photosystemn.

Brit.

/ˈfəʊtəʊˌsɪstᵻm/, U.S.

/ˈfoʊdoʊˌsɪstəm/

Origin: Formed within English, by compounding. Etymons: photo- comb. form, system n.

Etymology: < photo- comb. form + system n.

1. In Joly's theory of photographic development: a molecular system which has been ionized by the action of light. rare.

ΚΠ

1914 J. Joly in Proc. Royal Soc. B. 88 263 As a consequence of the chemical reaction..between the developer and the ionised photo-system the metallic atom is liberated.

2. Either of two biochemical mechanisms forming part of the process of photosynthesis in plants, by which light of particular wavelengths is absorbed and its energy converted into chemical energy for use in biosynthesis (usually distinguished as photosystem I and photosystem II). Also: either of the large membrane-bound complexes of proteins, chlorophyll, carotenoids, and other molecules in which these processes occur.

ΘΚΠ

the world > plants > by nutrition or respiration > [noun] > photosynthesis

photosyntax1893

photosynthesis1893

phototrophy1947

photosystem1964

1961 L. N. M. Duysens et al. in Nature 6 May 510/1 It followed that at least two photochemical pigment systems are present.

1961 L. N. M. Duysens et al. in Nature 6 May 511/2 In order to bring about photosynthesis, systems 1 and 2 must both be excited.]

1964 Science 24 Jan. 390/2 There appear to be two photosystems. One (designated ‘II’ by L. N. M. Duysens) contains part of the total of chlorophyll a and a high proportion of the accessory pigments; the other (‘I’) contains most of the long wavelength absorbing and nonfluorescent chlorophyll a.

1973 J. J. Wolken in L. P. Miller Phytochem. I. ii. 26 The low efficiency of the far-red (beyond 680 nm) would require another pigment-complex absorbing below 680 nm, which has been designated as Photosystem II.

1991 D. T. Sawyer Oxygen Chem. i. 9 The conventional wisdom for the mechanism of photosynthesis includes two independent photosystems that pump reducing equivalents from water (photosystem II) through a cascade of steps controlled by enzymes to a CO₂ reduction center (photosystem I).

This entry has been updated (OED Third Edition, March 2006; most recently modified version published online March 2022).

单词	photosystem
释义	photosystemn. Brit. /ˈfəʊtəʊˌsɪstᵻm/, U.S. /ˈfoʊdoʊˌsɪstəm/ Origin: Formed within English, by compounding. Etymons: photo- comb. form, system n. Etymology: < photo- comb. form + system n. 1. In Joly's theory of photographic development: a molecular system which has been ionized by the action of light. rare. ΚΠ 1914 J. Joly in Proc. Royal Soc. B. 88 263 As a consequence of the chemical reaction..between the developer and the ionised photo-system the metallic atom is liberated. 2. Either of two biochemical mechanisms forming part of the process of photosynthesis in plants, by which light of particular wavelengths is absorbed and its energy converted into chemical energy for use in biosynthesis (usually distinguished as photosystem I and photosystem II). Also: either of the large membrane-bound complexes of proteins, chlorophyll, carotenoids, and other molecules in which these processes occur. ΘΚΠ the world > plants > by nutrition or respiration > [noun] > photosynthesis photosyntax1893 photosynthesis1893 phototrophy1947 photosystem1964 1961 L. N. M. Duysens et al. in Nature 6 May 510/1 It followed that at least two photochemical pigment systems are present. 1961 L. N. M. Duysens et al. in Nature 6 May 511/2 In order to bring about photosynthesis, systems 1 and 2 must both be excited.] 1964 Science 24 Jan. 390/2 There appear to be two photosystems. One (designated ‘II’ by L. N. M. Duysens) contains part of the total of chlorophyll a and a high proportion of the accessory pigments; the other (‘I’) contains most of the long wavelength absorbing and nonfluorescent chlorophyll a. 1973 J. J. Wolken in L. P. Miller Phytochem. I. ii. 26 The low efficiency of the far-red (beyond 680 nm) would require another pigment-complex absorbing below 680 nm, which has been designated as Photosystem II. 1991 D. T. Sawyer Oxygen Chem. i. 9 The conventional wisdom for the mechanism of photosynthesis includes two independent photosystems that pump reducing equivalents from water (photosystem II) through a cascade of steps controlled by enzymes to a CO₂ reduction center (photosystem I). This entry has been updated (OED Third Edition, March 2006; most recently modified version published online March 2022). < n.1914
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