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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.
In chemistry, many reactions depend on the absorption of photons to provide the energy needed to overcome the activation energy barrier and hence can be labelled light-dependent. Such reactions range from the silver halide reactions used in photographic film to the creation and destruction of ozone in the upper atmosphere .
Cornelis Van Niel made key discoveries explaining the chemistry of photosynthesis. By studying purple sulfur bacteria and green bacteria, he was the first to demonstrate that photosynthesis is a light-dependent redox reaction in which hydrogen reduces (donates its atoms as electrons and protons to) carbon dioxide.
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.
Photosynthesis is a process where light is absorbed or harvested by pigment protein complexes which are able to turn sunlight into energy. [5] Absorption of a photon by a molecule takes place when pigment protein complexes harvest sunlight leading to electronic excitation delivered to the reaction centre where the process of charge separation can take place.
The light-harvesting complex (or antenna complex; LH or LHC) is an array of protein and chlorophyll molecules embedded in the thylakoid membrane of plants and cyanobacteria, which transfer light energy to one chlorophyll a molecule at the reaction center of a photosystem.
An example spangram with corresponding theme words: PEAR, FRUIT, BANANA, APPLE, etc. Need a hint? Find non-theme words to get hints. For every 3 non-theme words you find, you earn a hint.
It is possible to introduce an artificial electron acceptor into the light reaction, such as a dye that changes color when it is reduced. These are known as Hill reagents. These dyes permitted the finding of electron transport chains during photosynthesis. Dichlorophenolindophenol (DCPIP), an example of these dyes, is widely used by experimenters.