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Geomicrobiology > Metabolisms > Flashcards

Metabolisms Flashcards

1
Q

What is metabolism

A

all biochemical processes within a cell

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2
Q

what are the two main types parts of metabolism and describe them

A

1 - Anabolism: formation of biomass (growing)
2 - Catabolism: formation of energy from substrate (getting smaller but producing energy)

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3
Q

Describe Anabolism and give an example

A

use of chemical energy to convert nutrients and simple compounds into complex molecules

example: photosynthese

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4
Q

what are the two main types of Catabolism
and
describe it

A

fermentation and respirations are the two mains types

oxidation of organic or inorganic compounds, accompanied by the release of energy (ATP) and waste

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5
Q

What is ATP

A

Adenosine triphosphate is a nucletide

it carries energy in a form that cells can use

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6
Q

Which process produces ATP and which process uses it

A

Anabolism uses ATP and Catabolism produces it

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7
Q

What is a PED

A

primary electron donor

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8
Q

What is a TEA

A

terminal electron acceptor

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9
Q

what causes more energy to be conserved (less lost as heat) in the ETC (electron transport chain)

A

-when there is a greater difference in the electrode potential between the PED and the TEA
-there are more steps in the chain
-the more steps there are the more energy is conserved

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10
Q

What is an enzyme

A

a biological catalyst
(without which most biological reactions would occur too slowly for life)

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11
Q

Why might fermentation occur instead of respiration?

A

no need for external TEA, so redox reactions can occur internally regardless of exturnal environments

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12
Q

why might respiration occur instead of fermentation?

A
  • more efficient: more ATP produced
  • the electrode potential is bigger between the products meaning a bigger chain and less energy loss
  • fermentation end products are still relatively complex molecules containing usable energy
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13
Q

What are the TEAs for aerobic and anaerobic respiration

A

aerobic TEA - Oxygen

anaerobic TEA - Sulfate, ferric iron (3+), arsenate, nitrate (any oxidised species that can accept electrons

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14
Q

what is a facultative anaerobe

A

respire aerobically but can use other TEA when no oxygen is available

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15
Q

which type of respiration is more favourable aerobic or anaerobic

A

aerobic

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16
Q

What does photo or chemo refer to

A

energy source
photo: sunlight
chemo: preformed molecules

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16
Q

What is an obligate anaerobe

A

can only survive in an environment that is oxygen depleted

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17
Q

what does hetero or litho refer to

A

electron donor
hetero: organic compounds
litho: inorganic compounds

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18
Q

what does hetero or auto refer to

A

carbon source
hetero: organic compound
auto: inorganic compound

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19
Q

what are two examples of chemoheterotrophy and
what produces more ATP

A

Fermentation and Respiration
Respiration produces more ATP

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19
Q

What is the process of chemoheterotrophy

A

uses chemical energy sources and organic carbon

19
Q

what is the generalised equation for AEROBIC chemoheterotrophic respiration

A

C6H12O6 + 602 = 6CO2 + 6H2O
- organic C is oxidised by O2
- oxygen is reduced by organic C
- produces more ATP than other respiration pathways

20
Q

Types of ANAEROBIC chemoheterotrophy

A

Reductions of other TEAs

including:
- Dissimilatory nitrate reduction
- Dissimilatory manganese reduction
- Dissimilatory iron reduction
- Dissimilatory reduction of other metals or
metalloids
- Dissimilatory sulfate reduction
- Methanogenesis

20
Q

Dissimilatory nitrate reduction: who does it and where is it important

A
  • bacteria only
  • important role in soils and freshwaters subject to agricultural pollution or sewage
20
Q

Dissimilatory iron reduction

A
  • Fe-oxides ubiquitous in soils and sediments
  • Implicated in release of Fe 2+ in anoxic
    groundwaters, degration of org matter in
    deeply buried sediments + formation of
    variegated red beds in sedimentary rocks
  • some used in BIOREMEDIATION to degrage contaminants
  • e- shuttling used
21
Q

Dissimilatory manganese reduction

A
  • some Mn-reducers are facultative anaerobes
  • some prefer Fe(III) - reduction but will reduce
    Mn if its available
  • mineral oxides cannot cross cell membrane so
    cells either attach to mineral surface or use e-
    shuttling molecules
22
Q

