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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
Q

where are nitrifiers found

A

in many different environments such as soils, sediments, and water columns; ammonia and nitrate oxidizers are often found growing in close association

26
Q

where are the key enzymes AMO and Nxr often found in nitrifiers

A

in internal membrane systems

27
Q

what is the metabolic category of Pseudomonads (and oxygen exposure)

A

aerobic chemoorganoheterotrophs

28
Q

what flagella do Pseudomonads have

A

polar flagella

29
Q

which group is very heterogeneous, being split up into Pseudomonas, Burkholderia, Ralstonia, and Comamonas

A

Pseudomonads

30
Q

why are some Pseudomonads flourescent

A

they produce a siderophore called pyoverdin which is used to acquire iron from a cell’s external environment

31
Q

what is the problem of nitrogen-fixing bacteria in environments with oxygen

A

the enzyme nitrogenase used for nitrogen fixation is irreversibly inactivated by oxygen

32
Q

how do nitrogen-fixing bacteria combat oxygen

A

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
Q

what are some features of Rhizobia

A
  • part of Alphaproteobacteria
  • aerobic Gram-negative rods
  • usually soil or plant associated
34
Q

how do Agrobacterium cause crown gall disease

A
  • 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
Q

what relationship do Rhizobium form

A

symbiotic relationships with leguminous plants

36
Q

how do Rhizobium form root nodules

A
  • 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
Q

how do Rhizobium benefit plants

A

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
Q

how do plants benefit rhizobial cells

A

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
Q

what is leghemoglobin

A

works similarly to hemoglobin, carries oxygen to rhizobia to ensure sufficient oxygen for respiration and minimal free oxygen

40
Q

what is the main feature of enteric bacteria

A

many bacteria in this group and pathogenic and associated with food-borne illnesses

41
Q

which group are enteric bacteria part of

A

found withing the Gammaproteobacteria, within the Enterobacteriaceae family

42
Q

what are enteric bacteria’s relationship with oxygen

A

they are facultative anaerobes

43
Q

what does it mean to be oxidase negative

A

these bacteria lack cytochrome c oxidase, enteric bacteria have cytochrome A instead

44
Q

what type of flagella do enteric bacteria have

A

peritrichous flagella

45
Q

where do enteric bacteria live

A

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
Q

what are some of the basic features of enteric bacteria

A
  • rod-shaped
  • Gram-negative
  • non-spore forming
  • ferment lactose and produce acid and gas in the the process
47
Q

what do multiple coliforms indicate

A

fecal contamination

48
Q

what does the abundance of enteric bacteria indicate

A

possible presence of pathogens

49
Q

what are major features of Deltaproteobacteria

A
  • Gram-negative
  • aerobic
50
Q

describe Bdellovibrio

A
  • 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
Q
A

BIOL 240 (12 decks)

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