3.2 Metabolic diversity Flashcards

1
Q

describe general catabolism in chemoorganotrophs
- ie what pathways? (schéma!)

A

from glucose:
- glycolysis to 2 pyruvates –> than TCA cycles (intermediates go towards anabolism) –> 6 CO2
- glycolysis and TCA produce ATP (substrate level phos.) + [H] which reduce NAD+ into NADH
- NADH goes to respiratory chain, produces pmf which converts ADP to ATP (oxidative phosphorylation

  • glucose can also to pentose phosphate pathway and make NADPH (reducing power for anabolism)
  • can also form many C3, C4, C5, C6, C7 substances –> anabolism
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2
Q

metabolism of microorgs can be used to classify them into groups:
1. __________ requirement: 3 types
2. classify by 3 different things

A

OXYGEN REQUIREMENT
- aerobe: require O2 for growth (ie Legionella)
- anaerobe: oxygen NOT required for growth (Clostridium –> cannot live in presence of O2)
- facultative aerobe: O2 is not required but enhances growth rate (ie E.coli = versatile)

ENERGY: chemicals (chemotrophy) OR light (phototrophy)

ELECTRONS: organic compounds (ie glucose) (organotrophs) OR inorganic compounds (ie H2S) (lithotrophs)

CARBON: organic compounds (ie glucose) (heterotrophy) or inorganic compounds (ie CO2) (autotrophy)

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3
Q

describe what source of energy, electrons and carbon:
CHEMOORGANOHETEROTROPHS
CHEMOLITHOHETEROTROPHS
CHEMOLITHOAUTOTROPHS
PHOTOHETEROTROPHS
PHOTOAUTOTROPHS

  • do they do aerobic or anaerobic respiration or photosynthesis?
  • electron acceptors?
A

CHEMOORGANOHETEROTROPHS
- organic chemicals as source of E
- organic compounds as electron source/donor & carbon source
- both aerobic and anaerobic
- S^0, NO3-, SO4^2-, organic e- acceptors, O2
*ie protozoa, funghi, animal cells, most nonphotosynthesis bacteria

CHEMOLITHOHETEROTROPHS
- inorganic chemicals as source of E
- inorganic compounds (H2, H2S, Fe2+, NH4+) as electron source/donor
- organic chemical as carbon source
- both aerobic and anaerobic
- S^0, NO3-, SO4^2-,O2
*ie limnobacter thiooxidans

CHEMOLITHOAUTOTROPHS
- inorganic chemicals as source of E
- inorganic compounds (H2, H2S, Fe2+, NH4+) as electron source/donor
- inorganic chemical (CO2) as carbon source
*ie nitrifying bacteria, sulfur bacteria

PHOTOHETEROTROPHS
- light as E source
- organic or inorganic compound as e- donor
- organic chemical as C source
- e- donor: H2O, H2S
*purple non-sulfur bacteria

PHOTOAUTOTROPHS
- light as E source
- inorganic chemical as e- donor
- CO2 as C source
*ie algae, cyanobacteria, purple sulfur bacteria, green sulfur bacteria

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4
Q

what type of metabolism/energy, electron and carbon source/donor do they have:
SULFUR BACTERIA
PURPLE NONSULFUR BACTERIA
PURPLE SULFUR BACTERIA

A

SULFUR BACTERIA
- chemolitoautotroph:
- E: inorganic chemical
- e- donor: inorganic chemical
- C: CO2

PURPLE NONSULFUR BACTERIA
- phototheretotroph
E: light
e- donor: organic or inorganic chemical
C: organic chemical

PURPLE SULFUR BACTERIA
- photoautotroph
E: light
e- donor: inorganic chemical
C: CO2

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5
Q

what happens when your environment doesn’t contain oxygen? –> which type of respiration? explain how

A

anaerobic conditions: fermentation or anaerobic respiration

anaerobic respiration: used of other terminal electron acceptors than O2
- respiratory chain has specific cytochromes and proteins to allow use of specific terminal electron acceptors

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6
Q

which will make a bacteria/cell grow faster? –> put them in order from slowest to fastest (EXAM!)

  • sulfate respiration (SO4^2-)
  • denitrification
  • aerobic respiration
  • nitrate respiration (NO3-)
  • sulfur respiration
A

higher up you’re on the tower, the worst/least amount of E you can get!

