CMMB 343 Flashcards
1
Q
What it the largest known prokaryote?
A
Thiomargarita
2
Q
Who was the father of microbiology?
A
Anton van Leeuwenhoek
3
Q
What is bioremediation?
A
Using bacteria to clean up toxic compounds
4
Q
What are the two classifications for carbon acquisition?
A
Heterotrophs - use multiple compounds as a carbon source
Autotrophs - use CO2 as the main source (usually primary producers)
5
Q
What are the three ways in which organisms gain their energy?
A
Chemolithotrophy
Chemoorganotrophy
Phototrophy
6
Q
In chemolithotrophs what do they use as an energy source?
A
Inorganic chemicals like H, H2S, Fe, NH4 etc
7
Q
In chemoorganotrophs what do they use as an energy source?
A
Organic chemicals like glucose, acetate etc.
8
Q
Who was the father of taxonomy?
A
Carolus Linnaeus
9
Q
What did Ernst Heckel’ propose the kingdom tree should look like?
A
- Would have three groups
- Is not based on empirical data
- The organisms always evolve to a higher more complex state
10
Q
Who suggested the use of DNA to form the tree?
A
Carl Woese
11
Q
What were 3 reasons why the 16S rRNA was a good fit for testing the tree of life?
A
- it is universal to all organisms
- does not undergo lateral transfer between different species
- mutates very slowly
12
Q
Which domain is most closely related to archaea?
A
Eukarya
13
Q
What species is the largest group of bacteria?
A
Proteobacteria
14
Q
What are the two phylum of Archaea?
A
- Crenarchaeota
- Eurarchaeota
15
Q
How to identify the Crenarchaeota
A
- usually very thermophilic (116C)
- many are lithotrophic on S or H
16
Q
How to identify the Euryarchaeota
A
- includes the methanogens and the extreme halophiles
17
Q
How do E. coli obtain their energy?
A
Chemoorganotrophic
18
Q
What are three common soil bacteria in Proteobacteria?
A
- Pseudomonas
- Azotobacter
- Rhizobium
19
Q
What is a photoautotrophic proteobacteria?
A
Purple sulfur bacterium (chromatium).
20
Q
Chromatium do not use photosynthesis. What do they use instead?
A
They don’t use photosynthesis since they do not use O2 as a final electron acceptor they use H2S instead.
21
Q
Which species is dominant in microbial mats?
A
Green nonsulfur bacteria (Chloroflexus)
22
Q
The gram positive group has 5 different classifications under it. What are they?
A
- spore formers (Bacillus, Clostridium)
- antibiotic producing (Streptomyces)
- lactic acid producers (Lactobacillus and Streptococcus)
- mycoplasmas (lack a cell wall)
- plant symbionts
23
Q
Classify Firmicutes.
A
Gram positive endospore formers
24
Q
What are actinobacteria?
A
Gram positive that produce antibiotics
25
Plantomycetes and Spirochaetes have unique morphologies. What are they?
Plantomycetes - stalked bacteria
| Spirochaetes - helical bacteria
26
What is special about Deinococcus?
They have unusual cell walls and are highly resistant to radiation.
27
What term did Ferdinand Cohn coin?
Bacteria meaning small rod or staff and grouped the organisms based on shape.
28
What is DNA hybridization?
Mixing of two genomes to compare similarities
29
How much must the DNA match to be considered the same species through hybridization?
More that 70% must match
30
When comparing the 16S rRNA, how different do they need to be to be considered a new species?
1-3% different
31
Which do you test first; DNA hybrid or 16S rRNA?
rRNA
32
What does ICSP stand for?
International Committee on Systematics of prokaryotes
33
Who regulates the naming of bacteria?
International Code of Nomenclature of Bacteria
34
What are extremophiles?
Bacteria that prefer conditions outside of the normal
35
What constitutes the largest group of extremophiles?
