Search results
Results from the WOW.Com Content Network
Stroma, in botany, refers to the colorless fluid surrounding the grana within the chloroplast. [1] Within the stroma are grana (stacks of thylakoid), the sub-organelles where photosynthesis is started [2] before the chemical changes are completed in the stroma. [3] Photosynthesis occurs in two stages.
The photosynthesis process in chloroplasts begins when an electron of P680 of PSII attains a ... are transported from the chloroplast stroma (4) to the thylakoid ...
Embedded within the stroma are stacks of thylakoids (grana), which are the site of photosynthesis. The thylakoids appear as flattened disks. The thylakoid itself is enclosed by the thylakoid membrane, and within the enclosed volume is a lumen or thylakoid space.
Chloroplasts can have from 10 to 100 grana. Grana are connected by stroma thylakoids, also called intergranal thylakoids or lamellae. Grana thylakoids and stroma thylakoids can be distinguished by their different protein composition. Grana contribute to chloroplasts' large surface area to volume ratio.
Chloroplasts that are the product of secondary endosymbiosis may have additional membranes surrounding these three. [30] Inside the outer and inner chloroplast membranes is the chloroplast stroma, a semi-gel-like fluid [23] that makes up much of a chloroplast's volume, and in which the thylakoid system floats.
The Calvin cycle is present in all photosynthetic eukaryotes and also many photosynthetic bacteria. In plants, these reactions occur in the stroma, the fluid-filled region of a chloroplast outside the thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them.
In photosynthesis, the cytochrome b 6 f complex functions to mediate the transfer of electrons and of energy between the two photosynthetic reaction center complexes, Photosystem II and Photosystem I, while transferring protons from the chloroplast stroma across the thylakoid membrane into the lumen. [2]
This creates a H + gradient, making H + ions flow back into the stroma of the chloroplast, providing the energy for the (re)generation of ATP. [citation needed] The photosystem II complex replaced its lost electrons from H 2 O, so electrons are not returned to photosystem II as they would in the analogous cyclic pathway. Instead, they are ...