  • sulfur respiration (highest up = lowest E)
  • sulfate respiration
  • nitrate respiration
  • denitrification
  • aerobic respiration (lowest on tower)
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7
Q

DENITRIFYING BACTERIA
- what are its sources of carbon, energy and electrons
- what are the most common terminal e- acceptors under anaerobic conditions
- what is denitrification? –> detrimental to what processes? vs beneficial for what?

  • describe 4 reactions from nitrate to dinitrogen. which are gases?
A
  • organic compounds!
  • nitrogen compounds!
  • NO, N2O and N2 are gasses –> lost to the environment = denitrification
  • loss of nitrate to atmosphere = detrimental to agricultural processes; plants use nitrate as a source of nitrogen!
  • beneficial for sewage treatment to remove nitrate –> nitrate stimulates algal growth in receiving water

nitrate (NO3-) –> nitrite (NO2-) –> nitric oxide (NO) –> Nitrous oxide (N2O) –> dinitrogen (N2)

NO, N2O and N2 are gases

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8
Q

how many protons can they pump if O2 vs no O2 present
- E.coli VS pseudomonas

A

E. COLI
- O2 as final e- acceptor –> 8 H+
- NO3- as final e- acceptor –> 6 H+ (less protons bc NO3- is higher on the tower) (from NO3- to NO2-)

PSEUDOMONAS:
- 8 H+ for O2 or NO3- (but very complicated denitrification system! –> from NO3- to N2)

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9
Q

SULFATE AND SULFUR REDUCTION
- source of C, E and e-?
- desulfovibrio can use (2) as terminal e- acceptor
- desulfovibrio can use (2) as an electron donor. when _________ is produced, more ATP is produced
- desulfuromonas uses WHAT as terminal e- acceptor and use (3) as e- donors
- what gives rotten egg smell? –> what doe sit also do?

A
  • organic copounds!
  • sulfate (SO4^2-) or sulfite (SO3^2-)
  • organic (lactate) or inorganic (H2) as e- donor –> lactate! –> strip e- from lactate to pump H+ across membrane!
  • use sulfur (S^0) as terminal e- acceptor and use acetate, ethanol and other organic compounds as e- donors
  • H2S (sulfide) = egg small –> can turn mud flats black due to formation of metal sulfides
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10
Q

what are sources of sulfur compounds in environment? (4)

A
  • volcanoes
  • deep sea
  • mining
  • industry

H2S, S, S2O3^2-, SO4^2-, SO3^2-

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11
Q

PHOTOTROPHS
- all use ______ as E source
- who uses CO2 as C source? vs glucose/organic C?
- which bacteria as anoxygenic? vs oxygenic?
- what substance gives e- to make NADH (ie what substance is the reducing power) for anoxygenic vs oxygenic?
- what is something special about anoxygenic?

  • what is used to generate pmf?
A
  • light!
  • photoautotrophs: CO2 VS photoheterotrophs: organic C

ANOXYGENIC:
- purple and green bacteria
- H2S (sulfide) and S^0 = e- donor! –> reduced to SO4^2-
- sulfate and sulfur reducers (ie reduce sulfate and sulfur to sulfide (H2S) allow anoxygenic phototrophs to have reducing power! so they live happily together!
OXYGENIC:
- cyanobacteria, algae, green plants
- H2O = e- donor –> reduced to 0.5 O2

  • light energy!
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12
Q
  • _____A______ are required for photosynthesis?
  • how to differentiate ____A______?
A

light-sensitive pigments!
- each has a different absorption spectrum! and a different peak!
- ie chlorophyll a: peak at 680nm
- bacteriochlorophyll a: peak at 805 and 870nm

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13
Q

you have a sediment
- light shines on its top surface –> than there is a layer of green, than of purple, than sediments

  • explain what type of bacteria are present on the sediment
A

GREEN LAYER:
- green bacteria (740 nm) + cyanobacteria (680nm, O2) –> both cannot absorb green, that’s why they look green
PURPLE LAYER:
- purple bacteria (830 nm) –> absorb wavelength that goes through the green rock
SEDIMENTS:
- there’s H2S produced by sulfate reducers –> used by phototrophs as reducing power
- also chemoheterotrophs and chemoautotrophs (don’t need light!)

