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The following is a breakdown of the energetics of the photosynthesis process from Photosynthesis by Hall and Rao: [6]. Starting with the solar spectrum falling on a leaf, 47% lost due to photons outside the 400–700 nm active range (chlorophyll uses photons between 400 and 700 nm, extracting the energy of one 700 nm photon from each one)
The pair of P700* - P700 + has an electric potential of about −1.2 volts. The reaction center is made of two chlorophyll molecules and is therefore referred to as a dimer. [11] The dimer is thought to be composed of one chlorophyll a molecule and one chlorophyll a′ molecule. However, if P700 forms a complex with other antenna molecules, it ...
P870 → P870 * → ubiquinone → cyt bc 1 → cyt c 2 → P870. This is a cyclic process in which electrons are removed from an excited chlorophyll molecule (bacteriochlorophyll; P870), passed through an electron transport chain to a proton pump (cytochrome bc 1 complex; similar to the chloroplastic one), and then returned to the chlorophyll ...
The daily light integral (DLI) is the number of photosynthetically active photons (photons in the PAR range) accumulated in a square meter over the course of a day. It is a function of photosynthetic light intensity and duration (day length) and is usually expressed as moles of light (mol photons) per square meter (m −2) per day (d −1), or: mol·m −2 ·d −1.
Chlorophyll f was announced to be present in cyanobacteria and other oxygenic microorganisms that form stromatolites in 2010; [13] [14] a molecular formula of C 55 H 70 O 6 N 4 Mg and a structure of (2-formyl)-chlorophyll a were deduced based on NMR, optical and mass spectra.
Non-photochemical quenching (NPQ) is a mechanism employed by plants and algae to protect themselves from the adverse effects of high light intensity.It involves the quenching of singlet excited state chlorophylls (Chl) via enhanced internal conversion to the ground state (non-radiative decay), thus harmlessly dissipating excess excitation energy as heat through molecular vibrations.
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. The antenna pigments are predominantly chlorophyll b, xanthophylls, and ...
First, a photon is absorbed by chlorophyll pigments surrounding the reaction core center of photosystem II. The light excites an electron in the pigment P680 at the core of photosystem II, which is transferred to the primary electron acceptor, pheophytin , leaving behind P680 + .