The archaea
36
Define psychro-
cold temperatures
37
Define thermo-
high temperatures
38
Define meso-
middle
39
Define alkali-
high pH
40
Define piezo-
high pressure
41
Define xero-
dry
42
Define radio-
radiation
43
define -troph
average or some ability
44
define facultative
sometimes they can/can't
45
Give examples of thermophilic habitats
- deserts
- compost, decaying matter
- deep biosphere
- geothermal systems
46
What are three ways methods for surviving high temperatures?
1- strong bonds to stabilize proteins to prevent denaturation
2- decrease membrane fluidity
3- increase RNA stability by increasing GC content
47
How do bacteria prevent proteins from denaturing?
- certain amino acids provide more heat tolerant folds
- more ionic bonds between basic and acidic amino acids
- production of solutes
48
Name a sulfide/sulfur oxidiser
Thiothrix
49
Name three archaea that are hyperthermophile (>80C) that are also hydrogen or sulfur-metabolisers
- Pyrodictium
- Pyrolobus
- Sulfolobus
50
What do methanogens produce?
Methane gas
51
What is the range of a neutrophile?
6-8
52
Who is the champion acidophile?
Ferroplasma acidarmanus at a pH of 0
53
What is the problem with acidophile/alkylophile?
The membrane must be impermeable to protons and so it is difficult to maintain a proton motive force (some use sodium)
54
Which bacteria is highly radiation resistant?
Deinococcus radiodurans 1000x more than humans
55
How does Deinococcus radiodurans protect their chromosome?
- tight coils
- repair damaged DNA
- 4 copies of chromosomes but only 2 are active at a time
56
What are endospores?
Differentiated cells that are highly resistant. Only found in some gram positive cells
57
What does an endospore germinate into?
a vegetative cell
58
What are clorosomes?
They are light antennae that allow the cell to grow under low light
59
What are two bacteria that use clorosomes?
Chloroflexi and Chlorobi
60
What are carboxysomes?
they are special structures that house calvin cycle enzymes like RubisCO-
61
What cells are purple and what cells are red in a gram stain?
```
Purple= positive
Red= negative
```
62
What are the three components of a gram positive membrane?
- cytoplasmic membrane
- peptidoglycan
- teichoic acids
63
What are the four components of the gram negative bacteria?
- cytoplasmic membrane
- peptidoglycan
- periplasm
- outer membrane
64
What is the cytoplasmic membrane consist of?
Phospholipid bilayer
65
What makes up the outer membrane in gram negative bacteria?
- lipopolysaccharide
| - protein
66
What are used to strengthen the cytoplasmic membrane?
- sterols
- hopanoids
- saturated
67
What are 4 roles of membrane proteins?
- transport
- environmental sensing (signal transduction, chemotaxis)
- electron transport
- membrane and cell wall assembly
68
What is peptidoglycan made of?
N-acetylglucosamine and N-acetylmuamic acid. M binds to another M through glycosidic bonds. M and G alternate.
69
What are two agents that break down peptidoglycan?
Lysozyme - tears in egg white
| Penicillin
70
How does lysozyme break down peptidoglycan?
Hydrolyses peptidoglycan
71
How does penicillin break down peptidoglycan?
Inhibits cross linking of the glycan strands. (inhibits transpeptidation)
72
What is the function of teichoic acid in gram positive bacteria?
- maintain porosity of cell wall
- anchor cell wall to cell membrane
- cell shape
- capture cations
- regulate cell wall turnover
73
What does growth mean?
An increase in the number of cells
74
What is binary fission?
Cell elongation
75
what is generation time?
time required for a population of microbial cells to double
76
What allows a cell to divide?
FtsZ - Filamentous Temperature Sensitive
77
Who has FtsZ?
All bacteria
78
How does FtsZ work?
Creates a ring (Z-ring) in a GTP dependent maner and then constricts
79
What connects the FtsZ ring to the cytoplasmic membrane?
ZipA
80
What does FtsA do?
