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BIOL 240 > Module 7A > Flashcards

Module 7A Flashcards

Bacterial MVPs

1
Q

how do purple bacteria gain energy

A

anoxygenic photosynthesis

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2
Q

what pigments enable anoxygenic photosynthesis in purple bacteria

A

bacteriochlorophylls & carotenoid pigments

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3
Q

where are pigments of purple bacteria stored

A

intracytoplasmic membranes

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4
Q

how is colour determined in purple bacteria

A

it’s dependent on their specific mix of bacteriochlorophylls (blue) & carotenoids (red)

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5
Q

what do purple bacteria use as their electron source

A

sulfide, typically hydrogen sulfide

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6
Q

where does elemental sulfur accumulate in purple sulfur bacteria

A

in the periplasm or externally

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7
Q

what happens to the sulfur in purple bacteria

A

it gets accumulated as waste or oxidized to sulfate

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8
Q

what is mixotrophic growth

A

the organism can grow with either organic carbon or carbon dioxide

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9
Q

what is the relationship between purple bacteria and oxygen

A

oxygen inhibits their photosynthesis, but some can grow with respiration

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10
Q

where is purple sulfur bacteria found

A

places with light, low/no oxygen, and lots of sulfur

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11
Q

what is the difference between purple sulfur bacteria and purple nonsulfur bacteria

A

purple nonsulfur bacteria also use hydrogen sulfide, but prefer lower concentrations

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12
Q

what are methylotrophs

A

bacteria that can oxidize one-carbon compounds

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13
Q

what are methanotrophs

A

methylotrophs that use methane

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14
Q

what enzyme to methanotrophs contain

A

methane monooxygenase (MMO)

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15
Q

what does MMO do

A
  • oxidizes methane to methanol
  • the methanol can be further oxidized to CO2 or used for assimilation into biomass
  • MMO can co-oxidize a diverse array of carbon sources
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16
Q

what can methylotrophs gain from methane

A

energy, electrons, and carbon

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17
Q

what is the relationship between methanotrophs and oxygen

A

they are obligate aerobes (use O2 as their terminal electron acceptor), some are microaerophilic

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18
Q

where are methanotrophs found

A

in a variety of environments that contain methane and oxygen

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19
Q

how do nitrifiers gain energy and electrons

A

most use NH3 and convert it to nitrate, some use and convert nitrite to nitrate

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20
Q

are nitrifiers autotrophic or heterotrophic

A

autotrophic

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21
Q

what is comammox and which bacteria are capable of it

A

it is complete ammonia oxidation, ammonia -> nitrite -> nitrate; capable in specific species of Nitrospira

22
Q

what enzyme is used for ammonia oxidation

A

ammonia monooxygenase enzyme (AMO)

23
Q

what enzyme is used for nitrate oxidation

A

nitrite oxidoreductase (Nxr)

24
Q

how are nitrifiers names

A
  • oxidize ammonia: Nitroso-
  • oxidize nitrite: Nitro-
25
where are nitrifiers found
in many different environments such as soils, sediments, and water columns; ammonia and nitrate oxidizers are often found growing in close association
26
where are the key enzymes AMO and Nxr often found in nitrifiers
in internal membrane systems
27
what is the metabolic category of Pseudomonads (and oxygen exposure)
aerobic chemoorganoheterotrophs
28
what flagella do Pseudomonads have
polar flagella
29
which group is very heterogeneous, being split up into Pseudomonas, Burkholderia, Ralstonia, and Comamonas
Pseudomonads
30
why are some Pseudomonads flourescent
they produce a siderophore called pyoverdin which is used to acquire iron from a cell's external environment
31
what is the problem of nitrogen-fixing bacteria in environments with oxygen
the enzyme nitrogenase used for nitrogen fixation is irreversibly inactivated by oxygen
32
how do nitrogen-fixing bacteria combat oxygen
they protect themselves from excessive free O2 with a thick capsule that allows just enough O2 for respiration; other bacteria are anaerobic and don't associate with these environments
33
what are some features of Rhizobia
- part of Alphaproteobacteria - aerobic Gram-negative rods - usually soil or plant associated
34
how do Agrobacterium cause crown gall disease
- the bacterium infects the crown of a plant - if forms a tumor - it sends a plasmid into the genome of the plant - it causes the plant to make unique amino acids called opines that only the bacteria can use
35
what relationship do Rhizobium form
symbiotic relationships with leguminous plants
36
how do Rhizobium form root nodules
- plant sends a chemical signal - flavonoids - rhizobial cells produce their own Nod signal to indicate it's the right partner for mutualism - plant curl it's root into a "shepherd's crook" so that the bacteria can infect that point - bacteria infects through the infection thread made of cellulose - bacteria divide along this thread and enter the location where the nodule will be produced
37
how do Rhizobium benefit plants
many of the cell differentiate into nitrogen-fixing machines and they fix dinitrogen (N2) into ammonia which the plants can use (may also directly supply amino acids)
38
how do plants benefit rhizobial cells
they provide photosynthates which serve as a source of energy and electrons to produce ATP in the rhizobia; the plant also protects the rhizobia from being exposed to free oxygen
39
what is leghemoglobin
works similarly to hemoglobin, carries oxygen to rhizobia to ensure sufficient oxygen for respiration and minimal free oxygen
40
what is the main feature of enteric bacteria
many bacteria in this group and pathogenic and associated with food-borne illnesses
41
which group are enteric bacteria part of
found withing the Gammaproteobacteria, within the Enterobacteriaceae family
42
what are enteric bacteria's relationship with oxygen
they are facultative anaerobes
43
what does it mean to be oxidase negative
these bacteria lack cytochrome c oxidase, enteric bacteria have cytochrome A instead
44
what type of flagella do enteric bacteria have
peritrichous flagella
45
where do enteric bacteria live
many live in soils and are plant saprophytes (consume dead plant material), some live in the guts of mammalian hosts (referred to as coliforms)
46
what are some of the basic features of enteric bacteria
- rod-shaped - Gram-negative - non-spore forming - ferment lactose and produce acid and gas in the the process
47
what do multiple coliforms indicate
fecal contamination
48
what does the abundance of enteric bacteria indicate
possible presence of pathogens
49
what are major features of Deltaproteobacteria
- Gram-negative - aerobic
50
describe Bdellovibrio
- bacteria that prey on other Gram-negatives - seek a host to penetrate the periplasmic space - produces hydrolytic enzymes to degrade the cell wall of the prey - consume the cytoplasm - septates & divides into 3-6 progeny cells - obligate parasite - infects b/w 2 and 4 hours
51

BIOL 240 (12 decks)

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