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Micro 402 > quiz 5 > Flashcards

quiz 5 Flashcards

1
Q

What is the significance of Quorum sensing?

A

QS allows an entire population to behave as a unified group

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2
Q

What must happen for a quorum to be reached?

A

Signaling molecules must accumulate and reach a threshold before quorum sensing can occur, usually requires a dense population of cells.

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3
Q

How do lux genes work in vibrio fischeri?

A

LuxI synthesizes AHL that luxR can can detect AHL and activate the lux genes.

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4
Q

What cellular functions is quorum sensing related to?

A

exoenzyme synthesis, conjugation, antibiotic production, swarming motility, biofilm formation

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5
Q

What does it mean for a bacteria to be multilingual?

A

Many AHL signals are very similar, a multilingual bacteria is one that can recognize multiple AHL signals.

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6
Q

Why do we use an indicator strain in QS experiment?

A

The indicator can accept multiple signals but not transmit them, if it accepts a signal then it will turn purple due to violaceum synthesis .

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7
Q

Does a negative result mean that no quorum sensing is possible?

A

No, it means that the indicator may not be able to recognize the signal.

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8
Q

BT: What is transformation?

A

The uptake of DNA from environment

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9
Q

BT: What is conjugation?

A

transfer from one donor to recipient via cell to cell contact

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10
Q

BT: what is transduction?

A

bacterial DNA is mistakenly packaged into phage capsids and transferred to new cells

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11
Q

what is genetic competence?

A

when cells take up and incorporate DNA from the environment

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12
Q

What is induced competence?

A

only take up DNA when treated with CaCl2, like e.coli

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13
Q

What is a genetic marker?

A

A new trait that is acquired that is not present in other cell genomes

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14
Q

What is an auxotroph?

A

a nutritionally deficient mutant strain

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15
Q

What is a prototroph?

A

A nutritionally competent WT cell with biosynthetic capabilities

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16
Q

What is the purpose of DNase in the BT experiment?

A

if transformation is possible, DNase will degrade free DNA so transformation is terminated.

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17
Q

What is a bacteriophage?

A

A virus that infects bacteria

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18
Q

What does a phage look for/need in a host?

A

active host with healthy replication medium

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19
Q

Why did we inoculate our plaque with E.Coli?

A

Our plaque needs bacteria to feed off of.

20
Q

What is a capsid?

A

protein coat that covers virus

21
Q

Why are viruses not considered living entities?

A

They cannot replicate on their own

22
Q

What is a plaque?

A

A visible zone of clearing that occurs when phages have replicated multiple times on a lawn

23
Q

What is a co-culture?

A

A bacteriophage grown with bacterial host?

24
Q

What is a lysate?

A

a pure suspension of bacteriophages that have been removed from co-cultures.

25
Q

What is the purpose of soft-agar?

A

allows bacteriophage to diffuse more easily and uniformly during plaque formation

26
Q

What is a titer?

A

The concentration of bacterial cells present within a lysate.

27
Q

What is a rhizosphere?

A

the upper layer of fertile soil

28
Q

What is the morphology of of actinomycetes? Why is it unique?

A

They are obligate aerobes that have individual cells that elongate without dividing to form long branching filaments containing multiple copies of the genome

29
Q

What kind of metabolism do actinomycetes do?

A

chemoheterotrophs that can degrade recalcitrant polymers

30
Q

What is a hyphae?

A

Individual filaments of actinomycetes that grow into a mycelium

31
Q

What happens when the center of an actinomycete colony becomes nutrient starved?

A

hyphae grow vertically away from substrate to form aerial hyphae. Individual cells of aerial hyphae is conidia. Hyphal structure with conidia is sporophore

32
Q

What organic compound do actinomycetes produce?

A

polycyclic carbs called geosmins, which give off earthy smell of soil

33
Q

What makes chapels agar more selective?

A

contains sodium nitrate as nitrogen source and sucrose as carbon source, make media selective bc nitrate is difficult to assimilate and sucrose inhibits swarming behavior of bacillus

34
Q

How does gel electrophoresis work?

A

separates fragments by size, Negatively charged DNA migrates through the gel towards positive electrode. Smaller fragments move quicker. Smallest one is farthest away from well

35
Q

What is taxonomy?

A

science of classifying living organisms

36
Q

What is phylogeny?

A

evolutionary history of an organism

37
Q

What are the main differences between azomonas and azotobacter?

A

azotobacter is butanol positive(forms cysts), isolated from soil and urease positive

38
Q

What will the results of the motility deep look like?

A

nonmotile cells will be a dark red line along the length of the stab, pink color spreading away from the stab is motile.

39
Q

What does it mean to be naturally competent?

A

they have the ability to tale up and incorporate free DNA directly from the environment.

40
Q

What does it mean for something to be nutritionally fastidious?

A

they have a variety of nutritional requirements that must be met by their plants or animal hosts, making them hard to cultivate in lab

41
Q

Whats the main difference between agarose and agropectin?

A

agarose is neutral charged and agaropectin is negatively charged.

42
Q

What is the purpose of using SWC media with agar-degrading bacteria?

A

TO see if they do catabolite repression, using nutrients in a rich media instead of agar(looking for a decrease in agarase)

43
Q

What does nutritionally fastidious mean?

A

Picky, require many things to grow successfully

44
Q

What are lactic acid bacteria morphology?

A

gram positive cocci

45
Q

What do we expect to see on the TSY plate?

A

It is trp +, we expect to see no growth. Growth on this plate due to unlysed donor cells in the solution

46
Q

What are we looking for In our purple non sulfur wet mounts?

A

motile, helical shaped cells-rhodospirillum
long, irregular rods with swollen tip-rhodopseudomonas

Micro 402 (15 decks)

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