Helps connect FtsZ to the membrane and recruits other proteins related to actin
81
What does FtsK do?
Mediates the separation of chromosomes to daughter cells
82
What is MreB?
This determines the shape of the cell. Not found in coccus cells
83
How does MreB work?
Forms spiral bands, where the bands meet the membrane they stimulate growth
84
What are autolysins?
Hydrolyze the M G glycosidic bonds of peptidoglycan backbone
85
What does transpeptidation do?
Forms the peptide cross links between M residues
86
What are the 4 growth phases?
1 lag
2 exponential
3 stationary
4 death
87
What is a chemostat?
an open, continuous flow system where growth rate is controlled by the availability of a single nutrient. Allows for constant growth rates
88
What is washout?
Washout is when the dilution rate is greater than the growth rate.
89
How to calculate the dilution rate (D)?
D=F/V
F= flow rate (mL/h)
V= vessel volume (mL)
90
What happens when the dilution rate increases at low dilution rates?
Both cell density and growth rate increase. More nutrients available for reproduction
91
What is metabolism?
The sum total of all chemical reactions that occur in a cell
92
When is deltaG exergonic?
negative
93
What is the deltaG of fumarate to succinate?
-86 kJ
94
What is the deltaG of NO3 to NO2
-163 kJ
95
What is the deltaG of O2 to H2O?
-237 kJ
96
What is substrate level phosphorylation?
Phosphate from organic group added to ADP
97
What is oxidative phosphorylation?
Making of ATP in the electron transport chain.
98
What is the net products made in glycolysis?
2 pyruvate
2 ATP
2 NADH
99
Which is more efficient? production of ethanol or lactate?
Lactate (32% vs 27%)
100
How many ATP are formed during aerobic respiration?
38
101
What does the proton motive force do?
- Drive ATP synthase
- flagellar motor
- transport systems
102
What is denitrification?
Anaerobic respiration that uses nitrate (NO3) as an electron acceptor (NO3->N2)
103
What is good about iron oxidizing?
Acidophilic bacteria useful in concentration of copper ore
104
What is bad about iron oxidizing?
Can release sulfuric acid
105
What is nitrogen fixing?
Nitrogen gas to ammonia
106
What is nitrification?
Ammonia to nitrate (NO3). This happens in two steps
NH4 -> NO2 nitrosification,
NO2 -> NO3 nitrification
107
What is annamox?
The anaerobic oxidation of ammonia to nitrogen gas
108
What are the two bacteria involved in nitrification?
Nitrosomonas and Nitrobacter
109
What bacteria use denitrification?
- bacillus
- paracoccus
- pseudomonas
110
What bacteria use free-living, aerobic nitrogen fixing?
Azobacter
Cyanobacteria
Alcaligenes
111
What bacteria use free-living, anaerobic nitrogen fixing?
Clostridium
Rhodospirillum
Methanococcus
purple and green bacteria
112
What bacteria use annamox?
Brocadia
113
What is the relationship between symbiotic N2 fixers?
- plant produces anaeroic environment
- plant supplies nutrients
- bacteria supply ammonia
114
What enzyme do bacteria use during nitrogen fixing?
Nitrogenase
115
How do azobacter protect the nitrogenase?
respire oxygen at cell surface so the cell remains anaerobic
116
How do cyanobacteria protect nitrogenase?
they fix nitrogen in a heterycyst - a cell in the chain
117
How do clostridium protect nitrogenase?
inhabit oxygen free environment
118
Why is nitrate (NO2) low in soil?
- plants use it readily
| - it is leached out
119
What are methane hydrates?
frozen methane
120
What is the most transferred carbon reservoir?
atmosphere
121
What does the calvin cycle do?
Fixes CO2 to make sugar
122
How much ATP is used to make one sugar?
18
123
What is methanogenesis?
reduction of CO2 to CH4
124
What is syntrophy?
Eating together
125
What is symbiosis?
Living together
126
What do syntrophs do?
