Search results
Results from the WOW.Com Content Network
Different side chains characterize each type of chlorophyll molecule, and alters the absorption spectrum of light. [10] [11] 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. [11]
The absorption peaks of chlorophyll a are at 465 nm and 665 nm. Chlorophyll a fluoresces at 673 nm (maximum) and 726 nm. The peak molar absorption coefficient of chlorophyll a exceeds 10 5 M −1 cm −1, which is among the highest for small-molecule organic compounds. [26]
The antenna pigments are predominantly chlorophyll b, xanthophylls, and carotenes. Chlorophyll a is known as the core pigment. Their absorption spectra are non-overlapping and broaden the range of light that can be absorbed in photosynthesis. The carotenoids have another role as an antioxidant to prevent photo-oxidative damage of chlorophyll ...
P680, or photosystem II primary donor, is the reaction-center chlorophyll a molecular dimer associated with photosystem II in plants, algae, and cyanobacteria, and central to oxygenic photosynthesis. Etymology
Chlorophyll a is the most common of the six, present in every plant that performs photosynthesis. Each pigment absorbs light more efficiently in a different part of the electromagnetic spectrum. Chlorophyll a absorbs well in the ranges of 400–450 nm and at 650–700 nm; chlorophyll b at 450–500 nm and at 600–650 nm. Xanthophyll absorbs ...
The different chlorophyll and non-chlorophyll pigments associated with the photosystems all have different absorption spectra, either because the spectra of the different chlorophyll pigments are modified by their local protein environment or because the accessory pigments have intrinsic structural differences.
Absorbance spectra of free chlorophyll a (blue) and b (red) in a solvent. The action spectra of chlorophyll molecules are slightly modified in vivo depending on specific pigment-protein interactions. An action spectrum is a graph of the rate of biological effectiveness plotted against wavelength of light. [1]
In these two examples, a metal is complexed at the center of a tetrapyrrole macrocycle ring: the metal being iron in the heme group (iron in a porphyrin ring) of hemoglobin, or magnesium complexed in a chlorin-type ring in the case of chlorophyll. The highly conjugated pi-bonding system of the macrocycle ring absorbs visible light.