quiz 4

Question 1

What is Nitrogen fixation?

Answer 1

reduction of N2 gas to ammonia

Question 2

what enzyme complex catalyzes N2 reduction?

Answer 2

nitrogenase

Question 3

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

Answer 3

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

Question 4

What is the azotobacteria morphology?

Answer 4

large, gram negative, gram variable rods

Question 5

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

Answer 5

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

Question 6

How are azotobacter and azomonas primarily distinguished?

Answer 6

Azotobacter can form metabolically inert cysts(butanol positive).

Question 7

What conditions can azotobacter cysts stand, and not stand?

Answer 7

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

Question 8

What are they key features of azotobacter?

Answer 8

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

Question 9

what are the key features of azomonas?

Answer 9

found in freshwater, urease negative

Question 10

What is the purpose of a butanol slant in azotobacteria?

Answer 10

Induces cyst formation in azotobacter

Question 11

What do the results of the urease slant tell us?

Answer 11

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

Question 12

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

Answer 12

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

Question 13

How do green gliding and purple non sulfur bacteria differ?

Answer 13

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

Question 14

What is the morphology of purple non sulfur bacteria?

Answer 14

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

Question 15

Why did we use Kings B agar for pseudomonads?

Answer 15

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

Question 16

Why did we use nutrient broth for Pseudomonads?

Answer 16

Test ability to grow at high temp

Question 17

Why did we use a gelatin deep for pseudomonads?

Answer 17

Test isolates ability to hydrolyze gelatin using gelatinase

Question 18

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

Answer 18

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.

Question 19

What is ecological succession?

Answer 19

changes in the species present within a community over time

Question 20

How is the final product preserved?

Answer 20

high salt and high acidity inhibits the growth of potential spoilage

Question 21

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

Answer 21

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

Question 22

What is an aerotolerant anaerobe?

Answer 22

anaerobes metabolically grown in the presence of oxygen

Question 23

What does it mean for something to be nutritionally fastidious?

Answer 23

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 24

what is homolactic acid fermentation?

Answer 24

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

Question 25

What is heterolactic acid fermentation?

Answer 25

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

Question 26

What does it mean to be naturally competent?

Answer 26

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

Question 27

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

Answer 27

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.

Question 28

What will the results of the motility deep look like?

Answer 28

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

Question 29

Where are agar degrading bacteria found?

Answer 29

seawater and freshwater sediment

Question 30

What kind of metabolism to propionic bacteria do?

Answer 30

grow only by fermentation, aeroduric

Question 31

What are diphtheroids?

Answer 31

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

Question 32

Where are propionic bacteria commonly found?

Answer 32

Swiss cheese and under the surface of our skin

Question 33

Why did we clean our skin with alcohol?

Answer 33

TO remove the S.Epidermidis on the skin surface

Question 34

PARE:What antibiotics target protein synthesis?

Answer 34

tetracycline, chlormaphenicol, kanamycin

Question 35

PARE: what abtiribotics target cell wall and outer membrane?

Answer 35

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

Question 36

PARE: what does nalidixic acid acid target?

Answer 36

DNA replication

Question 37

What is taxonomy?

Answer 37

science of classifying living organisms

Question 38

What is phylogeny?

Answer 38

evolutionary history of an organism

Question 39

Why is the rRNA universally adopted?

Answer 39

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

Question 40

Why can sourdough starter go for so long?

Answer 40

ecological succession, waste products choke out other products

Question 41

What is oxygenic phototrophy?

Answer 41

Uses light energy in PS2 to convert H2O to O2

Question 42

What is anoxygenic phototrophy?

Answer 42

no PS2, PS1, H2S to sulfate

Question 43

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

Answer 43

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

Question 44

Why do we sequence 16s ribosomal RNA?

Answer 44

it is broadly conserved and universal

Question 45

What are the main differences between azomonas and azotobacter?

Answer 45

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

Question 46

What does it mean for something to be biphasic?

Answer 46

Partially antibiotic resistant

Question 47

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

Answer 47

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.