8.2. Bacterial Diversity in The Nitrogen Cycle
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Microorganisms can use nitrogen in 3 forms:
• ammonia/ ammonium (NH3/ NH4+) • Nitrate/ Nitrite (NO3-/NO2-) • dinitrogen (N2)
T/F All life forms must assimilate nitrogen, and nitrogen must be transformed to be assimilated into the organism
true
T/F Archaea are the only life forms that can conserve energy from transformations of inorganic nitrogen species
False Archaea AND BACTERIA are the only ones
What are the 3 broad groups of bacteria/ archaea that control the nitrogen cycle?
• Diazotrophs • Nitrifiers • Denitrifiers
Diazotrophs (aka _____-fixing bacteria) fix ___ to make ___
Nitrogen (N2) N2 –> NH3
____ is the only biologically available form of nitrogen
NH3 (incorporated into amino acids)
T/F N2 fixation is relatively energy inexpensive
False very energy EXPENSIVE - it’s a huge investment to make N2 into biologically available NH3
Nitrogenase=
the enzyme that completes nitrogen fixation (O2 sensitive)
Many diazotrophs evolved the ability to protect nitrogenase from ___
oxygen
T/F LUCA was an N2 fixator
We don’t know Originally thought this was true, now we’re not sure