material
146
What is surface horizon made of?
Organic material, high microbial activity
147
What is subsoil made of?
Humus, minerals, lower microbial activity
148
What is humus?
Dead plant material that is resistant to decomposition
149
What is the substratum and the bedrock made of?
Rich in minerals, poor in organic materials, low microbial activity
150
Which drains faster sand silt or clay?
Sand
151
What are bacteria and archaea largely responsible for in soil?
Production of humus
Release of minerals from soil particles
Cycling of nutrients
Nitrogen fixation
152
What is the rhizosphere?
Soil that surrounds plant roots and receive plant secretions
153
What are mycorrhizae?
Association of fungi with plant roots
154
What is nitrogen fixation reaction catalyze by?
Nitrogenase complex
155
How many electrons and atp are required for nitrogen fixation?
16atp
8 electrons
156
How many electrons are lost as H2 in nitrogen fixation?
2
157
What is dinitrogenase reductase inhibited by?
Presence of oxygen
158
What do free living nitrogen fixers produce that can be used by plants?
Ammonia
159
Is clostridium an anaerobe or an aerobe?
Strict anaerobe
160
Is azotobacter an anaerobe or an aerobe?
Aerobe
161
True or false: Cyanobacteria can fix nitrogen
True
162
Where does nitrogen fixation occur in Cyanobacteria?
Heterocysts
163
Which photo system does cyanobacteria heterocyst lack?
PS2
164
What do regular Cyanobacteria cells provide the heterocyst?
Sucrose(carbohydrate)
165
What do heterocysts produce with the sucrose from normal cells?
NADPH via Penrose phosphate pathway
166
What do heterocysts produce with NH3?
Glutamine (2N)and glutamate(1N)
167
What causes the formation of root nodules?
Colonization of root by nitrogen fixing bacteria
168
How is a root nodule formed?
Plant secretes chemical to attract nitrogen fixers
Attachment of bacteria to root hairs
Excretion of nod factors by bacteria
Bacteria travel down infection thread
Formation of bacteroid state within plant cell
169
What are oxygen levels in nodule controlled by?
Leghemoglobin
170
True or false bacteria in bacteroid can be shed in environment
False
171
What do anaerobic conditions promote?
Sulfur and sulfate reduction
172
What are primary producers?
Organisms that serve as a food source for chemoheterotrophs
173
What is photic zone?
Zone where light penetrates
174
Which photic zone is bigger in open ocean or coastal water?
Open ocean
175
Organisms found in marine environments are what kind of tolerant?
Halotolerant
176
What is the pelagic zone?
Deep sea
177
Below 100m does the temperature fluctuate?
No
178
Is primary productivity un the pelagic zone elevated?
No very low ( oligotrophic)
179
In the open ocean, where does the bulk of primary productivity come from?
Prochlorophytes
180
What are 2 types of primary producers in coastal waters?
Algae and Cyanobacteria
181
Why is productivity higher in coastal waters?
Pollution
182
Who degrade organic matter between 300 and 1000m?
Chemoherterotrophes, psychrophiles
183
True or false: below 1000m carbon is very scarce, oligotrophic environment
True
184
What are hydrothermal vents a source of?
Heat, nutrients, electron acceptors
185
True or false: lakes have good mixing and aeration
False
186
True or false: rivers have good mixing/aeration
True
187
In oligotrophic lakes, is primary productivity high or low?
Low
188
In oligotrophic lakes, is the lake aerobic or anaerobic?
Aerobic
189
In a eutrophic lake, is primary production high or low?
High
190
Is a eutrophic lake aerobic or anaerobic?
Anaerobic
191
Bottom sediments of eutrophic lakes support growth of which kinds of microorganisms?
Denitrifyers, methanogens, sulfate reducers
192
What is epilimnion?
Warm upper layer
193
What is hypolimnion?
Colder, bottom layer
194
When does mixing happen in lakes in temperate climates?
Spring and fall only
195
What I’d the pollution of freshwater?
Deliberate discharge of effluents into a waterway
196
What is sewage rich in?
Organic matter and pathogens
197
What is biochemical oxygen demand?
Measure of extent of pollution by organic matter
198
What is a biofilm?
Microbial cells embedded inside an extra cellular matrix
199
True or false: cells in the biofilm are more resistant than planktonic cells?