- secondary fermentors use acetate from primary fermentors (team up with methanogens)
127
Define species richness
the total number of different species present
128
Define species abundance
the proportion of each species in an ecosystem
129
What are biofilms?
group of bacteria that adhered to a surface and are enclosed in a matrix by the cells that is usually made of polysaccharides.
130
Why would cells form biofilms?
- self defense
- stay in favourable niche
- live in close association
131
What are microbial mats?
Very thick biofilms
132
What are the two main classes of soil?
- Mineral
| - Organic
133
What are the 4 levels of soil in order?
- O horizon
- A horizon
- B horizon
- C horizon
134
What is the defining feature of o horizon?
Undecomposed matter
135
What is the defining feature of a horizon
lots of organic matter and so lots of growth of plants and cells
136
What is the defining feature of b horizon?
subsoil, humus
137
What is the defining feature of c horizon?
soil base any minerals are from rock
138
What is the most abundant marine heterotroph?
Pelagibacter
139
What is an oligotroph?
organism that grows best at low nutrient concentrations
140
What is proteorhodopsin?
allows cells like Pelagibacter to use light energy to drive ATP synthesis
141
What type of energy using bacteria are found in vents?
chemolithotrophic
142
Define parasitic
the microbe benefits at some expense to the host
143
Define pathogenic
the microbe causes a disease in the host
144
Define commensal
the microbe has no discernible impact on the host
145
Define mutualistic
the microbe is beneficial to the host
146
What do fungus and alga or cyanobacterium make?
lichens
147
What is the relationship on lichens?
- alga is photosynthetic and make organic matter
- lichen acids dissolve rock releasing minerals
- fungus protects the microbe from dessication
148
What is Chlorochromatium aggregatum?
not a real name just a consortium between non-motile green sulfur and a motile non-phototrophic bacteria
149
What is the rhizosphere?
the region immediately outside the root
150
What is a phyllosphere?
surface of the plant leaf
151
Give an example of a legume
- soybean
- clover
- alfalfa
- beans
- peas
152
What is the role of nod factors?
Induce root hair curling
153
What are symbiosomes?
When rhizobia cells multiply in the plant it becomes swollen and mishaped and is called bacteroids. then the plant surrounds the bacteroids
154
What is leghemoglobin ?
a molecule capable of binding to oxygen
155
What is the bacterial genome?
all chromosomes and plasmids
156
Do plasmids carry essential genes?
No
157
When can plasmids replicate?
Any time during the cell cycle
158
What are the three periods in cell replication?
1. B period - birth
2. C period - replication (constant based on species)
3. D period - division
159
Which from of DNA is prominent and why?
Circular because;
- smaller
- less complication DNA replication
- resistance to exonnucleases
160
In which direction is DNA replicated?
5' -> 3'
161
What is the size of E coli genome?
4.6 x 10^6 bp
162
What is an advantage to having a divided genome?
Less time to replicate
163
What are two consequences for bacteria being haploid?
- mutation will have immediate consequence
| - allows genes to be turned on/off
164
How does HU binding protein work?
The Heat Unstable protein had an N-terminal and a C-terminal. C-terminal is a flexible arm for binding DNA
165
What enzyme supercoils DNA?
gyrase
166
What are operons?
Genes that are grouped together as they have related functions
167
Why is replication and translation done in the same direction?
If they were done in opposite directions it would result in head on collision and slow both processes
168
On average, how many base pairs per gene?
1 kb
169
What mediates protein splicing?
Self catalyzed by intein
170
Do all domains have inteins?
Yes
171
How does a cell turn on the promoter of Tn10?
must remove methylation
172
What are three ways to decrease the frequency of transposition?
1. only have a few promoters
2. have inactive promoters
3. only allow for a small window of time for this to occur
173
There are 6 requirements for the transposition process
1. DNA homology between TE and target site not required
2. Tnp encoded by TE mediates the transposition process (RecA independent)
3. Tnp recognizes a short target sequence
4. After transposition target sequence is duplicated forming a direct repeat
5. Tnp recognizes the inverted repeat at the end of the TE
6. insertion sites may or may not be random
174
Which TE are non-random?