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14
Q
  • Chlorophyll or bacteriochlorophyll molecules are arranged in _________
    containing (2) (not always).
  • do all pigments participate in photosynthesis?
  • pigments that surround the _____________ act as ___________ to harvest light (LH) and ________ the energy to WHERE –> explain
A
  • in photocomplexes –> other photosensitive pigments and proteins (not always).
  • ponly a small fraction of the pigments participate directly in the photosynthesis reaction: the pigments in the reaction center (RC). Ex. P680, P700, P840.
  • that surround reaction center act as antennae (light harvesting complex) –> funnel energy to the RC

*light harvesting complexes “exchange” the energy until one has enough high energy electron to become the reaction center (RC)
*RC –> than goes to electron transport system –> pmf to make ATP

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15
Q

Carotenoids are ___________, _______ –
sensitive _________ firmly embedded in the _____________ membrane.
- primary role?

Phycobilins form complexes with
_________ that are the main _________ in which bacteria? –> complex is called what?
- do they harvest light of same wavelengths than chlorophyll?

A
  • hydrophobic, light sensitive pigment, embedded in photosynthetic membrane
  • protect the system against bright light, which may lead to production of toxic forms of oxygen.
  • proteins that are the main light-harvesting systems in cyanobacteria –> phycobilisomes
  • harvest light of other wavelengths than chlorophyll –> complement each other yay!
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16
Q

SITE OF PHOTOSYNTHESIS
- in plants, algae (eukaryotes)?
where are chlorophylls? where is the pmf?

  • in bacteria: where are photosynthetic pigments? –> 4 types ish
A

PLANTS/ALGAE:
- chloroplast!
- chlorophylls (+ light harvesting complex) are attached to membrane of thylakoid
- pmf is generated across thylakoid membrane: stroma (alkaline, negative) and intrathylakoid space (acid, positive bc H+)

BACTERIA:
- integrated into internal membranes!
a) in cytoplasmic membrane itself: heliobacteria
b) in intracytoplasmic membrane systems: purple bacteria (vesicles, lamellae) –> have vesicles!!!
c) in thylakoid membrane: cyanobacteria, prochlorophytes –> have thylakoid but no chloroplast
d) chlorosome: present in green sulfur bacteria (chlorobium) and green nonsulfur bacteria (chloroflexus)

17
Q

what are chlorosomes?

  • it is the best photosystem to do what?
  • present in which bacteria?
A

giant antenna systems (proteins that hold lots of chlorophyll): Bchl c,d,e are arranged in rod like arrays in the chlorosome and transfer light energy to Bchl a in the reaction center

  • it is the best photosystem to capture energy at very low light intensity
  • present in green sulfur bacteria (chlorobium) and green nonsulfur bacteria (chloroflexus)
  • green bacteria can colonize niches of very low light intensity, such as deep, anoxic aquatic habitat
18
Q

anoxygenic photosynthesis: purple bacteria
- describe how ATP is produced

  • which side of membrane is acid/alkaline and positive/negative?
A
  • through cyclic photophosphorylation!: light is energy to renergize electrons! but e- are recycled!
  1. light shines on the membrane: antennaes funnel E to chlorophyll
  2. chlorophyll P870 (reaction center) is a good e- acceptor, until it accumulates so much energy that it becomes a good e- donor!
  3. once chlorophyll is a good e- donor (high on tower) –> gives e- to Q + H+ from cytoplasm –> shuttle e- to bc1 and pumps 2 H+ across membrane
  4. eventually, e- are shuttle back to P870 (low energy state now) = recycling of electrons!
  5. pumped protons across membrane create pmf which powers ATPase to make ATP!

periplasm/out = acid and positive bc H+ accumulation
cytoplasm = alkaline, negative

19
Q

anoxygenic photosynthesis: green sulfur bacteria
- describe how ATP is produced?
- 2 systems run in parallel?
- consequence? reducing power electron source?

A
  • cyclic photophosphorylation –> no need for e- donor, e- cycles through the system. produce pmf for ATP synthase (just like purple bacteria)
    1. PMF –> ATP (electrons cycle and are recycled)
    2. reduce NAD+, oxidize H2S
  • reducing power = need e- donor –> electrons are used to reduce NAD+ to NADH by ferredoxin –> because NAD+ steal e- to become NADH –> electron source becomes = oxidation of reduced sulfur compounds (H2S, S, S2O3)
20
Q

ANOXYGENIC PHOTOSYNTHESIS: purple bacteria
- need electron source to do what (A)?
- that source is what for purple sulfur vs purple nonsulfur

