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Lecture # 3: OM production, Biochemical Classes, and Elemental Considerations-I

Lecture # 3: OM production, Biochemical Classes, and Elemental Considerations-I. Basic Photosynthesis: 2 linked components. Part-I: Photosystems= power & O 2. Light is used to strip H’s & electrons off H20- create “power” ( ultimately in form of cell “energy” molecules ATP, NADPH)

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Lecture # 3: OM production, Biochemical Classes, and Elemental Considerations-I

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  1. Lecture # 3: OM production, Biochemical Classes, and Elemental Considerations-I

  2. Basic Photosynthesis: 2 linked components

  3. Part-I: Photosystems= power & O2 Light is used to strip H’s & electrons off H20-create “power” ( ultimately in form of cell “energy” molecules ATP, NADPH) Liberated O2. (implications for H-powered economy?)

  4. Part-II: Calvin or Krebs cycle Energy used to fix CO2 – reduce it with added H’s to “simple sugar”

  5. Rubisco- enzyme that fixes carbon(most abundant enzyme on earth)

  6. Rubisco- Carboxylation RX

  7. “C3 plant” = C-fixation product is 3C-sugar (“3PG”= 3 phosphoglycerate) C3 = “standard” plant, ~ only thing in ocean

  8. Important exceptions on land- “C4” & “CAM” plants: dry climates- where loss of water is critical- plants have evolved a different architecture to “pump” CO2 in, and save water!

  9. “C4-plants” Typically grasses (space segregation) “CAM”-plants, Cacti, etc. (temporal segregation-fix C at night only..)

  10. Basic Organic Matter Produced = SUGAR 2 Lots of Ugly Biochemistry.. C3H4O3 + Phosphate C6H12O6 Recall “CHO” = shorthand for OM Note: only C, H, O !

  11. Not a coincidence:Glucose: most abundant biomolecule on planet Earth “Elemental Ratio” = relative atom building blocks in molecule * Usually all else is “normalized” to Carbon Glucose C : O = 1 C : H = 2 & that’s it! C6H12O6 These kind of “ratios” can be highly diagnostic- not for a specific molecule- but for a KIND (or “class”) of molecule

  12. Organic Analysis: Part I: Introduction to concept of “Bulk” vs. “Molecular-Level”

  13. Why would such super basic info be useful? In part: Organic Geo-Chemistry vs Organic Lab-Chemistry Difference in approaches: Main factors which separate the two worlds: Mixtures (Geo) vs pure compounds (Lab) Complex (and unknown) Matrixes vs Simple, Controlled (and known) Matrixes. Large abundance (and sometimes a focus on!) Unknown compounds/ homologues vs ~ attempt to work with 100% Known compounds

  14. Types of Tools: “Bulk” vs “Molecular-Level” Bulk analyses: e.g. CHN (elemental) & stable isotopes (and also some spectroscopy like NMR, FTIR,): 1. Advantages:“all inclusive” (representative) and often relatively easy (combustion or spectroscopic) 2. Disadvantages: insensitive to minor diagnostic components, low information potential (most is lost); major mistakes in technique can be “invisible”. 3. Mixtures: can be problem.

  15. Elemental Ratios : Why measure them? * Fixes/ predicts Stoichiometryof larger biogeochemical cycles- * Proxy for composition:tells about possible composition * State of OM : Tells you about state of OM degradation / alteration

  16. Back to our Glucose Elemental Ratios:Would other biochemicals be the same, or very different? How? Glucose C : O = 1 C : H = 2 & that’s it! C6H12O6

  17. Or put another way: Where does the the “rest” of organic matter come from? What’s it like? C6H12O6

  18. Amino Acids Carbohydrates Nucleic Acids Lipids Central (synthetic) metabolism &“Major biochemical classes”

  19. Elemental Ratios and Production of OM. WHATS MISSING? Recall: Basic equation of OM production (photosynthesis): H20 + C20  CH20 + O2 * However, main thing missing from this equation is ( of course) the key “heteroatoms”- IE: “nutrient” elements.

  20. Nutrients! The Redfield-Ketchum-Richards (RKR) Equation ): 106 CO2 + 16 HNO3 + 1PO4 + 122 H2O (CH2O)106(NH3)16PO4 + 138 O2  Common Redfield Ratio: C:N:P = 106:16:1

  21. Aside: Importance of these ratios in nature  They “FIX” Organic production / degradation within larger inorganic biogeochemical cycles • Predicts inorganic nutrients needed to produce OM- therefore fixes demand side of inorganic N, P, S ( C ) etc. • Predicts Oxygen and Carbon balances on respiration: Tells how much atm. Free O2 is needed vs CO2 liberted. • Clues to Biological “fate” = cycling speed : Tells you 1) ~ energy content of OM and 2) Nutrient content

  22. Note: in practice, commonly only measure four elements : C, N, O, H Why?

  23. Analytical : where measured ratios come from Real Mixture of total biochemicals  [ black box bulk roasting]  Ratios of gasses produced C/N = x H/C = y O/C= x Can also add “P” –but totally separate and complex analysis

  24. Note: again, most commonly interpreted as a ratios with C (organic carbon only = “OC”) C/N = x, H/C = y, O/C= x These are “atomic ratios”: * they tell you directly about the OM in a given sample * they also relate directly to larger cycle stoichiometry However, Careful! Primary data is often reported instead as wt % C, N, etc. • Ie: normalized to mass of sample sent in- *This tells you about total organic content * BUT has much less “direct” meaning for composition & organic cycling

  25. Ocean POM Ocean Seds (C/N)a 10 20 30 40 0 Ocean DOM Bacteria Humics Plankton Ways to examine / interpret Atomic ratios 1) Single dimension: or place on a continuum of “end-members”

  26. Ways to examine / interpret Atomic ratios 2) Multi-dimension: or “Property-Property Plots” Depending on what you plot on it, it can tell you lots of things Eg: • nutrients vs energy = “degradability” in fresh stuff • H vs O content ~ degree of geo-molecule formation

  27. 2.0 1.0  Degree of degredation Nutrient Potential 0 0.15 0.3 Eg: Biological / Ecological Potential Energy Potential (reduction) H/C N/C Will come back to this..soon.

  28. NEXT:PART II: More focus on Basic Biochemical Classes

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