Photosystems are multiprotein complexes that form the functional units of photosynthesis in plants, algae, and cyanobacteria. They are found embedded in the membrane of tiny sac-like structures called thylakoids placed inside the chloroplast.
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment...

The light reactions of photosynthesis assume a linear flow of electrons from water to NADP+. During this process, light energy drives the splitting of water molecules to produce oxygen. However, oxidation of water molecules is a thermodynamically unfavorable reaction and requires a strong oxidizing agent. This is accomplished by the first product of light reactions: oxidized P680 (or P680+), the most powerful oxidizing agent known in biology. The oxidized P680 that acquires an electron from the...

Oxygenic photosynthesis is a fundamental process in which light energy is harnessed to drive the oxidation of water, leading to the production of molecular oxygen (O₂), adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH). This process is essential for sustaining aerobic life on Earth and is primarily carried out by cyanobacteria, algae, and plants. The core of oxygenic photosynthesis lies in the thylakoid membranes, where chlorophyll pigments facilitate...

Photosynthesis is a multipart, biochemical process that occurs in plants as well as in some bacteria. It captures carbon dioxide and solar energy to produce glucose. Glucose stores chemical energy in the form of carbohydrates. The overall biochemical formula of photosynthesis is 6 CO2 + 6 H2O + Light energy → C6H12O6 + 6 O2. Photosynthesis releases oxygen into the atmosphere and is largely responsible for maintaining the Earth’s atmospheric oxygen content.

Overview

Anoxygenic photosynthesis is a phototrophic process that captures light energy to drive carbon fixation without producing molecular oxygen. Unlike oxygenic photosynthesis, which utilizes water as an electron donor and releases oxygen, anoxygenic phototrophs use alternative electron donors such as hydrogen sulfide (H₂S), elemental sulfur (S⁰), or thiosulfate (S₂O₃²⁻). This process is carried out by diverse groups of bacteria, including purple bacteria, green...