quiz 5

Question 1

What is the significance of Quorum sensing?

Answer 1

QS allows an entire population to behave as a unified group

Question 2

What must happen for a quorum to be reached?

Answer 2

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

Question 3

How do lux genes work in vibrio fischeri?

Answer 3

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

Question 4

What cellular functions is quorum sensing related to?

Answer 4

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

Question 5

What does it mean for a bacteria to be multilingual?

Answer 5

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

Question 6

Why do we use an indicator strain in QS experiment?

Answer 6

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

Question 7

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

Answer 7

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

Question 8

BT: What is transformation?

Answer 8

The uptake of DNA from environment

Question 9

BT: What is conjugation?

Answer 9

transfer from one donor to recipient via cell to cell contact

Question 10

BT: what is transduction?

Answer 10

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

Question 11

what is genetic competence?

Answer 11

when cells take up and incorporate DNA from the environment

Question 12

What is induced competence?

Answer 12

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

Question 13

What is a genetic marker?

Answer 13

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

Question 14

What is an auxotroph?

Answer 14

a nutritionally deficient mutant strain

Question 15

What is a prototroph?

Answer 15

A nutritionally competent WT cell with biosynthetic capabilities

Question 16

What is the purpose of DNase in the BT experiment?

Answer 16

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

Question 17

What is a bacteriophage?

Answer 17

A virus that infects bacteria

Question 18

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

Answer 18

active host with healthy replication medium

Question 19

Why did we inoculate our plaque with E.Coli?

Answer 19

Our plaque needs bacteria to feed off of.

Question 20

What is a capsid?

Answer 20

protein coat that covers virus

Question 21

Why are viruses not considered living entities?

Answer 21

They cannot replicate on their own

Question 22

What is a plaque?

Answer 22

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

Question 23

What is a co-culture?

Answer 23

A bacteriophage grown with bacterial host?

Question 24

What is a lysate?

Answer 24

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

Question 25

What is the purpose of soft-agar?

Answer 25

allows bacteriophage to diffuse more easily and uniformly during plaque formation

Question 26

What is a titer?

Answer 26

The concentration of bacterial cells present within a lysate.

Question 27

What is a rhizosphere?

Answer 27

the upper layer of fertile soil

Question 28

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

Answer 28

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

Question 29

What kind of metabolism do actinomycetes do?

Answer 29

chemoheterotrophs that can degrade recalcitrant polymers

Question 30

What is a hyphae?

Answer 30

Individual filaments of actinomycetes that grow into a mycelium

Question 31

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

Answer 31

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

Question 32

What organic compound do actinomycetes produce?

Answer 32

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

Question 33

What makes chapels agar more selective?

Answer 33

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

Question 34

How does gel electrophoresis work?

Answer 34

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

Question 35

What is taxonomy?

Answer 35

science of classifying living organisms

Question 36

What is phylogeny?

Answer 36

evolutionary history of an organism

Question 37

What are the main differences between azomonas and azotobacter?

Answer 37

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

Question 38

What will the results of the motility deep look like?

Answer 38

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

Question 39

What does it mean to be naturally competent?

Answer 39

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

Question 40

What does it mean for something to be nutritionally fastidious?

Answer 40

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

Question 41

Whats the main difference between agarose and agropectin?

Answer 41

agarose is neutral charged and agaropectin is negatively charged.

Question 42

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

Answer 42

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

Question 43

What does nutritionally fastidious mean?

Answer 43

Picky, require many things to grow successfully

Question 44

What are lactic acid bacteria morphology?

Answer 44

gram positive cocci

Question 45

What do we expect to see on the TSY plate?

Answer 45

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

Question 46

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

Answer 46

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