Element Hunting: Carbon

Element Hunting: Carbon
On our last element hunt we encountered the macronutrient Nitrogen. To re-cap, there are 18 elements required for plants to live.

They consist of 9 macronutrients& 8micronutrients:

C, H, O, N, P, K, Ca, Mg, S, B, Cl, Cu, Fe, Mn, Zn, Mo, & Ni  (&& many argue Si should be added to the list)

This week’s macronutrient, Carbon, will help guide us through the light-independent reactions of photosynthesis.

  • The elements H, O, and C account for 96% of a plant’s mass
  • Water (H₂O) and carbon dioxide (CO₂) are the source for a plants H, O, and C
  • CO₂ supplies the C and O essential for photosynthesis

There are two stages in photosynthesis; the first—light dependent reactions—use light energy to synthesize ATP and NADPH (the molecules notoriously known for creating energy and storing it).

NADPH then provides the energy required to drive the subsequent reactions during the second stage of photosynthesis, the light independent reactions—collectively known as The Calvin Cycle.


The Calvin Cycle (click to enlarge)


And if scientific names weren’t confusing enough, the light [in]dependent reactions only takes place during the “daytime” –which is why you run your CO₂ burners during the “day.”

Side-note: Remember when I first talked about CO₂ being one of the two raw materials REQUIRED for photosynthesis to occur and what happens when too much CO₂ is present & how it affects photosynthesis? Here’s a  link to my previous post where you can touch base with RuBisCO activase again.

Briefly, the general equation for photosynthesis is:

2n CO2 + 2n H2O + photons2(CH2O)n + 2n O2  

carbon dioxide + water + light energy → carbohydrate + oxygen

And the overall equation for the light independent reactions is:

3 CO2 + 9 ATP + 6 NADPH + 6 H+ → C3H6O3-phosphate + 9 ADP + 8 Pi + 6 NADP+ + 3 H2O

The Calvin Cycle à produces a 3 Carbon sugar, Glyceraldehyde 3-phosphate, aka G3P. Once the enzyme RuBisCO (not illustrated in equation since enzymes only facilitate and are NOT consumed in the process) captures atmospheric CO₂ and cycles the Carbon in series of chain reactions using NADPH and ATP as working fuel.

What if the cycle doesn’t use all the Carbon available? Excess G3P (3 Carbons) can then be used to form bigger sugar molecules such as glucose (6 Carbons), sucrose (12 Carbons), starch, and cellulose (even MORE Carbons with about 1500 glucose units).

So how does the production of G3P from (3) CO₂ molecules come into play with your medical marijuana plants? Or on a personal scale, how does this directly affect you?

The metabolism of Carbon during photosynthesis produces essential building blocks for plants, animals, and humans, as they can further be synthesized to produce amino acids and lipids. These sugars make up the cell walls of living organisms, form supporting structures in plants, when broken down to a simple glucose molecule can circulate in the blood stream as energy, and serve as a source of fiber in human diets. Not to mention energy, energy, ENERGY!

Lovely new ladies getting ready to take off. They can't do it without Carbon!

Lovely new ladies getting ready to take off. They can’t do it without Carbon!


In my book, Carbon is synonymous with life.

Hope this has helped. As always,  happy growing!

2 Responses to “Element Hunting: Carbon”

  1. Indoh November 11, 2014 at 4:00 am Permalink

    Hi guys..quick question, does my room has to be sealed in order to run CO2? I have a ducted lights set up with a 8″ filter. Thank you

    • Shelby November 14, 2014 at 12:04 pm Permalink

      It doesn’t necessarily need to be sealed, but to avoid all the CO2 from getting exhausted out you can turn off the fans for a few minutes to let your plants capture the CO2. Don’t forget to only run CO2 when the lights are on 🙂

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