MC7: Microbial geochemical cycling Flashcards Preview

BS1040: Microbiology and Cell Biology > MC7: Microbial geochemical cycling > Flashcards

Flashcards in MC7: Microbial geochemical cycling Deck (20)
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1

What are biogeochemical cycles?

A pathway by which a chemical substance moves through biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth

2

Give examples of biotic and abiotic factors

Biotic: predators, decomposers

Abiotic: air, water, minerals

3

Define 'reservoir', including the terms 'source' and 'sink'.

A part of the biosphere that contains significant amounts of an element. It acts as both a source for that element for living organisms and as a sink to which it returns.

4

List the major processes that occur in the microbial-driven carboin cycle

  • Oxygenic photosynthesis
  • Aerobic respiration
  • Anaerobic respiratioin
  • Fermentation
  • Anoxygenic photosynthesis
  • Acetogenesis
  • Methanogenesis
  • Methanotrophy

5

Describe the aerobic carbon cycle

  1. Photosynthesis fixes CO2 into biomass
    • This produces O2 and organic compounds
  2. Lithotrophs also reduce CO2 to biomass
  3. Respiration returns CO2 to the atmosphere
    • There is a net gain of O2/loss of CO2​ in photic zone

6

Describe the anaerobic carbon cycle

  • Has lower cyclling rate than aerobic cycles
    • Less iron and less redox potential than O2
  • Occurs in the subsurface of the environment
    • e.g. soil, benthos, rock
  • Involves fermentation and lithotrophic (chemoautotrophic) respiration
    • Incomplete breakdown of biomass carbon
    • Formation of peat, oil, gas

7

Give an example of a microbe that undergoes oxygenic photosynthesis

Cyanobacteria

(Martha's fave – don't forget it!)

8

Give an example of a microbe that undergoes chemoautotrophy

Thiobacillus

Leptospirillum

9

Give an example of a microbe that undergoes methanotrophy

Methylococcus

Methylosinus

10

Give an example of a microbe that undergoes acetogenesis

Clostridium acetobutylicum

11

Give an example of a microbe that undergoes anoxygenic photosynthesis

Heliobacteria

12

Give an example of a microbe that undergoes anaerobic respiration

Yeast

13

Give an example of a microbe that undergoes fermentation

Yeast

14

List the major processes in the nitrogen cycle

  • Nitrification
  • Nitrogen fixation
  • Denitrification
  • Assimilation
  • Ammonification
  • Anaerobic ammonium oxidation (anammox)

15

Give an example of a microbe that undergoes nitrogen fixation

  • Klebsiella (in soil)
  • Clostridium (in soil)
  • Pseudomonas (in soil)
  • Rhizobium (within legumes – symbiotic relationship)
  • Cyanobacteria (in oceans and freshwater)

16

Give an example of a microbe that undergoes nitrification

Nitrosomonas (oxidises NH4+ to NO2)

Nitrobacter (oxidises NO2 to NO3)

17

Give an example of a microbe that undergoes denitrification

Pseudomonas species

18

Give an example of a microbe that undergoes ammonification

Planctomycete genera

Kuenenia stuttgartiensis

19

Give a brief overview of the carbon cycle

20

Give a brief overview of the nitrogen cycle