Nitrogen importance of plants, nitrogen fixation process and biological nitrogen fixation.

1. NON SYMBIOTIC NITROGEN
FIXERS.
PRESENTED BY:
TAYYABA ARIF.

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3. WHY NITROGEN IS
NECESSARY FOR THE
PLANTS:
 Major substance.
 Building blocks.
 Constituent element of the:
 Chlorophyll.
 Cytochromes.
 Alkaloids.
 Role in the metabolism,
reproduction, and the growth etc.
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4. NITROGEN FIXATION:
 The conversion of free nitrogen into the nitrogen salts
to make it available for the absorption of the plants.
 The major conversion of N2 into ammonia, and then
into proteins, is achieved by microorganisms in the
process called nitrogen fixation.
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5. Role of organisms in
nitrogen fixation:
 Organisms have a central role in almost all
aspects of nitrogen:
 Some bacteria can convert N2 into ammonia by
the process termed nitrogen fixation.
 Other bacteria bring about transformations:
Ammonia to nitrate, and of nitrate to N2 or other
nitrogen gases.
 Many bacteria and fungi degrade organic matter,
releasing fixed nitrogen for reuse by other
organisms.
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7. BIOLOICAL FIXATION:
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 Fixation of the nitrogen into the nitrogen salts
with the help of the organisms.
 TYPES OF THE BIOLOGICAL FIXATION:
 Symbiotic fixation.
 Non-symbiotic fixation.

8. NON-SYMBIOTIC NITROGEN
FIXATION:
 Fixation carried by the free living
microorganism eg: aerobic, anaerobic and
blue green algae etc.
SYMBIOTIC NITROGEN
FIXATION:
 Fixation of the free nitrogen in the soil by
microorganism eg: nodule formation.
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9. BIOLOGICAL N2
FXATION:
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 The biological nitrogen fixation is carried out by:
 some bacteria, cyanobacteria and symbiotic bacteria
 Biological nitrogen fixation occurs in the presence of the
enzyme nitrogenase which is found inside the nitrogen fixing
prokaryote.
 In addition to this enzyme, a source of reducing equivalents
(ferredoxin (Fd) or flavodoxin in vivo), ATP and protons are
required.

10. BIOLOGICAL N2
FXATION:
 The process involves a number of complex
biochemical reactions:
 N2 + 8H2+ 16ATP ------> 2 NH3 + 2H2+ 16ADP +
16 Pi
 The equation above indicates that one molecule
of nitrogen gas (N2) combines with eight hydrogen
ions (also known as protons) (8H+).
 Form two molecules of ammonia (2NH3) and two
molecules of hydrogen gas (2H2).
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11. BIOLOGICAL N2
FXATION:
 This reaction is conducted by an enzyme
known as nitrogenase.
 The 16 molecules of ATP (ATP = Adenosine
Triphosphate, an energy storing compound)
represent the energy required for the BNF
reaction to take place.
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12. BIOLOGICAL N2
FXATION:
 In biochemical terms 16 ATP represents a
relatively large amount of plant energy.
 Thus, the process of BNF is 'expensive' to
the plant in terms of energy usage.
 As ammonia (NH3) is formed it is converted to
an amino acid such as glutamine. The
Nitrogen in amino acids can be used by the
plant to synthesize proteins for its growth and
development.
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