Biogeochemical Cycles

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Biogeochemical Cycles

• Where do macromolecules come from
• Where do they go?

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Elements transferred between compartments (pools)

• Active accessible to living things
• Storage inaccessible

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Biogeochemical Cycle Overview
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What is a Biogeochemical Cycle?

• Reuse of materials in ecosystem by living
  organisms
• Biological components (biotic)
• Producers
• Consumers
• Detritivores (scavengers decomposers)
• Geological components (abiotic)
• Atmosphere (gases water vapor)
• Solid crust of the earth (minerals chemicals)
• Earths water (oceans, lakes rivers)

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Biogeochemical Cycles

• Water needed to make CARBOHYDRATES, LIPIDS,
  PROTEINS

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THE WATER CYCLE
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Other Biogeochemical Cycles

• Water cycle
• Carbon needed to make CARBOHYDRATES, LIPIDS,
  PROTEINS, NUCLEIC ACIDS

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CARBON CYCLE
atmosphere
photosynthesis
respiration
biosphere
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CARBON CYCLE
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CARBON CYCLE
atmosphere
photosynthesis
combustion
respiration
biosphere
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Other Biogeochemical Cycles

• Water cycle
• Carbon cycle
• Nitrogen needed to make PROTEIN NUCLEIC ACIDS

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Nitrogen Cycle
atmosphere
loss
fixation
gain
denitrification
biosphere
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Nitrogen Cycle

• Despite abundance in the atmosphere (77 of
  Earths atmosphere made of N2 gas) nitrogen is
  actually a limiting factor to plant growth
• Most organisms cannot use elemental N2 and must
  use nitrogen present in soil minerals
• N2 gas is fixed into these nitrogen compounds
  mainly by bacterial processes

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Stages of Nitrogen Cycle

• Ammonification
• Most soil nitrogen is result of decomposition of
  nitrogenous compounds by bacteria (amino acids,
  proteins, etc.)
• These bacteria release excess nitrogen in the
  form of ammonia (NH3) or ammonium ions (NH4)

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Stages of Nitrogen Cycle

• Ammonification
• Nitrification (by nitrogen-fixing bacteria)
• Several species of bacteria able to oxidize
  ammonia to get energy for metabolism
• Although nitrite (NO2-) is toxic, it is quickly
  changed to nitrate (NO3-) by another group of
  bacteria
• Most plants take up nitrogen in the form of
  nitrate

2NH3 3O2 ? 2NO2- 2H 2H2O
2NO2- O2 ? 2NO3-
NITRATE
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Stages of Nitrogen Cycle

• Ammonification
• Nitrification
• Assimilation
• Requires energy expenditure to attach ammonium
  ions to carbon-containing compounds
• Amino acids produced
• Amino acids form PROTEINS

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Loss of Soil Nitrogen

• Nitrates steadily lost from cycle by
• Harvesting plants
• Soil erosion
• Fire
• Leaching
• Denitrifying bacteria these break down nitrate
  into N2 gas (in the absence of oxygen) usually
  takes place in poorly drained soil

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NITROGEN CYCLE ANIMATION
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Other Biogeochemical Cycles

• Water cycle
• Carbon cycle
• Nitrogen cycle
• Phosphorus needed to make DNA RNA (nucleic
  acids) as well as ATP (the energy currency of
  cells)

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PHOSPHORUS CYCLE
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Other Biogeochemical Cycles

• Water cycle
• Carbon cycle
• Phosphorus
• Sulfur needed to make certain proteins

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SULFUR CYCLE
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QuestionsWhat would happen if a biogeochemical
cycle slowed down or sped up?What might
cause such a thing to happen?

• Turn to your neighbor and explain. Then write a
  summary of what you both concluded.