True
200
Where do most waterborne pathogens grow?
In intestinal tract
201
What are sources of infection of waterborne pathogens.
Potable water
Recreational water
202
Give 3 examples of waterborne pathogens
Salmonella typhi
Vibrio cholerae
Campylobacter
203
Give 3 examples of waterborne pathogenic Protozoa
Entamoeba histolytica
Giardia lamblia
Cryptosporidium parvum
204
True or false: cysts of c parvum are effectively removed by the filtration process?
False
205
What are most waterborne pathogens associated with?
Fecal matter
206
What are two indicators of water quality?
Coliforms
Fecal coliforms
207
What is the difference between coliforms and fecal coliforms?
Fecal coliforms grow at higher temp.(44C)
208
True or false the absence of fecal coliforms ensure good water quality?
False
209
How do u test for coliforms?
Membrane filtration
210
What does water treatment aim to do?
Remove pathogens
Improve clarity of water
Remove compounds that give bad taste or smell
Soften water
211
Name the 3 steps of drinking water treatment?
Coagulation, flocculation and sedimentation
Filtration
Disinfection
212
Why do we use chlorine to disinfect water?
Very reactive in water
Kills remaining organisms
Neutralizes chemicals that give bad taste
213
What is residual chlorine?
Chlorine left in water after it leaves the treatment plant
214
True or false ozone is more effective than chlorine in water filtration?
True
215
What does sewage treatment aim to do?
Reduce BOD
Destroy pathogens
216
What is primary treatment?
Sedimentation+ flocculation produces primary sludge which is dried and incinerated
217
How much BOD does primary treatment remove?
25-40%
218
Name 2 types of secondary treatment?
Trickling filter
Activated sludge
219
What is a trickling filter?
Liquid from primary treatment sprayed on bedrock with biofilm
220
What is activated sludge?
Air is blown through the liquid from primary treatment and slime forming bacteria will form activated sludge that oxidize organic matter
221
What kind of methods does tertiary treatment of water use?
Biological treatment
Flocculation
Filtration
Chlorination or ozonation
222
What is a septic tank?
Settling of the material and minimal sludge digestion
223
True or false septic tanks require periodic emptying
True
224
True or false: commensals colonize the body without causing infection
True
225
In what ways can commensals be beneficial to humans?
Provide host with witamins and metabolic pathways
Provide protection against new incoming microbial populations
Teach immune system
226
True or false:some commensals can become pathogenic under specific conditions
True
227
In animals where are the majority of microorganisms found?
Gastrointestinal tract
228
Can animals digest cellulose?
No
229
What are two digestive strategies evolved in herbivorous animals?
Foregut fermentation
Hindgut fermentation
230
How many stomachs do cows have?
4
231
What is the foregut fermentation chamber in ruminants?
Rumen
232
What is the stomach of ruminants called?
Abomasum
233
What does the mass of microbial cells subjected to digestion produce?
Amino acids and vitamins
234
What is cellulose hydrolyzed to?
Soluble sugars (glucose)
235
What are sugars fermented to in the rumen?
Volatile fatty acids, co2 and H2
236
What do the cellulosomes in ruminococcus do?
Pulls cellulose to cellulase
237
What do methanogens produce?
Methane
238
True or false methanogens are strict anaerobes
True
239
True or false the acetate used by methanogens is available to host.
False
240
What does monensin in do?
Inhibit methanogenesis
241
Where does fermentation take blade in non ruminant herbivores?
Caecum
242
True or false, the microbial mass on cellulose is not digested in non ruminant herbivores.
True
243
What is the epidermis composed of?
Inner layer of living cells and outer layer of dead cells
244
What do sweat glands secrete?
Salt water with proteins, lipids and sugars
245
True or false skin is generally acid.
True
246
Are skin ducts colonized by gram positive or gram negative bacteria?
Positive
247
What is bacteriocin
Secreted by normal micro biome, kills competitors and protects against harmful bacteria
248
Name one anaerobe that inhabits hair canals?
Propinobacterium acnes
249
What do teeth consist of?
Mineral matrices(enamel) surrounding living tissue dentin and pulp)
250
What microorganisms cause cavities?
S. MUTANS
251
what demineralizes the tooth enamel?
Lactic acid
252
What type of microorganisms grow in the stomach
Acidophiles
253
What prevents microorganisms from colonizing the GI tract?
