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Introductory Microbiology > Metabolic diversity -1 midterm > Flashcards

Metabolic diversity -1 midterm Flashcards

1
Q

What are three groups that organisms can be divided according to their oxygen requirement and the examples of each

A
  • Aerobes: require oxygen for growth (Legionella)
  • Anaerobe: oxygen is not required for growth (Clostridium)
  • Facultative aerobe: oxygen is not required but enhances growth rate (E.coli)
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2
Q

If the organism is using chemicals as a source of energy, he is called___, and if light ___

A

Chemotroph

Phototroph

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3
Q

If the main source of electrons for the organism is ___, then he is organotroph

And if ___, it is called lithotroph

A

Organic compounds

Inorganic compounds

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4
Q

Two groups of organisms, depending on what source of carbon they are using

A

Heterotroph: organic molecules
Autotroph:Inorganic molecules

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5
Q

What is the electron acceptor,electron donor,energy dource and carbon source in chemoorganoheterotroph and examples of these organisms

A

Source of energy: chemicals

Electrons are coming from organic molecules

Carbon source is organic molecules

Electron acceptor is O2 if aerobic respiration and S,NO3,SO4 and organic acceptors if anaerobic respiration

Examples:Protozoa, fungi, animals, most nonphotosynthetic bacteria

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6
Q

What is the electron acceptor,electron donor,energy dource and carbon source in chemolithoheterotroph and examples of these organisms

A

Source of energy comes from the sunlight (inorganic molecules)

Electrons are coming from inorganic molecules (H2,H2S,Fe)

Carbon source -organic compounds

Electron acceptor: if aerobic->O2
If anaerobic->S,SO4,NO3
Examples: few bacteria

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7
Q

What is the electron acceptor,electron donor,energy dource and carbon source in chemolithoautotroph and examples of these organisms

A

Source of carbon is coming from inorganic compounds(CO2)

The energy source comes from inorganic compounds

Electrons are coming from inorganic molecules (H2,H2S,Fe)

Electron acceptor: if aerobic->O2
If anaerobic->S,SO4,NO3

Examples: Nitrifying bacteria, sulphur bacteria

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8
Q

What is the electron acceptor,electron donor,energy dource and carbon source in photoheterotroph and examples of these organisms

A

The source of energy is sunlight
They are getting carbon from organic molecules
Electron donor is organic compounds
Examples: purple non-sulfur bacteria

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9
Q

Photoautophs get their electrons from and the examples of this organisms

A

H2O and H2S

Algae,cyanobacteria,purple sulphur bacteria, green sulphur bacteria

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10
Q

Two things that an organism can do if it is in aerobic conditions

A

Fermentation or anaerobic conditions

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11
Q

Oxygen is the best electron acceptor. What conclusion about respiration can we make out of that statement

A

If oxygen present, organism will prefer to use oxygen as an electron acceptor

Bit if unavailable, organisms can use also nitrate, sulfate , etc. as a final electron acceptor

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12
Q

What is denitrification?

A

Converting NO3- to N2

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13
Q

Electron donor is ___

A

The source of energy

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14
Q

What is the most common terminal acceptor under anaerobic conditions?

A

Nitrogen compounds

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15
Q

What do organic compounds provide in denitrifying bacteria and how they can be called then

A

The source of carbon, energy and electrons

Chemoorganoheterotrophs

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16
Q

What is denitrification

A

Loss of NO,NO2 and N2 as gases in the environment

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17
Q

Denitrification is good for ___ and bad for___

A

Denitrification is not beneficial for plants, because they use nitrate as a source of nitrogen

But denitrification is beneficial for sewage treatment, to remove nitrate , which can stimulate algal growth in receiving water

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18
Q

What is the full reduction of nitrate ?

A

Nitrate(NO3-)->nitrite(NO2-)->Nitric oxide (NO)->Nitrous oxide (N2O)->Dinitrogen(N2)

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19
Q

The examples of organism that does a full and partial reduction of nitrate

A

Full:Pseudomonas stutzeri

Partial( nitrate to nitrite): Escherichia coli

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20
Q

The difference in electron transport chain in e.coli under aerobic and anaerobic conditions

A

Aerobic respiration: * protons are pumped out into periplasm, NADH is the electron donor and oxygen is the electron acceptor

BUT
In nitrate reduction(anaerobic conditions) nitrate is the terminal electron acceptor and pump 6 protons in the periplasm

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21
Q

What advantage does pseudomonas have over e.coli under anaerobic conditions?

A

As pseudomonas can do a full reduction of nitrate , it pumps 8 electrons in the periplasm ,thus creating the same amount of ATP as with oxygen

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22
Q

In sulfate and sulfur reduction organic molecules serve as

A

The source of carbon, energy,electrons

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23
Q

Who does use sulfate (SO4) or sulfite (SO3) as a terminal electron acceptor

A

Desulfovibrio

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24
Q

Who does have the rotten egg smell and why

A

SO3 in Desulfovibrio is turned into H2S

Desulfuromonas
is using S+2H=->H2S

H2S =rotten egg smell and forms black presipitants

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25
Q

What is particular about Desulfovibrio?

