plant photosynthesis is a complex physical and biochemical process by which plants convert electromagnetic energy, which is in the sun, into chemical energy used in organic compounds.The basis of this process is a chain redox chemical reactions that result in the electrons are transferred from the donor-reducing agent, which is hydrogen, and water, to the acceptor, is an oxidant.This produces carbohydrates and O2 is released during the oxidation of water.
photosynthesis, plants have two consecutive stages.The first stage is called the light (photochemical).In this step, light quantum energy is converted into chemical energy for bonds energetic compounds, as well as universal reductant.In the second stage, having the name dark (metabolic) obtained from the chemical energy of a reducing agent and a universal pass loop for fixation and reduction of carbon dioxide, whereby carbohydrates are formed.Photosynthetic mechanism separates light and dark step not only in time but also in space.The light phase takes place in special energy conversion thylakoid membranes, while dark reactions take place either in the chloroplast stroma, or in the cytoplasm.
photosynthesis and respiration of plants is based on the absorption of light quanta, which is dominated by the chlorophyll absorption spectrum which includes the visible and neighbors to her infrared and ultraviolet regions.The main pigment for all plants to carry out photosynthesis is chlorophyll a.Green algae, mosses and vascular plants have also chlorophyll b, which extends the range of the light absorbed.Some species of algae also contain chlorophylls c and d.In addition to chlorophyll, the process of absorption of light also participate carotenoids and phycobilins.
After absorbing light comes photochemical step, which is attended by two types of photosystem I and II (PS1 and PS2).Each APS consists of the reaction center where charge separation occurs, electric transport chain, where the oxidation of electrons and a set of components that perform the processes by photooxidation of water and the regeneration of the reaction center.The reaction centers of quantum light energy is converted into chemical and more electrons move according to the gradient of the electrochemical potential, which is an electron-transport chain of photosynthesis.
Photosystem II type performs photooxidation reaction water, thereby forming the oxygen and the proton H +.In parallel, photosynthetic electron transport is the process of proton transfer from the chloroplast in intrathylakoid area.The reaction yields of ATP and NADPH, which are the primary products of photosynthesis.Next photosynthesis of plants constitutes the enzymatic reaction in which carbon dioxide derived from proteins, carbohydrates and fats.If the dark non-carbohydrate metabolism has directivity, the formed amino acids, organic compounds and proteins.
metabolic processes of the type of CO2 fixation are classified into C3, C4 and CAM photosynthesis.Wherein the carbohydrates, which are formed on the dark stage of photosynthesis in chloroplasts may be deposited in the form of the compounds starch, exit the chloroplast to form new cells to serve as a source of energy for metabolic reactions.
photosynthesis, plants use only 1-2 percent of the absorbed light energy.The intensity of the photosynthetic process affects the spectral composition and intensity of light, temperature, water treatment plants and mineral nutrition, the concentration of CO2 and O2, as well as other environmental factors.
