Metabolic diversity -1 midterm Flashcards
What are three groups that organisms can be divided according to their oxygen requirement and the examples of each
- 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)
If the organism is using chemicals as a source of energy, he is called___, and if light ___
Chemotroph
Phototroph
If the main source of electrons for the organism is ___, then he is organotroph
And if ___, it is called lithotroph
Organic compounds
Inorganic compounds
Two groups of organisms, depending on what source of carbon they are using
Heterotroph: organic molecules
Autotroph:Inorganic molecules
What is the electron acceptor,electron donor,energy dource and carbon source in chemoorganoheterotroph and examples of these organisms
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
What is the electron acceptor,electron donor,energy dource and carbon source in chemolithoheterotroph and examples of these organisms
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
What is the electron acceptor,electron donor,energy dource and carbon source in chemolithoautotroph and examples of these organisms
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
What is the electron acceptor,electron donor,energy dource and carbon source in photoheterotroph and examples of these organisms
The source of energy is sunlight
They are getting carbon from organic molecules
Electron donor is organic compounds
Examples: purple non-sulfur bacteria
Photoautophs get their electrons from and the examples of this organisms
H2O and H2S
Algae,cyanobacteria,purple sulphur bacteria, green sulphur bacteria
Two things that an organism can do if it is in aerobic conditions
Fermentation or anaerobic conditions
Oxygen is the best electron acceptor. What conclusion about respiration can we make out of that statement
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
What is denitrification?
Converting NO3- to N2
Electron donor is ___
The source of energy
What is the most common terminal acceptor under anaerobic conditions?
Nitrogen compounds
What do organic compounds provide in denitrifying bacteria and how they can be called then
The source of carbon, energy and electrons
Chemoorganoheterotrophs
What is denitrification
Loss of NO,NO2 and N2 as gases in the environment
Denitrification is good for ___ and bad for___
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
What is the full reduction of nitrate ?
Nitrate(NO3-)->nitrite(NO2-)->Nitric oxide (NO)->Nitrous oxide (N2O)->Dinitrogen(N2)
The examples of organism that does a full and partial reduction of nitrate
Full:Pseudomonas stutzeri
Partial( nitrate to nitrite): Escherichia coli
The difference in electron transport chain in e.coli under aerobic and anaerobic conditions
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
What advantage does pseudomonas have over e.coli under anaerobic conditions?
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
In sulfate and sulfur reduction organic molecules serve as
The source of carbon, energy,electrons
Who does use sulfate (SO4) or sulfite (SO3) as a terminal electron acceptor
Desulfovibrio
Who does have the rotten egg smell and why
SO3 in Desulfovibrio is turned into H2S
Desulfuromonas
is using S+2H=->H2S
H2S =rotten egg smell and forms black presipitants
What is particular about Desulfovibrio?
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
Two main groups in phototrophs
Purple and green bacteria
AND
Cyanobacteria,algae,green plants
What is anoxygenic
Purple and green bacteria do not produce oxygen as the result of their photosynthetic reactions
Where do purple and green bacteria get their electrons and NADH
H2S or from sulphur
What is used for fixation of carbon in purple and green bacteria
Electrons and the reducing power from H2S and S
And the energy comes from ATP that was generated by light
in phototrophs light energy is used to generate ___
proton motive force to make ATP
What is used for fixation of carbon in cyanobacteria,algae and green plants
Electrons from water
and ATP from sunlight
Why cyanobacteria,algae and green plants are called oxygenic
Because they are producing oxygen as the result of their photosynthetic reactions
What is required for photosynthesis
Light-sensitive pigments
What group imbeds chlorophyll in the membrane
Phytol
Why there are a lot of light-sensitive pigments
Because they absorb light at different wavelength
Chlorophyll a works best at ____, and bacteriochlorophyll a ___
360 nm and 805-870 nm
430 nm and 680 nm
Why pigment diversity has ecological significance ?
Bacteria can live in communities, they do not need to compete for the space, because they use different pigments
How are chlorophyll A an bacteriochlorophyll arranged?
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
What is the purpose of light-sensitive pigments in carotenoids?
