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Micro 402 > quiz 4 > Flashcards

quiz 4 Flashcards

1
Q

What is Nitrogen fixation?

A

reduction of N2 gas to ammonia

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2
Q

what enzyme complex catalyzes N2 reduction?

A

nitrogenase

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3
Q

Why di we need to perform azotobacteria under completely anaerobic conditions?

A

Because nitrogenase is extremely sensitive to molecular oxygen and reacting with O2 will make is irreversibly inactivated

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4
Q

What is the azotobacteria morphology?

A

large, gram negative, gram variable rods

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5
Q

What happens when azotobacteria are grown on a non-nitrogen surface? Why?

A

produce EPS slime as diffusion barrier to consume oxygen as it enters

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6
Q

How are azotobacter and azomonas primarily distinguished?

A

Azotobacter can form metabolically inert cysts(butanol positive).

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7
Q

What conditions can azotobacter cysts stand, and not stand?

A

Cysts are resistant to nutrient starvation and desiccation, but not to heat and other physical or chemical assaults.

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8
Q

What are they key features of azotobacter?

A

found in soil, positive for urease (can use urea as a nitrogen source)

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9
Q

what are the key features of azomonas?

A

found in freshwater, urease negative

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10
Q

What is the purpose of a butanol slant in azotobacteria?

A

Induces cyst formation in azotobacter

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11
Q

What do the results of the urease slant tell us?

A

Positive result means they can use urease as a nitrogen source the agar will be pink.

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12
Q

How do purple and green sulfur bacteria differ from non sulfur bacteria?

A

They are obligate aerobes that use H2S as an electron donor for biosynthesis

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13
Q

How do green gliding and purple non sulfur bacteria differ?

A

Grow in the presence of oxygen and are inhibited by high levels of sulfide

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14
Q

What is the morphology of purple non sulfur bacteria?

A

gram negative with cell shapes ranging from short cocobacilli to straight and helical rods

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15
Q

Why did we use Kings B agar for pseudomonads?

A

It is a nutrient limited medium that induces difficult pigment production.

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16
Q

Why did we use nutrient broth for Pseudomonads?

A

Test ability to grow at high temp

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17
Q

Why did we use a gelatin deep for pseudomonads?

A

Test isolates ability to hydrolyze gelatin using gelatinase

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18
Q

What are the control plates in the pseudomonads experiment? What is the purpose of the other plates?

A

Acetate and asparagine are the positive control plates, the plate with nothing is the negative growth plate, the rest of the plates are to test different carbon and energy sources.

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19
Q

What is ecological succession?

A

changes in the species present within a community over time

20
Q

How is the final product preserved?

A

high salt and high acidity inhibits the growth of potential spoilage

21
Q

Why is it unusual that lactic acid bacteria are catalase negative?

A

They are grown in the presence of oxygen, nut use peroxidase to to eliminate toxic hydrogen peroxide.

22
Q

What is an aerotolerant anaerobe?

A

anaerobes metabolically grown in the presence of oxygen

23
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

24
Q

what is homolactic acid fermentation?

A

oxidize glucose to two molecules of pyretic acid, then reduce each to lactic acid. Net: 2 ATP, 2 Lactic Acid

25
Q

What is heterolactic acid fermentation?

A

decarboxylate glucose to one molecule of acetate and one molecule of pyruvate, then form ethanol and lactic acid. Net: 1 ATP, 1 Lactic acid, 1 ethanol, 1 CO2

26
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.

27
Q

How will we enrich for acinetobacter, how will we give them an advantage?

A

Grow them on an unusual carbon source (acetate), to give advantage, we will use a slightly acidic medium that contains potassium nitrate as sole nitrogen source.

28
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.

29
Q

Where are agar degrading bacteria found?

A

seawater and freshwater sediment

30
Q

What kind of metabolism to propionic bacteria do?

A

grow only by fermentation, aeroduric

31
Q

What are diphtheroids?

A

Diphtheroids are gram positive cells with irregular, swollen rod shaped cells

32
Q

Where are propionic bacteria commonly found?

A

Swiss cheese and under the surface of our skin

33
Q

Why did we clean our skin with alcohol?

A

TO remove the S.Epidermidis on the skin surface

34
Q

PARE:What antibiotics target protein synthesis?

A

tetracycline, chlormaphenicol, kanamycin

35
Q

PARE: what abtiribotics target cell wall and outer membrane?

A

membrane: triclosan
outer membrane: polymyxin
cell wall: vancomycin, ampicillin

36
Q

PARE: what does nalidixic acid acid target?

A

DNA replication

37
Q

What is taxonomy?

A

science of classifying living organisms

38
Q

What is phylogeny?

A

evolutionary history of an organism

39
Q

Why is the rRNA universally adopted?

A

small subunit of rRNA gene occurs in all living organisms, large enough to contain statistically meaningful amount of information, performs same function in all organisms. contains highly conserved regions that allow comparisons of very divergent organisms, as well as highly variable regions, reflects vertical transfer

40
Q

Why can sourdough starter go for so long?

A

ecological succession, waste products choke out other products

41
Q

What is oxygenic phototrophy?

A

Uses light energy in PS2 to convert H2O to O2

42
Q

What is anoxygenic phototrophy?

A

no PS2, PS1, H2S to sulfate

43
Q

What is the role of tetracycline in the ZOI pare project?

A

Positive control, we know we’ll get a positive result

44
Q

Why do we sequence 16s ribosomal RNA?

A

it is broadly conserved and universal

45
Q

What are the main differences between azomonas and azotobacter?

A

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

46
Q

What does it mean for something to be biphasic?

A

Partially antibiotic resistant

47
Q

What do we observe w kings B agar (in relation to siderophores?

A

Bacteria may secrete siderophores (like pyocyanin) to scavenge iron for virulence factor growth, kings B agar inhibits this so that green fluorescent protein is not expressed.

Micro 402 (15 decks)

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