  • in purple bacteria, is energy of P870 enough to do (A) –> what happens then?
  • consequence?
A
  • to reduce NAD+!
    purple sulfur: H2S
    purple nonsulfur: succinate (organic compounds, photoheterotrophs, also used as a carbon source)
  • NOT enough to reduce NAD+ (bc too low on the tower)
  • NADH is produced by REVERSE ELECTRON FLOW
    1. pmf supply energy (less ATP will be produced)
  • pump so much H+ so that e- dont go to cytbc1 (bc pipe is blocked) –> so e- go up the tower to reduce NAD+ (ie pipe bursting)
    2. electrons are transferred to complex 1 of respiratory chain (NADH dehydrogenase) which reduces NAD+ to NADH –> involves reversal of its normal function –> most enzymes are reversible
  • very low yield! many complexes will produce pmf, a few will produce NADH consuming pmf in the process (bc it requires a lot of energy to maintain pmf so high = bacteria will grow slowly)
21
Q

what type of photosynthesis does purple bacteria vs green sulfur bacteria?

A

PURPLE bacteria; anoxygenic photosynthesis –> cyclic photophosphorylation + reverse electron flow

GREEN SULFUR bacteria: anoxygenic photosynthesis –> cyclic photophosphorylation

22
Q
  • sulfate reducer: sulfate = electron what?
  • denitrifier: nitrate = electron what?
  • in nitrate and sulfate reducers: how do you make NADPH for anabolic reactions?
A
  • electron acceptors!
  • electron acceptors!
  • using pentose phosphate pathway!
23
Q
  • what type of photosynthesis does algae and cyanobacteria do?
  • use what energy to oxidize WHAT?
  • explain steps ish (5)
A
  • oxygenic photosynthesis –> noncyclic photophosphorylation! pair of e- is used to produce PMF and NADPH
  • light energy to oxidize H2O
    H2O –> O2 + 2H+ + 2e-
    1. H2O donates electron to P680 –> light energizes electron so they increase E (in photosystem II)
    2. electrons (high energy now) go down electron transfer chain) –> through quinone pool –> pumps H+ = makes PMF
    3. electrons go from photosystem II to photosystem I (a bit higher E than PSII), where light energizes electron
    4. e- high energy now (higher than at 2)) –> go down ETC –> quinone –> makes PMF
    5. e- fall down and produces NADH and NADPH

*PMF drives ATP synthase

24
Q

oxygenic photosynthesis of algae and cyanobacteria:
- is it cyclic?
- what happens when reducing power is sufficient for cell’s needs? (ie enough NADH)

  • better energy yield than purple and green bacteria?
  • source of electron?
A
  • usually noncyclic when electrons don’t come back to RC bc e- go to NADH VS
  • when enough NADH, e- return to cytbf (part of PSII) –> no need to e- source –> cyclic phosphorylation!
  • e- are then shuffled to PSI
  • yes!
  • water! –> produces H+ and O2 –> oxygenic phtosynthesis
25
Q

oxygenic photosynthesis: which side is alakaline/negative vs acid and positive?

A

thylakoid lumen = accumulation of H+ = acid and positive

cyanobacteria = cytoplasm, –> chloroplast stroma –> alkaline and negative

26
Q

what do some cyanobacteria have to do anoxygenic photosynthesis?
- source of e-?
- explain pathway steps (3 ish)

  • cyclic or noncyclic?
  • higher or lower yield than oxygenic photosynthesis?
A
  • because sulfide (produced by sulfide reducers) inhibits photosystem II! so only PS I left
  • oxidized H2S = electron source –> modified electron chain
  1. H2S donates e- to cytbf –> P700 of PSI
  2. light energizes electron –> goes down e- chain –> leads to the creation of PMF that drives ATP synthase
  • cyclic if e- goes back to cyt bf (if enough reducing power)
  • non-cyclic if NADPH accepts final electron
  • lower! bc less pmf bc only PSI
27
Q

what are chemoautotrophs?
- 2 examples
- electron acceptors?

A
  • primary producers (bc can fix C)
  • use inorganic compounds as source of E and e- + CO2 as carbon source
    1) nitrifying bacteria (nitrosomonas and nitrobacter)
    2) sulfur bacteria (thiobacillus
  • anaerobic: S^0, SO4^2-, NO3-
  • aerobic: O2
28
Q

NITRIFYING BACTERIA
- organisms that use WHAT (2) as electron donors –> which bacteria uses what?
- define nitrification
- what is a better source of N for plants?
- nitrification only occurs in what conditions?

  • what are the benefits if low low yield?
A
  • use inorganic N as e- donnors:
    a) one group (nitrosomonas) oxidizes AMMONIA to nitrite
    b) another group (nitrobacter) oxidizes nitrite to nitrate
  • nitrification = complete oxidation of ammonia to nitrate: NH3 –> NO2- –> NO3-
  • nitrate is a better source! nitrite is toxic
  • only in aerobic conditions! requires O2 bc nitrate is very low on tower –> O2 = only thing low enough to have enough difference to yield energy
  • use something that nobody wants, don’t need to compete with other organisms, happy/content how they are
29
Q

Nitrosomonas spp.
- final e- acceptor?
- ammonia monoxigenase needs # e- to oxidize ____________. supplied by WHAT?
- what is oxidized vs reduced?
- for every 4 e- generated from oxidation of NH3 to NO2- –> only # reach the cyt aa3, the proton pump
- NADH is produced by WHAT?
- high or low yield?

A
  • O2
  • 2e- to oxidize ammonia –> supplied by Q
  • ammonia is oxidized. O2 is reduced
  • 2 reach cytaa3
  • reverse electron flow! Q –> back to complex 1 of respiratory chain. PMF is the energy source!
  • very low yield! (2 ammonia = 1 ATP) –> 12 h for 1 duplication (vs 20min for E.coli)
30
Q

nitrobacter spp.
- final e- acceptor?
- what is oxidized vs reduced?
- NADH is produced through what?
- high or low yield

A
  • O2!
  • nitrite (NO2-) is oxidized. O2 is reduced
  • reverse electron flow! Q –> back to complex 1 of respiratory chain. PMF is the energy source!
  • very low yield
31
Q

SULFUR bacteria: thiobacillus sppl.
- source of e-?
- e- acceptor?
- produces (2) –> responsible for what?
- NADH is produced how?
- __________ oxidation occurs in steps, the first step yielding _____ –> stored in what?

A
  • H2S, S^0, S2O3^2- –> bacteria oxidizes sulfur compounds!
    (don’t confuse with sulfur reducers where sulfur compounds are electron acceptors!)
  • O2 = e- acceptor
  • SO4^2- and protons (sulfuric acid) –> responsible for acidic run-off from coal mines
  • by reverse electron flow
  • sulfide (H2S) oxidation –> yields S^0 –> stored in cell inclusions and used as energy/e- source if bacteria is starving
32
Q
  • what is a methanogen?
  • strict aerobes/anaerobes?
  • found where? (4)
  • 2 reactions
A
  • microbes that produce methane!
  • strict ANAEROBES! hate O2
    found in marshes, anaerobic sediments, landfill sites, intestinal tract of animals (ie cows)
    *don’t do fermentation or respiration!

source of e- and E: H2 and CO2
4 H2 + CO2 –> CH4 + 2H2O + E
CH3COOH (small organic acids) –> CH4 + CO2 + E

33
Q

what are methanotrophs? are they chemoorganotrophs or chemolitotrophs?

  • are strict aerobe/anaerobe?
  • use what as source of C, E and e-?
  • present where?
  • reaction
A

microbes that burn methane! neither! bc methane is not organic (bc no O2)

  • strict AEROBE!
  • use CH4 as source of C, E and E (strip e- from CH4 –> e- go through ETC –> produce PMF –> ATPase)
  • present in aerobic zones overlying anaerobic sediments (where methanogens live)

CH4 + 2O2 –> CO2 + 2H2O + E

34
Q

fixation of CO2 –> what cycle?
- name photoautotrophs that do it
- name chemoautotrophs that do it

  • where are enzymes found in eukaryotes vs prokaryotes?
  • which enzyme?
  • how much ATP and NADH do you need for 1 calvin cycle?
A
  • CALVIN cycle!
  • photoautotrophs: algae, cyanobacteria, purple sulfur and green sulfur bacteria
  • chemoautotrophs: nitrifying bacteria, sulfur bacteria, some methanogens
  • eukaryotes: stroma of chloroplast
  • prokaryotes: cytoplasm

ribulose biphosphate carboxylase! –> convert 5C into 2 x 3C

  • 12 NAD(P)H and 18 ATP –> need lots of energy and reducing power!