The Photosynthesis System of our Planet Earth

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.

1. PHOTOSYNTHESIS JUNE SPENCER CERA College of Agricultural Sciences and Technology, Isabela State University, Cabagan, Isabela, Philippines 2024

2. What is photosynthesis? This is a biochemical process in phototrophs (plants, algae, cyanobacteria) to make their food (glucose). It involves two reactions: Light reactions that occur in the chloroplast thylakoid membrane (splitting water into oxygen (O2), protons and electrons), then transferring of protons and electrons through the thylakoid membrane to create adenosine triphosphate (ATP) and nicotinamide-adenine dinucleotide phosphate (NADPH); The energy storage molecules (ATP and NADPH) then be utilized by enzymes of the Calvin-Benson cycle, also known as dark reactions, which convert the carbon dioxide (CO2) into carbohydrates in the chloroplast stroma.

3. Reactions Involved Light Reactions: 2H 2 O + light → O 2 + 4H + + 4e − Dark Reactions: CO 2 + 4H + + 4e − → CH 2 O + H 2 O Overall: H 2 O + light + CO 2 → CH 2 O + O 2

4. Photosynthesis: A Redox Process 6CO 2 + 12H 2 O → C 6 H 12 O 6 + 6H 2 O 2 + 6O 2 Reduction Oxidation The water molecules are split apart. The electrons and hydrogen ions are removed, leaving oxygen gas. The electrons and hydrogen ions are transferred to carbon dioxide to produce sugar.

5. Site of Photosynthesis Leaves – plant organ that evolved to expose the area of green tissue for light and CO 2 entry through stomata. Leaf Cross-section of leaf A B Photo B by Johnson, M.P. (2016)

6. Chlorophyll The green pigment found in chloroplast. Photo by Tertre , E. (2014)

7. Phototrophs Living organisms that can do the process of photosynthesis. Plants Cyanobacteria Algae

8. References Aung, L. L., Tertre , E., Worasith , N., Suksabye , P., Thiravetyan , P., & Christidis , G. (2014). The capacity of activated kaolins to remove colour pigments from rice bran oil: the effects of acid concentration and pre-heating prior to activation. Clay Minerals, 49(4), 513-526. Johnson, M.P. (2016). Photosynthesis. Essays in Biochemistry. 60(3), 225-273. DOI: 10.1042/EBC20160016