Tn7 (ABCD) and Tn10
175
Which TE are random?
Mu, Tn5 and Tn7 (ABCE)
176
What does TnpA/B do?
recognize IR
177
What does TnpC do?
Connector or activator of tnp
178
What do TnpD/E do?
target site selection
179
What are the 2 classes of transposable elements?
1. Insertion sequences (IS)
| 2. Transposons
180
What must be present for an insertion sequence to move?
- must have transposase encoded
| - must be flanked by inverted repeats
181
What are the 2 types of transposons?
1. composite
| 2. complex
182
Give an example of a composite transposon
Tn5 (kan str bleo)
183
What is unique about composite transposon?
they transfer genes between two IS
184
What is an autonomous transposon?
Capable of moving on their own as they have tnp encoded
185
What is unique about complex transposons?
- not based on IS
| - transfer additional information
186
Give an example of a complex transposon
Tn3, Tn7
187
What is conservative transpositions?
the TE moves from one site to another and results in only 1 copy
ex. Tn5, Tn7
188
What is replicative transposition?
the TE copies in one site and inserts into another resulting in 2 copies
ex. Mu, Tn3
189
What must be present to have replicative transposition?
Resolvase
190
What are the consequences to TE?
1. Gene inactivation (insertional mutagenesis)
2. Turn on repressed genes
3. deletion via recombination
4. inversion via recombination
5. polar effect
6. gene translocation
191
What is the polar effect?
disruption of the first gene in an operon results in inactivation of downstream genes. The TE carries a transcription factor causing mRNA to prematurely terminate
192
How do plasmids replicate?
self replication
193
what are the different types of plasmids?
F -fertility
R
M - metabolism
Col - colicin (kills neighbor cell)
194
What are the most common forms of plasmids?
circular, double stranded
195
What genes are important in plasmids?
- ori : replication origin
- Rep : replication protein
- ABr : antibiotic resistance
196
What does Rep do in Theta mode?
recognizes ori and unwinds
197
What does Rep do in rolling circle mode?
recognizes ori and nicks
198
Give an example of a narrow host range
pBR322 only replicates in E coli
199
Give an example of broad host range
RK2 - gram negative
RSF101 - both gram - and +
200
The F plasmid has two specific genes, what are they?
CcdB (Controlled Cell Death)
| CcdA (antidote to CcB)
201
What are the 3 methods to horizontal transfer?
1. conjugation
2. transformation
3. transduction
202
What are two types of plasmids for conjugation?
1. self-transmissible
| 2. Mobilizable
203
Self transmissible requires two genes, what are they?
1. dtr (DNA Transfer and Replication)
| 2. mpf (mating Pair Formation)
204
Mobilizable only requires 1 gene. What is it?
mpf - mating pair formation
205
What does Hfr stand for?
High Frequency Recombination
| ex IS3
206
What is a suicide vector?
Can only replicate in E coli and so after conjugation the plasmid will not replicate in the host.
207
What is good about transformation?
it is fast acquisition of new genes
208
What are the 2 types of transformation?
1. natural
| 2. Artificial
209
Which bacteria are non-specific?
Streptococcus pneumoniae
bacillus subtilis
Helicobacter pyroli
210
Which bacteria are specific?
```
Haemophilus influenzae (5' AAGTGCGGT 3')
Neisseria gonorrhoeae (GCCGTCTCAA)
```
211
What are the two ways to make cells competent?
1. chemical
2. electrical
ex B subtilis become competent when the nutrients run out or high cell density during the early stationary phase
212
What are the 4 steps of DNA transformation in B subtilis and Streptococcus?
