Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MicroEco > Lecture 15 - Microbial Communication > Flashcards

Lecture 15 - Microbial Communication Flashcards

1
Q

What must bacteria be able to do in order to survive due to the fact that the environments they inhabit are complex and subject to rapid change?

A

must adapt by being able to sense and respond to the rapid changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 6 functions of bacterial communication?

A

coordination of gene expression within a single or unrelated population(s) | evade host immune response | coordinate virulence gene expression | inhibit a competitor | inhibit/stimulate host colonization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 3 different kinds of bacterial communication?

A

intraspecies, interspecies, and inter-kingdom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is intraspecies signaling?

A

communication within a population of same species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is interspecies signaling?

A

communication between populations of different species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is inter-kingdom signaling?

A

abusing signal pathways by signaling molecules of one organism (bacteria) to change behavior of another organism (animal) from a different kingdom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are bacterial pheromones?

A

signals that alter bacterial behavior

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the characteristics of communication signals that bacteria use to communicate?

A

small molecules released from cell (active transport or passive diffusion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What must cells – that a bacteria is attempting to communicate with – must possess?

A

the ability to recognize the signaling molecules = receptors = can be within cells or on surface of cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is quorum sensing?

A

type of bacterial communication that regulates gene expression due to signaling molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is quorum sensing dependent on?

A

population dependent <> population density increases = quantity of signaling molecules increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which type of bacteria uses quorum sensing?

A

both gram+ and gram– but use different signal molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 4 ecological roles of quorum sensing?

A

coordinate gene expression (within one species or between different species), evade host immune responses, direct signaling between bacterium and host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is AHL?

A

N-acyl homoserine lactone = best studied diffusible signal, many bacterial species can produce this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the structural components of AHL? Which part stays consistent?

A

homoserine lactone ring and fatty-acyl side chain | the homoserine lactone ring stays consistent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which bacterium uses AHL? Which one can’t and why?

A

gram– | gram+ can’t use AHL because they lack a porous outer membrane (like seen in gram– cells) instead they have a thick peptidoglycan cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is specificity determined by within the AHL molecule?

A

length and modifications of side chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is vibrio fischeri? Where are they found on?

A

marine bacteria capable of bioluminescence found free-living within the ocean OR attached on the light organ of an animal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the population density of Vibrio fischeri when it is in the open ocean? What is the consequence of this in terms of cell signaling? What operon transcription depends on this signaling pathway?

A

low density = low chemical signaling activity | the Lux operon = won’t be transcribed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the population density of Vibrio fischeri when it is on the light organ of a marine animal? What is the consequence of this in terms of cell signaling?

A

high population density because they are more concentrated within one area = high chemical signaling activity &raquo_space;> signals diffuse into cells and bind to transcription factor for Lux-operon = luminescence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the Lux operon expression dependent on?

A

amount of AHL molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What do the signal molecules function closely as?

A

transcription factors that can inhibit or enhance gene expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where are the genes, that these signaling molecules control, usually located at?

A

on an operon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is another name for interspecies signaling?

