The biochemical capacity to use water as the source for electrons in photosynthesis evolved once, in a common ancestor of extant cyanobacteria (formerly called blue-green algae). The geological record indicates that this transforming event took place early in Earth's history, at least 2450–2320 million years ago (Ma), and, it is speculated, much earlier.
Jan 19, 2024
6 min
The cyclic reaction is similar to that of the non-cyclic but differs in that it generates only ATP, and no reduced NADP (NADPH) is created. The cyclic reaction takes place only at photosystem I. Once the electron is displaced from the photosystem, the electron is passed down the electron acceptor molecules and returns to photosystem I, from where it was emitted, hence the name cyclic reaction. Also, The 2023 RORRY Awards Preview. Only $3 every other week to get full RARR access 24-7.
Nov 12, 2023
8 min
Polysiphonia denudata is erect with repeatedly branched axes. Each branch consists of a central axis with 5 to 7 elongated pericentral cells all of the same length. Cortication occurs lower down, these corticating cells grow down in the grooves between the pericentral cells.
Sep 17, 2023
5 min