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In higher plants thylakoids are organized into a granum-stroma membrane assembly. A granum (plural grana) is a stack of thylakoid discs. 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 ...
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.
A proton gradient is created across the thylakoid membrane (6) as protons (3) are transported from the chloroplast stroma (4) to the thylakoid lumen (5). Through chemiosmosis, ATP (9) is produced where ATP synthase (1) binds an inorganic phosphate group (8) to an ADP molecule (7).
Within the envelope membranes, in the region called the stroma, there is a system of interconnecting flattened membrane compartments, called the thylakoids.The thylakoid membrane is quite similar in lipid composition to the inner envelope membrane, containing 78% galactolipids, 15.5% phospholipids and 6.5% sulfolipids in spinach chloroplasts. [3]
Enclosed by the membrane is an aqueous fluid called the stroma. 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.
Reaction centers are multi-protein complexes found within the thylakoid membrane.. At the heart of a photosystem lies the reaction center, which is an enzyme that uses light to reduce and oxidize molecules (give off and take up electrons).
The electrons then pass through Cyt b 6 and Cyt f to plastocyanin, using energy from photosystem I to pump hydrogen ions (H +) into the thylakoid space. 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]
Chloroplasts are characterized by a system of membranes embedded in a hydrophobic proteinaceous matrix, or stroma. The basic unit of the membrane system is a flattened single vesicle called the thylakoid; thylakoids stack into grana. All the thylakoids of a granum are connected with each other, and the grana are connected by intergranal ...