A

It can use hydrogen gas or lactate as an electron donor.
If using lactate, it generates more ATP, because at first it metabolizes lactate and gets ATP from substrate level phosphorylation and the product of this reaction is H2 , which will enter the electron transport chain to give ATP

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26
Q

Two main groups in phototrophs

A

Purple and green bacteria
AND
Cyanobacteria,algae,green plants

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27
Q

What is anoxygenic

A

Purple and green bacteria do not produce oxygen as the result of their photosynthetic reactions

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28
Q

Where do purple and green bacteria get their electrons and NADH

A

H2S or from sulphur

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29
Q

What is used for fixation of carbon in purple and green bacteria

A

Electrons and the reducing power from H2S and S

And the energy comes from ATP that was generated by light

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30
Q

in phototrophs light energy is used to generate ___

A

proton motive force to make ATP

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31
Q

What is used for fixation of carbon in cyanobacteria,algae and green plants

A

Electrons from water

and ATP from sunlight

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32
Q

Why cyanobacteria,algae and green plants are called oxygenic

A

Because they are producing oxygen as the result of their photosynthetic reactions

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33
Q

What is required for photosynthesis

A

Light-sensitive pigments

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34
Q

What group imbeds chlorophyll in the membrane

A

Phytol

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35
Q

Why there are a lot of light-sensitive pigments

A

Because they absorb light at different wavelength

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36
Q

Chlorophyll a works best at ____, and bacteriochlorophyll a ___

A

360 nm and 805-870 nm

430 nm and 680 nm

37
Q

Why pigment diversity has ecological significance ?

A

Bacteria can live in communities, they do not need to compete for the space, because they use different pigments

38
Q

How are chlorophyll A an bacteriochlorophyll arranged?

A

The are arranged in photocomplexes
So in the center there is a small portion of photosynthetic organisms that participate directly in the photosynthesis.

The pigments that surround the reaction center are called antennae , they harvest the light and funnel the energy to the RC. They are also called light harvesting molecules

39
Q

What is the purpose of light-sensitive pigments in carotenoids?

A

They are firmly imbedded in the phytosynthetic membrane and they protect the system against bright light, which may lead to production of toxic forms of oxygen

40
Q

What are phycobilins(phycobilisome)

A

Phycobilisome consists of allophycocyanin and phycocyanin
They form complexes with proteins that are the main light-harvesting systems in cyanobacteria , imbedded in the thylokoid membrane

They harvest another wavelength of light, so they can be used together wth chloroplast to maximize the absorption

41
Q

Sites of photosynthesis in eukaryotes

A

Chloroplast

42
Q

The structure of chloroplast

A

Two membranes that has stroma space inside

It has thylokoid sacs that has chlorophylls attached to the membrane of the thylokoid

43
Q

The proton force in chloroplast is generated ( place)

A

Across the thylokoid membrane
In the stroma: alkaline, negative
Lumen or intrathylokoid space: acidic ( pH 4), positive

44
Q

Sites of photosynthesis in bacteria

A

Photosynthetic pigments are integrated into the internal membrane

45
Q

Three possibilities of internal membrane integration in bacteria and examples

A
  1. In the cytoplasmic membrane intself: heliobacteria
  2. In intracytoplasmic membrane systems( when the membrane fold in on itself) :purple bacteria(vesicles,lamellae)
  3. In thylokoid membrane :cyanobacteria, prochlorophytes
46
Q

The ancestor of the chloroplast

A

cyanobacteria lived in symbioses with some bacteria and eventually became chloroplast

47
Q

What is chlorosome

A

Green sulfur bacteria and nonsulfur bacteria have them

It is a giant antenna systems and the arrangement is a rod like arrays in the chlorosome and transfer light energy to the reaction center

This is the best photosystem to capture energy at very low light intensity- deep, anoxic aquatic habitat

48
Q

What is happening in the anoxygenic photosythesis in purple bacteria

A

When light hit reaction center, the electrons get excited and they move through the electron transport chain-> creation of pmf that allows for ATP to be generated ( photophosphorylation)

In the periplasm they have acidic environment and accumulation of H+ and in the cytoplasm , they have alkaline and negative charge

49
Q

Do purple bacteria need an electron acceptor ?

A

No to produce ATP, because the electron transport chain is cycled, beginning with the reaction center and ending in the reaction center . It is called Cyclic Photophosphorylation

50
Q

Electron source to reduce NAD+ in purple sulfur bacteria and in purple nonsulfur

A

Purple sulfur: H2S(photoautotroph)

Purple nonsulphur:succinate ( organic compounds, photoheterotrophs, also used as carbon source)

51
Q

In purple bacteria , energy of excited reaction center is not enough to reduce NAD+, so what is done for that reason and the consequence

A

NADH is produced by a reverse electron flow.

So some of pmf is used to take electrons back to NADH dehydrogenase-> less ATP is produced, low yield of energy

52
Q

How does green sulfur bacteria do photosynthesize

A

They so mostly the same thing as purple bacteria
Electron source :oxidation of reduced sulfur compounds

Some of electrons are used to regenerate NADH by ferredoxin

53
Q

What two systems run in parallel in green sulfur bacteria?

