Photosynthesis can be broken down into the light-dependent reactions (which this entire section will cover), and the light-independent reactions (covered in the next section). Both occur within the chloroplasts of cyanobacteria, plants, and algae. Fig.…More »

Drilling Down In the cells of plants and algae are structures called chloroplasts (Fig. 1). (And there is much evidence that these chloroplasts were once independently-living cyanobacteria.) Chloroplasts have an inner and outer membrane (just like…More »

Electron Flow Chemical reactions involve atoms and molecules, but chemistry at its heart is really the study of the electron flow between those atoms and molecules when these react. Similarly, biochemistry at its heart is the study of the electron flow…More »

Drilling Down There are two types of photosynthesis: anoxygenic and oxygenic. Anoxygenic photosynthesis was the first to appear on Earth around 3.5 billion years ago, was and is performed solely by several groups of bacteria to this day, and…More »

Overview Photosystem I (PSI) is the second of two photosystems, and the third of four major protein complexes in the thylakoids of cyanobacteria and chloroplasts. (A protein complex is a unit of several protein subunits.) The thylakoids are where…More »

Electron Flow All life is driven by electron flows through incredibly involved pathways called ‘electron transport chains’. (That it happens at all is just awe-inspiring!) All such pathways begin with a primary electron donor and end with a…More »

A Summary of Oxygenic Photosynthesis to Date Oxygenic photosynthesis produces oxygen gas (O2), and is performed by plants, algae and cyanobacteria. (Many other bacteria can photosynthesise, but these are anoxygenic photosynthesisers, typically producing…More »