Хлорофилл a: құрылымы, қасиеттері және фотосинтездегі ролі

Chembox
| Name = Chlorophyll a
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 451983978
| ImageFile = Chlorophyll a. svg
| ImageSize =
| ImageName = Structure of chlorophyll a
| IUPACName = Chlorophyll a
| SystematicName = Magnesium [methyl (3S,4S,21R) 14 ethyl 4,8,13,18 tetramethyl 20 oxo 3 (3 oxo 3 [(2E,7R,11R) 3,7,11,15 tetramethyl 2 hexadecen 1 yl]oxy}propyl) 9 vinyl 21 phorbinecarboxylatato(2−) κ2N,N′]
| OtherNames = α Chlorophyll
|Section1=
|Section2=Chembox Properties
| C=55 | H=72 | Mg=1 | O=5 | N=4
| Appearance = Green
| Odor = Odorless
| Density = 1.079 g/cm3 decomposes
| Solubility = Insoluble
| SolubleOther = Very soluble in ethanol, ether Soluble in ligroin, Chlorophyll does not reflect light but chlorophyll containing tissues appear green because green light is diffusively reflected by structures like cell walls. This photosynthetic pigment is essential for photosynthesis in eukaryotes, cyanobacteria and prochlorophytes because of its role as primary electron donor in the electron transport chain. Chlorophyll a also transfers resonance energy in the antenna complex, ending in the reaction center where specific chlorophylls P680 and P700 are located.

Chlorophyll a is essential for most photosynthetic organisms to release chemical energy but is not the only pigment that can be used for photosynthesis. All oxygenic photosynthetic organisms use chlorophyll a, but differ in accessory pigments like chlorophyll b. These organisms use bacteriochlorophyll and some chlorophyll a but do not produce oxygen. The porphyrin ring of bacteriochlorophyll is saturated, and lacking alternation of double and single bonds causing variation in absorption of light.

Side chains are attached to the chlorin ring of the various chlorophyll molecules. Different side chains characterize each type of chlorophyll molecule, and alters the absorption spectrum of light. For instance, the only difference between chlorophyll a and chlorophyll b is that chlorophyll b has an aldehyde instead of a methyl group at the C 7 position.

Chlorophyll a absorbs light within the violet, blue and red wavelengths. Accessory photosynthetic pigments broaden the spectrum of light absorbed, increasing the range of wavelengths that can be used in photosynthesis. P680 and P700 are the primary electron donors to the electron transport chain. These two systems are different in their redox potentials for one electron oxidation. The Em for P700 is approximately 500mV, while the Em for P680 is approximately 1,100 1,200 mV.