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BIO239 Microbiology And The Cycles Of Life > L6 Phototrophy > Flashcards

L6 Phototrophy Flashcards

1
Q

What is captured to generate enrgy in phototrophy

A

Photon (light)

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2
Q

What can capture light

A

Chlorophyll
Bacteriorhodopsins
Accessory pigments

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3
Q

What do photoautotrophs do

A

Link energy generation and cabon sioxide biomass fixation in the Calvin cycle

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4
Q

What do photoheterotrophs do

A

Harvest energy (ATP) from light and use organic carbon sources for biosynthesis

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5
Q

The excited electrons are responsible for..

A

Driving the electron transport system / proton pumping

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6
Q

What is the cycle in chlorophyll photosystems

A

Double-cycle Z pathway

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7
Q

How can light collection be maximised

A

Packing membranes with photoreceptors

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8
Q

What are 3 events that can follow after electron excitation

A

Electron transferred
Energy transferred (resonance) to another electron
Returns to ground state (energy transformed)

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9
Q

What is the most common result of an excited electron in phototrophy

A

Energy transferred (resonance) occurs commonly in photosystems

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10
Q

What wavelength of light is absorbed by bacteriorhodopsin / proteorhodopsin

A

Green wavelength

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11
Q

What groups of microbes do bacteriorhodopsin and proteorhodposin belong to

A

Bacteriorhodopsin = archaea
Proteorhodopsin = bacteria

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12
Q

What percentage of marine bacteria contain proteorhodopsin and how was this discovered

A

13%
Metagenome analysis

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13
Q

What occurs once photons have been absorbed by bacteriorhodopsins and electrons have been excited

A

Change binding in retinol and alter shape of protein
Binds H+ to one side of membrane
Releases on other side of membrane as it returns to ground state
Proton gradient used to generate ATP

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14
Q

What is photolysis

A

Light absorption coupled with splitting a molecule

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15
Q

What absorbs light in purple bacteria

A

Light harvesting centres LH1 and LH2

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16
Q

Hat absorbs light in green bacteria

A

Chlorophyll

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17
Q

What are the carotenoids in purple bacteria

A

Rhodopin and rhodopinal

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18
Q

What are the carotenoids in green bacteria

A

Carotenes e.g. Chlorobactene and isorenieratene

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19
Q

What is phycobilisome

A

Highly structured array of pigments in cyanobacteria antenna (allophycocyanin, phycocyanin and phycoerythrin)

20
Q

Where are phycobilisomes found

A

Bound to thylakoid but not embedded in the membrane

21
Q

What is the light absorbing molecule in a low vs high energy system

A

Low = bacteruichlorophyll and carotenoids
High = chlorophyll a and b and accessory pigments

22
Q

What is the wavelength of light absorbed in low vs high energy systems

A

Low = infrared, ultraviolet, green
High = red and blue

23
Q

What are the associated organisms in low vs high energy systems

A

Low = anaerobic heterotrophs such as green and purple bacteria
High = aerobic photoautotrophs e.g. Cyanobacteria

24
Q

What do green and purple bacteria hydrolyse

A

Hydrogen sulfate (H2S)

25
What is released when green and purple bacteria hydrolyse H2S
Elemental sulphur or sulphate release
26
What kind of light penetrated furthest down the water column
Infrared
27
What kind of accessory pigments do purple vacteria ocntain What wavelength of light do they absorb
Caeotenoid accessory pigments Absorb green light
28
Esplain the steps in the green / purple sulfur bacteria photosystem ehich create the membrne gradient
Absorbed photon energy is transferred to ets in membrane Electron transferred from H2S Electron is transferred via ferredoxin to make NADPH Hydrogen splits from H2S making H+ gradient across membrane
29
Explain the difference in the photosyetm of purple non-sulfur bacteria
Much lower energy is absorbed, not enough to reduce NADP to NADPH directly H+ is transferred to create gradient for ATP synthase motor Cyclic phosphorylation
30
What wavelengths of light does chlorophyll absorb
Red and blue
31
Which bacteria is the only one to use both photosystems I and II
Cyanobacteria
32
What are 3 components of cyanobacterial cells
Thylakoids Lipid and gas vesciles Carboxysome bodies
33
Which microbes carry out aerobiv photosynthesis in the Winogradsky column
Cyanobacteria and algae
34
What is the role of microbes carrying out aerobic photosynthesis in the Winogradsky column
Release oxygen to be used by aerobic heterotrophs Fix carbon into the system from carbon dioxide Cyanobacteria are also able to fix nitrogen
35
What microbes carry put anaerobic photolysis in the Winogradsky column
Green sulphir bacteria Purple sulohur bacteria Purple non-sulphir bacteria
36
What do purple non-sulphir bateria fix What is their nutritional mode
Fix carbon dioxide Use hydrogenetrophy or heterotrophy
37
What determines the limit for purple non-sulphir bateria growth
Sensitive to hydrogen sulphide
38
What is the nutritional mode of purple sulphur bacteria and how is this carried out
Largely photoheterotrophic, can respire anaerobically Split H2S to S
39
What is the nutritional mode of green sulphir bacteria How do they achieve this How do they fix carbon dioxide
Photoautotrophic Splie H2S Reverse TCA cycle to fix CO2
40
What are 3 alternative methods of arbon fixation besides the Calvin cycle
Reverse TCA cycle (green sulphur bacteria) Acetly-CoA pathway 3-Hydroxypropinate cycle
41
Where is Rubisco found
In carboxysomes
42
What converts HCO3- to carbon dioxide
Carbonic anydrase
43
What prevents diffusion of carbon dioxide in carboxysomes
Polyhedral protein shell
44
What microbes carry out the reverse TCA cycle
Green sulphur bacteria Sulphur-reducing archaea Epsilonproteobacteria in hydrothermal vents
45
What microbes use the Acetly-CoA pathway
Methanogens, soil anaerobes, autotrophic sulphur reducers
46
What microbes use the 3-Hydroxypropinate cycle
Sulphir oxidisers
47
What is a chlorosome
The antenna complex of green bacteria - mainly carotenes (chlorobactene + isorenieratene)

BIO239 Microbiology And The Cycles Of Life (12 decks)

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