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The scientist Charles Barnes first used the word 'photosynthesis' in 1893. This word is taken from two Greek words, photos, which means light, and synthesis, which in chemistry means making a substance by combining simpler substances. So, in the presence of light, synthesis of food is called 'photosynthesis'.
NADH dehydrogenase → plastoquinol → b 6 f → cyt c 6 → cyt aa 3 → O 2. where the mobile electron carriers are plastoquinol and cytochrome c 6, while the proton pumps are NADH dehydrogenase, cyt b 6 f and cytochrome aa 3 (member of the COX3 family). Cyanobacteria are the only bacteria that produce oxygen during photosynthesis.
Photosynthesis usually refers to oxygenic photosynthesis, a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen , cellulose and starches .
Light-dependent reactions of photosynthesis at the thylakoid membrane. Photosystems are functional and structural units of protein complexes involved in photosynthesis. Together they carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons.
The enzyme phosphoglycerate kinase catalyses the phosphorylation of 3-PGA by ATP (which was produced in the light-dependent stage). 1,3-Bisphosphoglycerate (glycerate-1,3-bisphosphate) and ADP are the products. (However, note that two 3-PGAs are produced for every CO 2 that enters the cycle, so this step utilizes two ATP per CO 2 fixed ...
The following is a breakdown of the energetics of the photosynthesis process from Photosynthesis by Hall and Rao: [6]. Starting with the solar spectrum falling on a leaf, 47% lost due to photons outside the 400–700 nm active range (chlorophyll uses photons between 400 and 700 nm, extracting the energy of one 700 nm photon from each one)
P700 receives energy from antenna molecules and uses the energy from each photon to raise an electron to a higher energy level (P700*). These electrons are moved in pairs in an oxidation/reduction process from P700* to electron acceptors, leaving behind P700 +. The pair of P700* - P700 + has an electric potential of about −1.2 volts.
The evolution of oxygen during the light-dependent steps in photosynthesis (Hill reaction) was proposed and proven by British biochemist Robin Hill. He demonstrated that isolated chloroplasts would make oxygen (O 2) but not fix carbon dioxide (CO 2). This is evidence that the light and dark reactions occur at different sites within the cell. [1 ...