A

PMF->ATP(electron cycles)

Reduce NAD+, oxidize H2S

54
Q

Describe oxygenic photosynthesis

A

Algae and cyanobacteria use light energy to oxidize H2O to get H+ and electrons
Electrons->electron chain->NADPH
At the same time this movement will create a proton motive force that drives ATP synthase

55
Q

What is noncyclic photophosphorylation

A

When you need to regenerate NADPH, so the electrons are used to make NADPH and pmf

56
Q

What is cyclic photophosphorylation

A

When you have enough reducing power (NADPH), the electrons will just come back and generate pmf instead

57
Q

In cyanobacteria the part that is negative is __ and in chloroplast , this is ___

A

cytoplasm

stroma

58
Q

In oxygenic photosynthesis water comes___ and light comes___

A

From the thylokoid membrane side

In the stroma

59
Q

Anoxygenic photosynthesis happens in some

A

Cyanobacteria

60
Q

What happens during anoxygenic photosythesis in cyanobacteria

A

H2S inhibits photosystem 2 ( the beginning )
Oxidized H2S as electron source and modified electron chain that uses only PSI.
As there is no PSII, electrons from PSI go to electron chain->pmf -> ATP and this is cyclic photophosphorylation

electrons from H2S->electron chain-> NADPH

61
Q

Primary producers means

A

They can use inorganic compounds to make organic chemicals and use them as electrons

62
Q

Examples of chemolithoautrophs

A

Nitrifying bacteria and sulfur bacteria

63
Q

Two types of nitrogen compounds that organisms use as electron donors

A

Ammonia (NH3)

Nitrite (NO2)

64
Q

Who oxidizes ammonia to nitrite

A

Nitrosomonas

65
Q

Who oxidizes nitrite to nitrate

A

Nitrobacter

66
Q

The complete oxidation of ammonia to nitrate is called

A

Nitrification and is performed by a concerted action of Nitrobacter and Nitrosomonas

67
Q

Nitrite is ___, ___ is a better source of nitrogen in plants

A

Nitrite is toxic and nitrate is a better source of nitrogen for plants

68
Q

Nitrification occurs only in ___

A

Aerobic conditions

69
Q

The difference between nitrification and denitrifying-

A

Nitrification- bacteria uses nitrate or ammonia as electron donors

And denitrifying- using nitrogen substances as electron acceptors

70
Q

In nitrosomonas spp. final electron acceptor is

A

O2

71
Q

AMO is

A

ammonia mono oxygenase

72
Q

AMO needs ___ electrons to oxidize ammonia and the electrons are supplied by ___

A

2 electrons
Supplied by quinone
AMO needs some energy to get some energy out ( 2 electrons are needed to get 4 electrons from ammonia+ this 2 electrons are used for revesrse electron flow )

73
Q

As AMO needs some energy ,so

A

for every 4 electrons from ammonia , 2 are taken away, so only 2 electrons reach electron transport chain->low yield

NADH is produced by reverse electron flow( this is where 2 electrons are taken for)

74
Q

Nitrobacter spp. uses __ as a final electron acceptor

A

O2

75
Q

Nitrobacter spp. system is similar to

A 
nitrosomonas spp. 
Because NXR(nitrite oxidoreductase) similar to AMO uses reverse electron flow to generate NADH and uses some to get energy from NO2-> low yield
76
Q

Example of sulfur bacteria

A

Thiobacillus spp.

77
Q

Sulfur bacteria oxidize ___

A

Sulfur compounds ( H2S, S,S2O3)

78
Q

Thiobacillus spp. use __ as an electron acceptor

A

O2

79
Q

Sulfur bacteria produce __ and __ , that is a dangerous chemical

A

SO4- and protons ( sulfuric acid)

80
Q

In sulfur bacteria NADH is produced bu ____

A

A reverse flow of electrons

81
Q

Sulfide oxidation in sulphur bacteria occurs in ___, where ___ yields S0, which is ____

A

Steps
The first step
Stored in cell inclusions

82
Q

Methanogen do not tolerate ___

A

Oxygen, so strict anaerobes

83
Q

Methanogen produce

A

CH4

84
Q

Where we can find methanogens

A

In anaerobic sediments, landfill sites, intestinal tract of animals

85
Q

Two different types of methanogens

A

Use of hydrogen and CO2 to produce methane , energy and water

And the others use acetate to produce methane, CO2 and energy

86
Q

Methanotrophs are

A

Aerobes that use CH4 as a source of carbon and energy ( electron donor)
They produce CO2 and H20 and energy

87
Q

Fixation of Co2 happens in

A

Calvin cycle

88
Q

who does do fixation of CO2

A

Photoautotrophs:algae,cyanobacteria,purple sulfur and green sulphur bacteria
Chemoautotrophs:nitrifying bacteria, sulphur bacteria and some methanogens
Eukaryotes: enzymes in the stroma of chloroplast
Prokaryotes:enzymes in the cytoplasm

89
Q

Fixation of CO2 is

A

The process of getting sugars from CO2

Introductory Microbiology (21 decks)

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