In the electron transfer chain, the conversion takes place at lower poten­tials, i. e., NAD/NAD+ to NADH/NADH+ between ±0.6 V, favorable at a pH higher than 7.0. But the process develops other energy-rich compounds, and thus, very little free energy in the form of heat is directly available.

1.7.1 Photosynthetic path

Cytosolic to mitochondrial compartments, the interconversions of pyru­vate to aspartate and to glutamate; malate to a-ketoglutarate; the energy produced is utilized to synthesize higher carbon compounds, ultimately to glucose or even polysaccharide and polynucleotide (genetic material) (see Fig. 1.5). Artificial culture of thylakoid or chloroplast, (only remains a possibility for academic purposes at present); cannot be commercially achieved as yet.

The most important achievement is the photolysis of water (see Fig. 1.6), i. e., production of proton to hydrogen, reduction of carbon dioxide, reduc­tion of nitrogenous material, and increase in nitrogenous and carbona­ceous biomass. Attempts have been made to utilize the energy-trapping process of the photosynthetic pigments of the plastoquinones at two stages: (1) Pigment II utilizes 680-700 nm, converts water to a more

Chloroplast

Heterocysts

H20— ►ATP, (NADPH), CO2

——— Carbohydrate

Biomass

Figure 1.5 Electron flow in biophotolysis.

hv o2

_______ _______________

Chloroplast ІУІУІУІУІУІУІУІУІУІУІУ/ІУ;

Figure 1.6 Separated photolytic chamber design.

energetic intermediate, and undergoes a change of +0.8 to —1.1 V. (2) Pigment I utilizes 700-730 nm, undergoing +0.5 to almost —1.4 V, production of hydrogen, oxidation of coenzyme, making electrons available.

Models can be created where direct tapping from the thylakoid mem­brane may be made possible. Electrochemical cells have been designed where living thylakoids are used and exposed to sunlight from which, through proper instrumentation, the energy can be tapped.