1. DNA binding (50 B, 10 S)
- reversible
2. Fragmentation
3. DNA uptake (ATP dependent)
- ds, no seq specificity
- as it enters cell the 5' end is degraded Strop
4. Recombination
213
What are the steps in transformation in Haemophilus?
1. competence developed in early stationary phase
2. makes transformase
3. must have AAGTGCGGT sequences
4. DNA uptake and recombination
214
What is the chemical method?
Use calcium to put pores in membrane during the mid log phase
215
How must the DNA be to be taken in?
Circular ds or ss. Linear gets degraded
216
Which is more effective chemical or electroporation?
electroporation (90%) vs chemical (10%)
217
What is special about Agrobacterium tumefaciens?
It is a pathogen to plants - induces tumor Crown gall
218
How does the bacteria attach to the plant cell?
- plant has pectin
| - bacteria has acidic acetylated capsular polysaccharide and cellulose fibril
219
What specifically induces the tumor?
Ti plasmid
220
Ti plasmid has 2 genes, what are they?
Oncogenes
- growth hormone
- hormone sensitizer
opines
221
What are the three basic forms of viruses?
1. Helical
2. Polyhedral
3. Complex
222
In what 2 states do viruses live in?
1. Intracellular state in infected host
| 2. Extracellular state in virion form
223
What is a capsomere?
Assemblage of subunits of the virus capsid
224
What viruses use the helical form?
- M13 phage
- rabies
- plant TMV
225
What virus uses complex form?
T4
226
What are the 2 steps in viral multipication?
1. Attachment
| 2. Penetration
227
What is a T4 long tail fiber made of?
LPS
228
What is a T4 tail pin (STF) made of?
LPS/OmpC
229
What is MS2 and M13 for?
conjugation pili
230
How do phage and virus differ in the penetration stage?
phage use DNA injection
| Virus use entry and uncoating (ex influenze o6)
231
What are the 4 regions of the T4 needle?
- gp27
- gp5 connector domain (N)
- gp5 lysozyme domain
- gp5 helical domain (C)
232
What are the 6 steps to phage invasion?
1. long tail fiber attach (reversible)
2. short tail fiber attach (irreversible)
3. DNA releases into tail tube
4. Sheath contraction -> rotation of tail tube -> screw and punch actions
5. tail tube penetrates outer membrane and lysozyme digests small opening in peptidoglygan
6. DNA ejection
233
What are two methods that T4 use for DNA ejection?
1. internal pressure
| 2. Proton gradient
234
What are two different types of tail?
Contractile Ex. T2, T4, Mu
Non-contractile
Long Ex. Lambda, T1, T5
Short Ex. T7
235
Why does T4 DNA have direct repeat at each end?
Allows the DNA to become circular after being placed into the host
236
What does burst size mean?
How many phage are released for every infected cell
| T4 is 200
237
What does DNase do?
Consists of DenA and DenB that cut only cytosine containing DNA
238
What does T4 Unf do?
- unfolds the nucleoid (C containing DNA)
| - blocks transcription of host DNA
239
How do the phage obtain nucleotides?
- host DNA
| - New dNTP biosynthesis
240
What are concatamers?
Concatamers are formed when the DNA is replicated and the overhang of one strand bonds with another so as not to lose any DNA
241
What are the 3 units associated with DNA packaging?
gp20
gp17 N and C domain
gp16
242
What does gp 20 do?
acts as a channel into the phage head
243
What does gp17 do?
The N domain ATPase acts as a pump (2bp/ATP) the C domain binds to the DNA and Cleaves it once the head is full
244
What does gp16 do?
speeds up ATPase
245
What does H1N1 stand for?
```
h= hemagglutinin
n= neuraminidase
```
246
How does Tamiflu work?
Inhibits neuraminidase
247
What shape are proteins in for secretion in sec-dependent manor?
Unfolded so they will fit through the pores
248
Describe the Twin Arginine Translocation (TAT) requirements
- must have S/TRRXFLK
| - sec independent
249
What are two types of proteins that are gram negative specific?
