Chapter 22-1

  1. The purpose of the nitrogen cycle:
    Animals need nitrogen to make amino acids, proteins and DNA. However, the nitrogen in the atmosphere is not in a form that they can use. So animals get the nitrogen they need by eating plants or other animals that contain nitrogen.
  2. The form(s) of nitrogen a cell can use:
  3. Fixation:
    Nitrate (NO3-) –(denitrification)à N2 –( nitrogen fixation)à Ammonia (NH4-)
  4. Nitrification (Specific):
    Ammonia (NH4-) –(nitrification by soil bacteria)à NO2- (nitrite) –(nitrification by soil bacteria)à nitrate (NO3-).
  5. Nitrification (General):
    the oxidation of ammonia to nitrite (NO2-) and nitrate (NO3-).
  6. What molecule assists in providing the anaerobic environment required for nitrogen fixation?
    The molecule that assists in providing the anaerobic environment required for nitrogen fixation is leghemoglobin
  7. Leghemoglobin:
    acts like and oxygen sponge and dumps oxygen out to make no-oxygen environment for nitrogen. It has a high-affinity oxygen-binding heme group and keeps fixation environment anaerobic
  8. How many electrons are required to fix the two
    Nitrogen atoms in N2, and what are the specific molecules providing them?
    It takes 8 electrons to fix one N2. Nitrogen gets “fixed by reduction, which happens by a reduced dinitrogenase donating its electrons to N2.

    • The molecules providing the electrons are 4CoA +
    • 4 pyruvate.
  9. Dinitrogenase complex enzymes:
    dinitogenase reductase and dinitrogenase
  10. many ATP are required for a one electron
    transfer through the Dinitrogenase complex?
    ATP required for a one electron transfer though the dinitrogenase complex is 2 (2ATP per electron).
  11. General similarities between the anabolic amino acid pathways:
    transamination and glutamate is the transport form of nitrogen.
Card Set
Chapter 22-1