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
What are phycobilins(phycobilisome)
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
Sites of photosynthesis in eukaryotes
Chloroplast
The structure of chloroplast
Two membranes that has stroma space inside
It has thylokoid sacs that has chlorophylls attached to the membrane of the thylokoid
The proton force in chloroplast is generated ( place)
Across the thylokoid membrane
In the stroma: alkaline, negative
Lumen or intrathylokoid space: acidic ( pH 4), positive
Sites of photosynthesis in bacteria
Photosynthetic pigments are integrated into the internal membrane
Three possibilities of internal membrane integration in bacteria and examples
- In the cytoplasmic membrane intself: heliobacteria
- In intracytoplasmic membrane systems( when the membrane fold in on itself) :purple bacteria(vesicles,lamellae)
- In thylokoid membrane :cyanobacteria, prochlorophytes
The ancestor of the chloroplast
cyanobacteria lived in symbioses with some bacteria and eventually became chloroplast
What is chlorosome
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
What is happening in the anoxygenic photosythesis in purple bacteria
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
Do purple bacteria need an electron acceptor ?
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
Electron source to reduce NAD+ in purple sulfur bacteria and in purple nonsulfur
Purple sulfur: H2S(photoautotroph)
Purple nonsulphur:succinate ( organic compounds, photoheterotrophs, also used as carbon source)
In purple bacteria , energy of excited reaction center is not enough to reduce NAD+, so what is done for that reason and the consequence
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
How does green sulfur bacteria do photosynthesize
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
What two systems run in parallel in green sulfur bacteria?
PMF->ATP(electron cycles)
Reduce NAD+, oxidize H2S
Describe oxygenic photosynthesis
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
What is noncyclic photophosphorylation
When you need to regenerate NADPH, so the electrons are used to make NADPH and pmf
What is cyclic photophosphorylation
When you have enough reducing power (NADPH), the electrons will just come back and generate pmf instead
In cyanobacteria the part that is negative is __ and in chloroplast , this is ___
cytoplasm
stroma
In oxygenic photosynthesis water comes___ and light comes___
From the thylokoid membrane side
In the stroma
Anoxygenic photosynthesis happens in some
Cyanobacteria
What happens during anoxygenic photosythesis in cyanobacteria
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
Primary producers means
They can use inorganic compounds to make organic chemicals and use them as electrons
Examples of chemolithoautrophs
Nitrifying bacteria and sulfur bacteria
Two types of nitrogen compounds that organisms use as electron donors
Ammonia (NH3)
Nitrite (NO2)
Who oxidizes ammonia to nitrite
Nitrosomonas
Who oxidizes nitrite to nitrate
Nitrobacter
The complete oxidation of ammonia to nitrate is called
Nitrification and is performed by a concerted action of Nitrobacter and Nitrosomonas
Nitrite is ___, ___ is a better source of nitrogen in plants
Nitrite is toxic and nitrate is a better source of nitrogen for plants
Nitrification occurs only in ___
Aerobic conditions
The difference between nitrification and denitrifying-
Nitrification- bacteria uses nitrate or ammonia as electron donors
And denitrifying- using nitrogen substances as electron acceptors
In nitrosomonas spp. final electron acceptor is
O2
AMO is
ammonia mono oxygenase
AMO needs ___ electrons to oxidize ammonia and the electrons are supplied by ___
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 )
As AMO needs some energy ,so
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)
Nitrobacter spp. uses __ as a final electron acceptor
O2
Nitrobacter spp. system is similar to
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
Example of sulfur bacteria
Thiobacillus spp.
Sulfur bacteria oxidize ___
Sulfur compounds ( H2S, S,S2O3)
Thiobacillus spp. use __ as an electron acceptor
O2
Sulfur bacteria produce __ and __ , that is a dangerous chemical
SO4- and protons ( sulfuric acid)
In sulfur bacteria NADH is produced bu ____
A reverse flow of electrons
Sulfide oxidation in sulphur bacteria occurs in ___, where ___ yields S0, which is ____
Steps
The first step
Stored in cell inclusions
Methanogen do not tolerate ___
Oxygen, so strict anaerobes
Methanogen produce
CH4
Where we can find methanogens
In anaerobic sediments, landfill sites, intestinal tract of animals
Two different types of methanogens
Use of hydrogen and CO2 to produce methane , energy and water
And the others use acetate to produce methane, CO2 and energy
Methanotrophs are
Aerobes that use CH4 as a source of carbon and energy ( electron donor)
They produce CO2 and H20 and energy
Fixation of Co2 happens in
Calvin cycle
who does do fixation of CO2
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
Fixation of CO2 is
The process of getting sugars from CO2