The acidity of the stomach and the duodenum
254
What kind of organisms live in the GI tract?
Strict anaerobes or facultative anaerobes
255
What do sulfate producers ferment in the human colon?
Cysteine and methionine
256
True or false: the lower respiratory tract is free of microorganisms
True
257
True or false the genitouranary tract is free of microorganisms
True
258
What do the microorganisms in the vaginal tract degrade and produce?
Degrade glycogen to produce lactic acid
259
what is a pathogen?
microbial parasites that are able to cause infection
260
what is an infection?
situation in which a microorganism is established and growing in a host,
causing damage.
261
what is a disease?
damage or injury to the host that impairs host function
262
what is pathogenicity?
ability of a parasite to inflict damage to host
263
what is virulence?
measure of pathogenicity
264
what is an opportunistic pathogen?
causes disease only in the absence of normal host
resistance.
265
NAME the 5 steps of infection
1. Exposure
2. Adherence
3. Invasion
4. Colonization of tissues and growth
266
what is damage to host determined by
invasiveness
toxigenicity
267
what is invasiveness
ability to become established in host and spread to tissues
268
what is toxigenicity?
the capacity of the microorganism to produce substances
known as toxins that damage specific
tissues of the host
269
name 3 types of virulence factors?
adhesins
capsules
invasins
270
what is the role of adhesins?
promote specific attachment to host cell surface
271
What do fimbriae/ pili mediate
loose attachement
272
What does afrimbrial adhesins mediate
close attachment
273
What is the role of the capsule
Prevents the pathogen from being
destroyed by host immune cells
(phagocytes).
* Also mediates attachment to host cells
and to other bacteria.
274
what does hyaluronidase do?
degrades hyaluronic acid( hyaluronan) that keeps host cells together
275
What does collagenase do?
degrades collagen present in connective tissues
276
what does lecithinase do?
degrades lecithin (phosphatidylcholine) in cell membrane – causes the
lysis of red blood cells and destroys tissue cells.
277
what causes gas gangrene?
clostridium perfringens
278
what does Clostridium perfringens use to destroy ecm?
Uses lecithinase to lyse host cells, collagenase and hyaluronidase
279
what are hemolysins?
enzymes that Cause lysis of red blood cells
and a variety of cell types.
280
what are invasins?
Surface proteins, or injected proteins, that allow microorganisms to enter cells (invade host cell).
281
what properties need to be modified to permit growth in ost cells?
* Block phagosome maturation (block digestion)
* Increase size of the vacuole
* Acquire nutrients
* Block detection of intracellular infection and response (host defense)
282
What does T3SS do?
forms a channel through the
bacterial cytoplasmic membrane, the
periplasm, the outer membrane, and
the host cell membrane so bacterial
proteins can be injected
cell cytosol
283
what is the function of t3ss and t4ss?
– Invasion of host cells.
– Block phagosome maturation.
– Take control of host cells
284
What is t4ss?
similar to T3SS but absence of
needle-like structure.
* Also called “injectisomes”
285
what are infectious diseases?
result from the pathogen’s growth
286
what are intoxications?
result from the presence of a specific toxin.
287
what are the two types of toxins?
exotoxins and endotoxins
288
what is an exotoxin
secreted into the surrounding as the bacterial pathogen grows
289
what is endotoxins
part of bacterial pathogen
290
ture or false: exotoxins are usually heat-labile
true
291
which 2 subunits are AB toxins made of?
– enzymatic subunit (A)– binding/cell entry subunit (B)
292
What does the A subunit of AB toins do ?
modifies a target
inside the host cell leading to
damage to the host.
293
What does the B subunit do in AB toxins?
binds to specific cell
receptors providing tissue/cell
type specificity
294
True or false: endotoxins are heat stable
true
295
true or false: endotoxins are very effective immmune system activators?
true
296
What does it mean that exotoxins are antigenic?
stimulates the host defense systems to produce
antibodies that can neutralize the toxin.
297
how are vaccines against exotoxins made
turned into toxoids first then made into vaccines
298
what are alveolates characterized by?
the presence of alveoli,
which are sacs underneath
the cytoplasmic membrane
299
What is the function of alveoli?
– May function to help cells
maintain osmotic balance
– In Paramecium:
contractile vacuole.