What are electron shuttles

A

organic compounds that speed up dissimilatory metal reduction reactions

23
Q

dissimilatory reduction of other metals and metalloids

A
  • major interest to bioremediation
  • lots of radioactive and toxic contaminants (As, Se, Cr, U, Tc, Pu)
  • Some bacteria can reduce U as a byproduce of other activites (not for energy) but Geobacter and Shewanella (Fe reducers) can derive energy from it ALTHOUGH it is not as energetically favourable as Fe reduction
24
Q

Dissimilatory sulfate reduction

A
  • wide variety of bacteria can do this (usually obliagte anaerobes)
  • found in water logged soils, brackish waters, sewage, mine waste, hot springs, oil and gas wells, deep sea hydrothermal vents and deep marine sediments (ANYWHERE ANOXIC WITH ENOUGH ORGANIC MATTER AND SULPHATE)
25
Q

Methanogenesis

A
  • methanogens
  • Strict anaerobic Archaea
  • there is chemoHETEROtrophic methanogeneis and chemolithoAUTOtrophic methanogensis
  • occupy niches in anoxic, SO4 deficient environments: swamps, water-logged soils, tundra, marine sediments, hydrothermal vents, landfill and sewage
  • PRODUCES VERY LITTLE ENERGY
26
Q

what is chemolithoautotrophy
and
how is it different to chemoautotrophy

A
  • rock eaters
  • chemo = chemical energy souce
  • litho = inorganic chemicals
  • auto = CO2

different because it oxidises inorganic compounds not organics

27
Q

Differences between chemoheterotrophy and chemolithoautotrophy

A
  • litho uses inorganic sources of Carbon
  • litho is less energetically favourable (the delta E is greater for hetero)
  • electron donors required for both ATP generation and CO2 fixation
28
Q

What do chemolithoautotrophs use as PED to produce biomass

A

inorganic species:
- H2 <—- most wide spread
-CH4 <—- methanotrophs
-H2S
-S0
-S2O3
-Fe (II)
-Mn (II)
-NH4
-NO2

and inorganic carbon
-CO2
-HCO3

29
Q

What is the TEA for chemolithoautotrophy

A

usually oxygen but not always

30
Q

Difference between methanogens and Methanotrophs

A

Methanogens - form methane

Methanotrophs - consume (oxidise) methane
-widespread wherever there is a stable source of CH4 eg:
polar regions
continental margins

31
Q

where are the two types of sulfur oxidisers found

A

Gradient organisms:
sulfur springs, microbial mats, low O2 seawater, sewage polluted freshwaters

Acidophilic organims:
acid rich environments - AMD

32
Q

Where do the two types of iron oxidisers exist

A

Neutrophiles:
-microaerophilic environments (require O2 but not too much)

Acidophiles:
- mine waste, very hot acid springs e.g. volcanic areas

33
Q

What are the most common PED and TEA for nitrogen oxidisers
and
where are they found

A

PED = NH4
TEA = O2

found in marine sediments, below chemocline of water column in anoxic basins

34
Q

What are the two major types of photosynthesis and
who does them

A
  1. Oxygenic photosythesis:
    plants, algae, cyanobacteria
  2. Anoxygenic photosythesis:
    green and purple bacteria, heliobacteria
34
Q

What are phototrophs

A

light eaters!
they use sunlight as their energy source

examples:
plants
algae
some bacteria

35
Q

What is the main pigment used in photosynthesis to transform light energy into chemical energy

A

Chloropyhll

36
Q

What are the two categories of chlorophyll (chl)

A
  • light harvesting chl
  • reaction-centre chl: transforms light energy (photons) into chemical energy (PEDs)
37
Q

What are the light and dark parts of photosynthes

A

light - initial stage where light energy is absorbed and transformed into ATP

dark - dont require light, include: CO2 (autotrophy) and N2 fixation

38
Q

Oxygenic phototrophs

A
  1. Algae (eukaryotic)
  2. Cyanobacteria (prokaryotic)
39
Q
  1. green sulfur bacteria
A

strictly anaerobic

39
Q

Anoxygenic phototrophs

A
  1. green sulfur bacteria
  2. green nonsulfur bacteria
  3. purple bacteria
  4. purple nonsulfur bacteria
  5. Heliobacteria
40
Q
  1. green nonsulfur bacteria
A

aerobic or anaerobic

41
Q
  1. purple bacteria
A

can live in deeper waters where IR radiation is flitered out

42
Q
  1. purple nonsulfur bacteria
A

similar to purple sulfur bacteria but cant handle too much H2S

43
Q
  1. heliobacteria
A

obligate anaerobic photoheterotrophs
common in rice paddies

Geomicrobiology (12 decks)

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