Lecture 10: Autotrophy/Microbial Diversity Flashcards

(32 cards)

1
Q

Chemoautotrophs

A

Instead of using light, these microbes use
inorganic redox reactions as sources of
energy
 Also called lithoautotrophs or chemolithoautotrophs
- These organisms are able to fix CO2, but need
a source of energy

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2
Q

What do chemoautotrophs do?

A

they oxidize compounds to gain energy
- sulfur compounds (H2S, Beggiatoa)
- ammonia for nitrosomonas
- Hydrogen gas for hydrogenomonas
- Ferrous Iron for Thiobacillus ferrooxidans

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3
Q

lithotrophy

A

 Oxidation of
inorganic molecules
produces energy
 Energy is captured
in redox couples
 Flows through
electron transport
chain to terminal
electron acceptor
 Usually oxygen, sometimes sulfate
or nitrate

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4
Q

nitrifyers

A

 Nitrifying bacteria
convert reduced NH4+ to Nitrite (NO2-)
 Nitrosomonas
 Nitrosospira
 Can be further
oxidized to nitrate
(NO3)
 Nitrobacter
 Nitrococcus

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5
Q

Sulfur Oxidizers

A
  • Oxidize sulfur,
    hydrogen sulfide,
    thiosulfate
     Produce hydrogen
    sulfate
     Direct oxidation of
    sulfite
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6
Q

What is the best studied sulfur oxidizer?

A

Thiobacillus
- low pH optimum

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7
Q

What is sulfur oxidizers’ intermediate? What does it do?

A

APS
- APS intermediate can
result in substrate
level phosphorylation ATP

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8
Q

Photoautotrophy

A

 Organisms that can derive energy from
sunlight, carbon from CO2
 There are many microorganisms that fit this description

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9
Q

Oxygenic photoautotrophs

A

 Non-cyclic photophosphorylation- release O2
 Cyanobacteria, green algae

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10
Q

Anoxygenic photoautotrophs

A

 Cyclic photophosphorylation, no oxygen gas
 Use sulfur as electron donor
 Green and purple bacteria

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11
Q

Photosynthesis

A

 Photosynthesis is used by many organisms to generate energy and
carbon
 Plants
 Many types of bacteria

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12
Q

Phases of photosynthesis

A
  • Light reactions photophosphorylation
     Dark reactions Calvin-Benson cycle
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13
Q

Photosynthesis Light reactions

A

 Photophosphoryl
ation
 Cyclic reaction
uses no other inputs besides light energy
 Non-cyclic
photophosphoryl
ation generates oxygen gas, uses water

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14
Q

Photoreactive dyes

A

 Bacteria use a number of different ones
 Different bacterial
species used different
chlorophylls
 Also, bacteriorhodopsin
used by halophilic Archaea

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15
Q

Rhodopsin

A

absorb a photon, change the shape of the retinal in the center of the photoreceptor,

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16
Q

Calvin Benson Cycle

A

 Light-independent or
dark reactions
 End result is the
production of
glucose for use in
cell metabolism
 This is carbon
“fixation”
 Cost of CB cycle is
18 ATP and 12
NADPH
 This process or the
reverse TCA cycle
can occur in bacteria

17
Q

Photoheterotrophy

A

 Organisms that use light for energy source, but are unable to fix CO2
 Bacteria of this type must use organic carbon as a source of cell material
 Purple non-sulfur bacteria
-> Rhodopseudomonas
 Green non-sulfur bacteria
-> Chloroflexus

18
Q

Evolutionary History

A

 4.6 bya – earth
cools
 3.5-3.8 bya – first
unicellular life forms
(stromatolites)
 Clear microbe
fossils ~ 2 bya
 First eukaryote ~
1.4 bya

19
Q

First eukaryotic cell

A

Archaea and
Bacteria lived for
~2 by before first
eukaryote
 Most popular
theory –
Endosymbiont
(Margulis)
 Nucleus
 Mitochondria
 Chloroplast

20
Q

three domains of life

A
  • bacteria
  • archaea
  • Eukarya
21
Q

All living things are classified using
the ______ system, developed by
the Swedish botanist ____________

A
  • Linnaean
  • Carolus Linnaeus
22
Q

Candidate Phyla Radiation

A
  • discovered after people stopped throwing away all 0.2 micron groups that were filtered out and began actually studying them.
23
Q

Archaea

A
  • physiologically similar to bacteria
  • evolutionarily ancient divergence
  • crenarchaeota
  • euryarchaeota
  • extremophiles
  • methanogens
24
Q

Archaeal Cell Envelope

A

ether-linked lipids
- G+ or - structure

25
pseudo-murein
similar to peptidoglycan - N-acetyltalosaminuronic acid - B-1,3-glycosidic bond - different peptide junctions
26
Archaeal Metabolism
- dont use emden-meyerhoff glucose oxidation - Methanogens don’t catabolize glucose  Halophiles use modified Entner- Douderoff  Autotrophy is widespread  Fix CO2, use reductive TCA cycle rather than Calvin Benson
27
methanogens
 Strict anaerobes  Within phylum Euryarchaeota  Can start from CO2 and H2, or intermediates  5 orders  27 genera  Lots of variation
28
thermoplasma
 Thermoacidophiles  Lack cell wall  3 genera/families
29
Extreme thermophiles
 Pyrococcus  Paleococcus  Thermococcus  Reduce Sulfur to Sulfide
30
Extreme Halophiles
 Class Halobacteria  Includes 15 genera  Require at least 1.5 M NaCl to grow  Halobacterium salinarium (H. halobium)  Photosynthetic  No chlorophyll  Purple membrane  Bacteriorhodopsin
31
Uncultured Bacteria
 Many clades have few/no cultured representatives  Some of the most common organisms on earth are rarely if ever cultivated
32
Candidate Phyla Radiation
bacteria pass thru 0.2 micron filters