Photosynthesis is very easy to understand, once you get the hang of it. Everyone understands chemical equations, right?
To start, the most common and prevalent form of photosynthesis is oxygenic, and has the following form when expressed as a chemical equation:
6CO2 + 6H2O = C6H12O6 + 6O2
In case you forgot what you leaned in high school science class, what that equation means is that six molecules of CO2 (carbon dioxide) combines with six molecules of H2O (water) through energy (light). This reaction produces one molecule of C6H12O6 (glucose) and six molecules of O2 (oxygen).
To start, the most common and prevalent form of photosynthesis is oxygenic, and has the following form when expressed as a chemical equation:
6CO2 + 6H2O = C6H12O6 + 6O2
In case you forgot what you leaned in high school science class, what that equation means is that six molecules of CO2 (carbon dioxide) combines with six molecules of H2O (water) through energy (light). This reaction produces one molecule of C6H12O6 (glucose) and six molecules of O2 (oxygen).
WARNING: UNCHARTED TERRITORY, DO NOT ENTER UNLESS PREPARED FOR THOROUGH MIND-BLOWING!!
It is the conversion between CO2 (which is produced in respiration) and water that produces glucose, one of the body's main sources of energy. In a plant this usually occurs in the leaves, which have an abundance of chloroplasts. These chloroplasts are the organelles which conduct photosynthesis within a cell. They are similar to cyanobacteria and it is thought that chloroplasts may have arisen from some sort of endosymbiosis with early eukaryotes. Regardless, modern plants have evolved to make use of these chloroplasts to produce glycogen through the Calvin cycle. This happens after capturing the necessary energy by making use of chlorophyll to complete light dependent reactions on
thylakoid membranes within the chloroplasts. These reactions make use of four main protein complexes, namely Photosystem II, Cytochrome b6f complex, Photosystem II and ATP syntheses to achieve the net reaction.
2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2NADPH + 3ATP (Pi = inorganic phosphate)
These components are then used to fuel stage two of the Calvin cycle to complete light independent reactions, which convert these components into glyceraldehyde 3-phosphate .This can then be used to form most carbohydrates such as glucose. As it is a cycle, most of the G3P made using this reaction will be used to regenerate the original materials which are used to convert additional CO2 and H2O into G3P.
3 CO2 + 6 NADPH + 5 H2O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi
Okay, I suppose that is a little complicated, after all .
This following schematic demonstrates the sum of all needed parts and products in order to produce one molecule of G3P as indicated by the equation above.
It is the conversion between CO2 (which is produced in respiration) and water that produces glucose, one of the body's main sources of energy. In a plant this usually occurs in the leaves, which have an abundance of chloroplasts. These chloroplasts are the organelles which conduct photosynthesis within a cell. They are similar to cyanobacteria and it is thought that chloroplasts may have arisen from some sort of endosymbiosis with early eukaryotes. Regardless, modern plants have evolved to make use of these chloroplasts to produce glycogen through the Calvin cycle. This happens after capturing the necessary energy by making use of chlorophyll to complete light dependent reactions on
thylakoid membranes within the chloroplasts. These reactions make use of four main protein complexes, namely Photosystem II, Cytochrome b6f complex, Photosystem II and ATP syntheses to achieve the net reaction.
2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2NADPH + 3ATP (Pi = inorganic phosphate)
These components are then used to fuel stage two of the Calvin cycle to complete light independent reactions, which convert these components into glyceraldehyde 3-phosphate .This can then be used to form most carbohydrates such as glucose. As it is a cycle, most of the G3P made using this reaction will be used to regenerate the original materials which are used to convert additional CO2 and H2O into G3P.
3 CO2 + 6 NADPH + 5 H2O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi
Okay, I suppose that is a little complicated, after all .
This following schematic demonstrates the sum of all needed parts and products in order to produce one molecule of G3P as indicated by the equation above.
One
very important protein in this equation, which helps during carbon
fixation is called RuBisCO which is one of if not the most abundant enzymes on earth, as while it is biologically important in these
reactions, it is also exceptionally slow for an enzyme of its nature.
RuBisCo can only fix 3-10 molecules every second per enzyme, which means
great masses of it must be produced by the plant to keep up production.
The picture to the left is an example of the interesting structure of RuBisCO, which has remained dominant in its role despite its seemingly inefficient processing of molecules.