A

“cross-talk”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What was the example discussed in class to explain how interspecies signaling works?
Pseudomonas species produce phenazines
26
What are phenazines?
three-pigmented antibiotics
27
What is positive cross-talk?
species A restores the ability of an activity in species B | beneficial type of communication
28
What is negative cross-talk?
species A inhibits the ability of an activity in species B | detrimental type of communication
29
What causes Crown galls disease in plants?
A. tumefaciens
30
What are the symptoms of Crown galls disease?
development of "galls" at the soil surface or "crown" of the plant
31
What are galls?
tumor-like structures as a result of a lot of cell-division triggered by A. tumefaciens
32
Where are the genes necessary for the bacteria to cause Crown galls disease found at?
on a plasmid in which region will be transferred to the plant genome
33
How does A. tumefaciens engineer the plant?
inserts genes from plasmid into plant genome in order for it to produce food source that bacterium needs
34
What is the sensor protein? What does it act as? Where is it located?
senses environmental signal | acts as a kinase = phosphorylates response regulator | found on plasma membrane
35
What is the response-regulator? What does it act as? Where is it located?
acts on whatever the cell needs to do to respond appropriately according to the signal received | acts as a transcription factor (activator/repressor) | found in cytoplasm
36
What initiates the bacterial infection of A. tumefaciens to the plant to cause Crown galls disease?
plant gets damaged and releases many compounds
37
When the plant is damaged, what are the compounds it releases? What do these compounds act as? How does A. tumefaciens interact with these compounds?
phenolic compounds act as signaling molecules >>> interacts with sensor protein on A. tumefaciens
38
What are the sequence of events following the sensor protein on A. tumefaciens interacting with phenolics?
sensor kinase = phosphorylates response-regulator(RR) >>> RR induce gene expression from plasmid >>> gene transcription product = excised as T-DNA >>> T-DNA transferred into wounded cell and localizes to nucleus >>> T-DNA inserts into plant chromosome
39
What is T-DNA?
the region of the plasmid that is transferred into the plant in response to plant signals following wounding
40
What is the food source of A. tumefaciens that plants are engineered to produce?
opines
41
What are opines?
nitrogen and carbon-containing compounds
42
What does transcription of T-DNA lead to? (2things)
opines and plant hormones
43
What is the function of opines? (A. tumefaciens)
binds to the repressor = cause conformational change = repressor falls off = transcription of genes
44
What happens if there are no opines available?
the repressor is bound to genes that activate conjugation
45
What is conjugation?
a way to share DNA/transfer plasmids between cells
46
What effect does the T-DNA have on the plant that causes Crown gall's disease?
produces plant growth hormones = plant will grow & constant cell division = galls
47
How does A. tumefaciens maintain the plasmid within the population?
quorum sensing mechanism is needed to activate the conjugation genes so it can go and share its plasmid to other bacteria
48
What is the signaling molecule needed for quorum sensing mechanism with A. tumefaciens?
opines
49
How can we use quorum sensing as a type of biocontrol?
develop engineered microbes that can easily bread down quorum sensing signals such as opines and AHLs
50
What signaling molecule do gram+ bacteria use?
small peptides which are different in structure compared to AHLs
51
What does S. aureus use as a signaling molecule?
auto-inducing peptide (AIP)
52
What is S. aureus?
human pathogen uses quorum sensing as part of its pathogenesis
53
What is a "pro-peptide"?
peptide + some sequence that will be processed with a protease to create AIP
54
What is the function of AIP? (3 functions)
upregulates transcription of: pro-peptide = AIP and RNA III and downregulates transcription of cell surface proteins
55
Why would S. aureus want to downregulate expression of cell surface proteins?
less cell surface proteins = hide from host immune system
56
What is significant about RNA III?
results in the production of virulence factors
57
What type of system does S. aureus use?
The three-component system
58
What is the "three-component system"?
the 2-component system + quorum sensing
59
What is lactobacillus?
found in our gut and is one of our probiotics
60
In what ways can lactobacillus help protect us against pathogens like S. aureus?
colonizing our gut can help prevent colonization of S. aureus | its inducing peptides (IPs) bind to surface protein on membrane >>> 2-component regulatory system produces: bacteriocin and pre-IP
61
What is bacteriocin?
targets pathogens
62
What is the function of the small non-coding mRNA used in the quorum sensing system?
binds to Lux-operon mRNA = leads to degradation of Lux-operon mRNA = no bioluminescence
63
When would the small non-coding mRNA, used in the quorum sensing system, not be produced?
when there is a high concentration of signaling molecules = last Lux-operon mRNA will not be phosphorylated = bioluminescence
64
What is a neuropeptide?
fragment of peptidoglycan
65
What is a neuropeptide indicative of?
bacterial cell was lysed or cell-wall-degrading antibiotic is present
66
What do spore-forming bacteria use neuropeptides as?
as germinants to trigger vegetative growth
67
What can eukaryotes use neuropeptides as?
as a signal that a bacterium is present within host tissues
68
What is quorum quenching?
the idea of preventing quorum sensing mechanisms
69
What are the 3 ways that quorum quenching can block the quorum sensing mechanisms?
prevents synthesis of signaling molecules (small peptides and AHLs) | interfere with signal receptor | directly inactivate signaling molecules
70
What is the sequence of events when lactobacillus binds to S. aureus' AIP? (relating to quorum quenching)
recognition of AIP triggers lactobacillus to produce and release RNA-III-inhibiting protein (RIP) >>> S. aureus uptakes RIP = causes degradation of RNA III within S. aureus = prevents toxin production
71
What are the 3 consequences of interkingdom signaling?
bacteria can eavesdrop on host by responding to host signals | host-interfering signals can interfere with bacterial signaling | host can undergo altered host gene expression when it recognizes bacterial signals
72
What are the 2 quorum sensing systems that Pseudomonas uses?
uses virulence factors and some AHLs
73
In what ways do the AHLs produced by pseudomonas influence host defensive responses? (the Pseudomonas that colonize the lung tissues of ICPs (immunocompromised patients/people))
downregulates lymphocyte proliferation; downregulates production of immune cells, and reduces apoptosis (when cell knows its infected)
74
What is a regulon?
a higher order operon-type structure where a lot of genes/operons are regulated and triggered by 1 signaling molecule
75
What can easily overwhelm the immune system?
quorum sensing mechanisms and regulon

MicroEco (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions