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Microbiology > Chapter 7 > Flashcards

Chapter 7 Flashcards

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Biology 101 flashcards
1
Q

metabolism of microorganisms can be used to classify them into 4 groups, what are they

A
  1. oxygen requirement (aerobes= require oxygen for growth ex: Legionella, anaerobe= oxygen is not required for growth (Clostridium), Facultative aerobe: oxygens is not required, but enhance growth rate (E.Coli)
  2. source of energy, electron and carbon (chemicals = chemotroph, light= phototroph)
  3. electrons (organic compunds (glucose)= organotroph, inorganic compunds (H2S) = lithotroph where lito=rock)
  4. carbon (organic compunds (glucose)= heterotroph, inorganic compunds (CO2)= autotroph)
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2
Q

how de we separate chemotroph (the ones that use a chemical source of energy

A
  • organic chemicals (glucose, acetate…) = chemoorganotrophs (ex: Escherichia Coli)
  • inorganic chemicals (H2, Fe+,H2S…) = chemolithotrophs (ex: thiobacillus thiooxidans)
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3
Q

one example of phototrophs

A

rhodobacter capsulatus

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4
Q

in photoheterotrophy and photoautotroph, where come the electrons for the electran transport

A
    • both source of energy is light
      1. photohetetroph: come from organic compunds
      2. autotroph: come from H20 (oxygenic) or H2S (anoxigenic)
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5
Q

give the energy source, the electron donors, the carbon source and one example of:

  1. chemoorganoheterotroph
  2. chemolithoheterotroph
  3. chemolithoautotroph
A
  1. organic chemical, organic chemicals, organic chemical, ex: fungi/animal/protozoans
  2. inorganic chemical, inorganic chemical, organic chemicals, ex: limnobacter thooxidans (also able of chemoorganotrophy)
  3. inorganic chemicals, inorganic chemicals, CO2, ex: nitrifying bacteria, sulfur bacteria
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6
Q

give the energy source, the electron donors, the carbon source and one example of:

  1. photoheterotroph
  2. photoautotroph
A
  1. light, organic/inorganic chemicals, organic chemical, ex: purple nonsulfur bacteria
  2. light, inorganic chemicals, CO2, ex: algae/cyanobacteria/purple sulfur bacteria/ green sulfur bacteria
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7
Q

some aspects of chemohetetrophs

A
  1. glucose= glycolysis + TCA cycle + Respiratory chain= ATP
    glucose= cell material
  2. not all the environment contains oxygen and glucose so alternative = fermentation anaerobi respiration where there is the use of other terminal electron acceptors than oxygen. The respiratory chain has specific cytochromes and proteins to allow the use of specific terminal electron acceptors
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8
Q

the higher you are in the redox tower (the more negative is the Eo), the higher will be your tendency to give or accept electrons

A

to give electrons (the more negative is the Eo, the bigger is the tendency to give electrons)
** oxygen is the last one at the end because it’s the down that as the biggest tendency to accept electrons (the most positive)

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9
Q

which one is the best electron acceptor between nitarte, oxygen and fumarate

A

oxygen is better than nitrate and this one is better than fumarate
(the fumarate is the one that is the most negative, so less tendency to accept electrons)

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10
Q

what is denitrification

A

NO, N2O and N2 are gases, and as such, they are lost from the environment and this process is called denitrification
it is the conversion of the azote in nitrate into gases such as N2O or NO by bacteria

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11
Q

one benefit of denitrification and one disadvantage

A
  • benefical fro sewage treatment, to remove nitrate, which can stimulate algae growth in receiving water
  • loss of nitrate to the atmosphere is detrimental to agricultural process; plant uses nitrate as a source of nitrogen
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12
Q

denitrification: order of the transformation starts from nitrate to N2

A

nitrate (NO3-), nitrite (NO2-), nitric oxide (NO), nitrous oxide (N2O), dinitrogen (N2)

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13
Q

which comounds is the most common terminal electron in anaerobic respiration

A

nitrogen compunds

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14
Q

what Desulfovibrio can use as a terminal electron acceptor and as electron donor

A
  • it can use sulfate (SO4 2-) or sulfite (SO3 2-) as terminal electron acceptor
  • it can use an organic coumpund (lactate) or an inorganic compund (H2) as an electron donor but when lactate is used additional ATP is producefuroma
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15
Q

Desulfuromonas use what as an electon acceptor and as an electron donor

A
  • it uses sulfur (S0) as terminal electron acceptor and acetate, ethanol and other organic compunds as electron donors
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16
Q

what is the phenomenon when you break up the lactate to create ATP

A

it is substrate-level phosphorylation (since there is no oxygen, it can not be oxidative phosphorylation)

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17
Q

characteristics of H2S

A

rotten egg smells, can turn mud flats black due to the formation of metal sulfides

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18
Q

why pigment diversity has ecological significiance and what are the wavelenghts of absorption of the green bacteria, cyanobacteria and purple bacteria + what are the sediments

A

because they don’t have to compete for light since the absorption is made at different wavelenghts

  • green bacteria: 740nm
  • cyanobacteria: 680nm, O2
  • purple bacteria: 830nm
    sediments: chemoheterotroph and chemoautotroph
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19
Q

how are arrange chlorophyll or bacteriachlrophyll molecules

A

they are arranged in photocomplexes containing other photosensitive pigments and proteins but only a small farction of the pigments participate direclty in the photosynthesis reaction: the pigments in the reaction center (ex: P680,P700,P840)
- the pigments that surrunded the reaction center act as antennae to harvest light (LH) and funnel the energy to the RC

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20
Q

what are caotenoids + its role

A

they are hydrophobic, light-sensitive pigments firmly embedded in the photosynthetic membrane
their primarly role is to protect the system against bright light, which may lead to production of toxin forms of oxygen

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21
Q

what are phycobilins and their role

A

it forms complexe with proteins that are the main light-harvesting systems in Cyanobacteria: phycobilisomes. They harvest light of other wavelenghts than chlorophyll

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22
Q

site of photosynthesis in Eukarya

A

plants, algae: in the chloroplast. The chlorophylls are attached to the membrane of the thylakoid

23
Q

where the proton motive force is generated in chloroplast + characteristics of stroma and lumen or intrathylakoid space

A
  • the pmf is generated acroos the thylakoid membrane
  • stroma: alkaline, negative
  • intrathylakoid space or lumen: acidic (pH=4), positive
24
Q

bacteria, photosynthetic pigments are integrated into internal membranes (3) + examples for each

A
  1. in the cytoplasmic membrane itself: heliobacteria
  2. in intracytoplasmic membrane: purple bacteria (vesicles, lamella)
  3. in thylakoid membrane (cyanobacteria, prochlorophytes)
  4. chlorosomes: present in green sulfur bacteria (Chlorobium) and green non sulfur bacteria (Chloroflexus)
25
Q

which bacteri may be the ancestor of eukaryotes (plants and algaes) and why

A

cyanobacteria and prochlorophytes because there photosynthetic pigments are in their thylakoid membrane which is similar to eukaryotes

26
Q

2 characteristics of chlorosomes

A
  • they are giant antenna systems: Bchl, c, d, e are arranged in rod like arrays in the chlorosome and transfer light energy to Bchl a in the reaction center (RC)
  • it is the best system to capture energy at very low light intensity. Green bacteria can colonize niches of very low light intensity, such as deep, anoxic aquatic habitat
27
Q

in E.Coli, for the aerobic respiration and nitrate reduction, what are the electron donor, electron acceptor and how many protons are generated

A

aerobic:

  • NADH provides the electrons
  • O2 is the terminal electron acceptor
  • 8 H+ are generated to create ATP by ATPase

nitrate reduction:

  • NADH provides the electron
  • nitrate (NO3-) is the terminal electron acceptor
  • 6 H+ are generated
28
Q

why Pseudonomas can generate 8 H+ like aerobic respiration even if the final electron acceptor is the nitrate

A

because when you can do all the transformation (have all the enzyme complexes that permit the complete denitrification) you can create 8 H+

29
Q

anoxygenic (one type of phototrophs) 2 examples, electron donors, what generates pmf, what do NADH

A
  • purple and green bacteria
  • sulfur (S0) and hydrogen sulfite are the electron donors
  • NADH is reduce in the electron transport chain and it will fix the carbon of CO2 into a complex organic compund (create sugar)
  • energy for the pmf is the light so ATP will be create and will be use to fix carbon into sugar
30
Q

oxygenic (one type of phototroph) 3 examples, electron donors, what generate pmf,

A
  • cyanobacteria, algae, green plants
  • water is the electron donor
  • oxygen will be synthesized by the photosynthesis
  • light is the energy for pmf
  • ATP and NADH will be use to fix carbon into complex sugars
31
Q

______ pigments are required for photosynthese

A

light-sensitive pigments

32
Q

there is a diversity of ______, each with a different ______ + give one example

A

pigments
absorption spectrum
- example: bacteriochlorpohyll a is a type of chlorophyll a

33
Q

why chlorophyll a is green

A

because in its absorption spectrum, they can absorb blue or red but they can’t absorb green so they reflect it

34
Q

2 examples of phycobilisme and they are embedded in what

A

allophycocyanin and phycocyanin

embedded in the thylakoid membrane

35
Q

general steps of anoxygenic phosphorylation for purple bacteria (from light to ATP)

A
  1. light will hit the photocomplex and this will excited the electrons
  2. electrons will move to the electron transport chain and will then create a pmf that will permit the generation of ATP through ATPase
    we call this photophosphorylation
36
Q

in purple bacteria, why don’t we need electron donor

A

because it is a cyclic photophosphorylation: electron cycles thourgh the system (they will always be excited by light) so it produces pmf for ATPase

37
Q

what are the sources of electron for purple sulfur and purple nonsulfur (need electron to reduce NAD+)

A

purple sulfur: H2S (photoautotrophs)

purple nonsulfur: succinate (organic compunds, photoheterotrophs, also used as carbon source)

38
Q

in purple bacteria, energy of P870 is not enough to reduce NAD+, so what happen

A

NADH will be reduce by reverse electron flow:

  • pmf supply energy (less ATP will be produced)
  • e- are transferred to complex 1 (NADH dehydrogenase) which reduce NAD+ to NADH (involves reversal of its normal functions, most enzymes are reversible)
    consequence: since wie have to use some pmf for the creation of NADH, it creates a very low yield
39
Q

characteristics of the periplasm and the cytoplasm

A

periplasm: positive, acid because of the accumulation of H+
cytoplasm: alkaline, negative

40
Q

what are the elctron source in the anoxygenic photosynthesis for green sulfur bacteria (3)

A

H2S (hydrogen sulfure), S (sulfur), or S2O3 2- , so they will be oxidized to reduce NAD+ in NADH
** this process where we reduce NADH by oxidizing H2S runs in parallel with the pmf that creates ATP

41
Q

2 organism that do oxygenic photosythesis + what are the electron dnor, what happened, what is create

A
  • plants and algae
  • use light energy to oxidize H20: H20 = O2 + 2H+ + 2e
  • water is the electron donor and oxygen will be form
  • electrons will be excited by the light, will create a pmf that will allow the ATPase to create ATP and NADP+ will be reduce
    ** cyanobacteria= cytoplasm
    chloroplast= stroma
    *** the pmf is generated in the thylakoid membrane
42
Q

what are the two options of pattern for oxygenic photosynthesis (two options of pathway)

A
  1. noncyclic photophosphorylation: when you don’t have enough NADPH in your body, a pair of e- is used to produce pmf and NADPH
  2. cyclic photophosphorylation: when the quantity of NADPH (reducing power) is enough (don’T need to produce more, an electron source), electrons return to cytbf
43
Q

what is different in anoxygenic photosynthesis for some cyanobacteria

A

H2S inhibits the PS2

  • H2S is the source for electron
  • cyclic phosphorylation: electron from p700 creates a pmf that will activate the ATPase to create ATP
  • e- from H2S= transport chain= NADPH
44
Q

what is the major difference between denitrfying and nitrifying batceria

A

denitrifying: use nitrate as electron acceptor
nitrifying: organisms that used inorganic nitrogen compunds (nitrogen (NO2-) or ammonia (NH3) as electron donors

45
Q

what are the 2 groups of organisms that that carry out nitrification (the complete oxidation of ammonia to nitrate) and in which conditions nitrification happes

A
  1. Nitrosomonas oxidizes ammonia to nitrite
  2. Nitrobacter oxidizes nitrite to nitrate
    * * nitrite is toxic, nitrate (NO3-) is a better source of nitrogen for plants
    - nitrification requires O2 (aerobic respiration)
46
Q

what happens in the process of nitrosomonas (oxidize ammonia to nitrite) + why it is a low yield + how does NADH is produce

A
  • electron acceptor = O2
  • very low yield because ammonia monooxygenase needs 2e- from the electron transport chain to oxidize ammonia, for every 4 e- generated from oxidation of NH3 to NO2-, only 2 reach the Cyta3, the proton pump
  • NADH is produce by reverse electron flow. Q=Complex 1 of the respiratory chain, pmf is the energy source
47
Q

what happens in the process of nitrobacter (oxidize nitrite to nitrate)

A
  • electron acceptor: O2
  • like nitromonosomas, low yield, because 2 e- from the pmf are used to create NADH instead of using in for ATP (so NADH is create by reverse e- flow)
  • NXR (nitrite oxidoreductase) is the enzyme that oxidize nitrite to nitrate
48
Q

proces to create energy for sulfur bacteria

A
  • energy source: H2S, S0 (sulfur), S2O3 2-
  • electron acceptor : oxygen
  • NADH are produce by the reverse e- flow
  • it will produce SO4 2- and protons (sulfuric acid which is responsible for acidic run-off from coal mines)
  • ** oxidation of H2S occurs in steps, the first step yielding S0, which is stored in cell inclusions
49
Q

where methanogens are found (4)

A

found in marshes, anaerobic sediments, landfills sites, intestinal tract of animals

50
Q

difference between methanogens and methanotrophs

A

methanogens produce methane and they are strict anaerobes whereas methanotrophs are the opposite: use methane as the electron donor and need oxygen as the electron acceptor

51
Q

2 different ways of methanogens

A

can use acetate or hydrogen and CO2 but in each cases, methane is create

52
Q

methanotrophs are present where

A

in aerobic zones overlying anaerobic sediments

53
Q

fixation of CO2 (calvin cycle), give examples of organisms that can do that + where are the enzymes for prokaryotes and eukaryotes

A
  • photoautotrophs: algae, cyanobacteria,purple sulfur, green sulfur bacteria
  • chemoautotrophs: nitrifying bacteria, sulfur bacteria, some methanogens
  • eukaryotes: enzymes in the stroma of chloroplast
  • prokaryotes: enzymes in the cytoplasm
54
Q

important concept of calvin cycle

A

CO2 is used to create complex organic compunds and then cam be used for biomass
- ATP and NADH are needed a lot in the cycle

Microbiology (25 decks)

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