- periplasmic proteins
| - outer membrane proteins
250
What are the four components of sec-dependent protein secretion?
1. N-terminal signal sequence
2. membrane channel
3. translocase SecA
4. chaperone proteins (prevent folding)
251
What is the energy source for Sec-dependent protein secretion?
- ATP
| - proton gradient
252
Where will peptidase cleave the signal seqence?
after ala-x-ala followed by neutral or negative aa
253
What are the two functions of SecB chaperone?
1. keeps protein unfolded
| 2. targets preproteins to translocase (SecA) on the membrane
254
Does SecA require ATP?
Yes, ATP allows SecA to bind with SecY/E/G
255
What is the microbiome on humans?
all microorganisms on or in the human body
256
What are considered normal microbial flora?
microbes usually found associated with a particular human body
257
What is the core microbiome?
microorganisms that are found on the same site on most people throughout life
258
How do the microbiota of the GI tract affect humans?
- early development
- health
- predisposition to disease
259
What are the 4 main phylotypes found in humans?
Firmucutes
Bacteroidetes
Proteobacteria
Actinobacteria
260
What bacteria group colonise sweat glands and skin?
gram positive
261
What bacteria forms dental plaque?
Streptococci
262
What area of the respiratory system is colonized?
Upper not lower
263
Does the urogenital tract have bacteria?
No, if E coli or P mirabilis are present they cause UTI
264
Define septicemia
a bloodborn systemic infection
265
define toxicity
the ability of an organism to cause disease by means of a preformed toxin that inhibits host cell function or kills host cell
266
define Virulence
the relative ability of a pathogen to cause disease
267
What is a pathogen?
a disease causing microorganism
268
define opportunistic pathogen
an organism that causes disease in the absence of normal host resistance
269
What are virulence factors?
Enzymes produced by the pathogen to
- break down or alter host tissue to provide access to nutrients Ex. hyaluronidase
- protect pathogen by interfering with host defense
Ex. coagulase
270
What are exotoxins?
proteins released from the pathogen cell as it grows
271
What are three categories of exotoxins?
- cytolytic -> lyse membrane
- AB toxins -> intercellular poison
- superantigen toxins -> take over immune system
272
How does Diptheria exotoxin work? (AB)
prevents protein synthesis
273
How does botulism work?
Prevents the release of acetylcholine that would stimulate muscle contraction
274
How does tetanus toxin work?
Prevents the release of glycine in inhibitory interneurons causing muscles to stay contracted
275
What are endotoxins?
Toxins that are released upon lysis of bacteria
276
What are three features of the adaptive immune response?
1. specificity
2. Memory
3. tolerance
277
How are antigens recognized?
- linear
- conformational
- can be just 4-6 aa long
278
How do T cells recognize an antigen?
antigen must be bound to MHC (major histocompatibility complex)
279
Where do we find MHC I?
on all nucleated cells, this is how our body recognizes our tissues
280
Where do we find MHC II?
only on anitgen presenting cells like
- macrophages
- b cells
- dendritic cells
281
How doe MHC I and MHC II differ?
MHC II is not limited to the number of amino acids it can bind whereas MHC I can only bind 8 -11 amino acids
282
What do granzymes do?
they are a protease that stimulates apoptosis
283
What is positive selection of T cell education?
t cells interact with self MHC then proliferate. Takes place in the thymus
284
What is negative selesction of t cell education?
t cells are eliminated if they strongly interact with self MHC this takes place in the medullar region
285
What are the three languages of quorum sensing?
- Autoinducer 1
- short peptides
- autoinducer 2
286
What are the key components of quorum sensing?
1. signal generation
2. signal detection
3. response -> gene activation
287
Where do we find autoinducers?
gram negative
288
What is LuxI/LuxR used for?
Lux1 makes AI-1 while LuxR senses AI-1
289
How does autoinducer work?
receives a chemical signal like serine, homoserne, homoserine lactone, acyl-homoserine lactone
