plectonemicadj.

Brit.

/ˌplɛktə(ʊ)ˈniːmɪk/, U.S.

/ˌplɛktoʊˈnimɪk/

Origin: A borrowing from Greek, combined with an English element. Etymons: Greek πλεκτός , νῆμα , -ic suffix.

Etymology: < ancient Greek πλεκτός twisted (see plectognath n. and adj.) + νῆμα thread (see nemato- comb. form) + -ic suffix (see quot. 1941 at main sense). Compare paranemic adj.

Chiefly Molecular Biology.

Of, relating to, or designating a structure formed by two or more similar helices coiled together side by side in such a way that they cannot be fully separated without being unwound. Cf. paranemic adj.

ΘΚΠ

the world > life > biology > physical aspects or shapes > shape > [adjective] > coil

paranemic1941

plectonemic1941

1941 A. H. Sparrow et al. in Canad. Jrnl. Res. C. 19 325 Kuwada..describes two types of double-stranded spirals: (1) orthospirals, which are formed when the two threads being coiled have one end free so that internal twisting does not occur; (2) anorthospirals, which result when two strands with both ends fixed are coiled together and in consequence have a twist compensating for each gyre of the spiral... Orthospirals are interlocked and cannot be separated without untwisting; anorthospirals are independent and can readily be pulled apart or fitted into each other... Instead of orthospiral ‘plectonemic’ (plektos = twisted) will be used as this has the advantage of indicating the relationship of the strands.

1950 Biol. Rev. 25 500 Until quite recently almost all observers were agreed that the plectonemic spiral was characteristic of mitosis and the paranemic of meiosis (meaning the first meiotic division).

1953 J. D. Watson & F. H. C. Crick in Cold Spring Harbor Symp. Quant. Biol. 18 129/2 We therefore believe that if a helical structure is present [in DNA], the relationship between the helices will be plectonemic.

1971 Nature 22 Jan. 241/1 Tropocollagen..consists of three protein chains with similar, specific and very characteristic amino-acid compositions, twisted into a plectonemic triple helix of about 100 turns.

1993 Nucleic Acids Res. 21 3653/1 RecA protein is able to promote formation of stable plectonemic joints.

Derivatives

plectoˈnemically adv.

ΘΚΠ

the world > life > biology > physical aspects or shapes > shape > [adverb] > coil

plectonemically1953

1953 Cold Spring Harbor Symp. Quantitative Biol. 18 128/2 Apart from breaking the chains there are only two sorts of ways to separate two chains coiled plectonemically.

2002 Ann. Rev. Genetics (Nexis) 1 Jan. 175 Supercoils that are stabilized by interactions with other molecules can be toroidal, but unstabilized supercoils commonly are plectonemically interwound.

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

单词	plectonemic
释义	plectonemicadj. Brit. /ˌplɛktə(ʊ)ˈniːmɪk/, U.S. /ˌplɛktoʊˈnimɪk/ Origin: A borrowing from Greek, combined with an English element. Etymons: Greek πλεκτός , νῆμα , -ic suffix. Etymology: < ancient Greek πλεκτός twisted (see plectognath n. and adj.) + νῆμα thread (see nemato- comb. form) + -ic suffix (see quot. 1941 at main sense). Compare paranemic adj. Chiefly Molecular Biology. Of, relating to, or designating a structure formed by two or more similar helices coiled together side by side in such a way that they cannot be fully separated without being unwound. Cf. paranemic adj. ΘΚΠ the world > life > biology > physical aspects or shapes > shape > [adjective] > coil paranemic1941 plectonemic1941 1941 A. H. Sparrow et al. in Canad. Jrnl. Res. C. 19 325 Kuwada..describes two types of double-stranded spirals: (1) orthospirals, which are formed when the two threads being coiled have one end free so that internal twisting does not occur; (2) anorthospirals, which result when two strands with both ends fixed are coiled together and in consequence have a twist compensating for each gyre of the spiral... Orthospirals are interlocked and cannot be separated without untwisting; anorthospirals are independent and can readily be pulled apart or fitted into each other... Instead of orthospiral ‘plectonemic’ (plektos = twisted) will be used as this has the advantage of indicating the relationship of the strands. 1950 Biol. Rev. 25 500 Until quite recently almost all observers were agreed that the plectonemic spiral was characteristic of mitosis and the paranemic of meiosis (meaning the first meiotic division). 1953 J. D. Watson & F. H. C. Crick in Cold Spring Harbor Symp. Quant. Biol. 18 129/2 We therefore believe that if a helical structure is present [in DNA], the relationship between the helices will be plectonemic. 1971 Nature 22 Jan. 241/1 Tropocollagen..consists of three protein chains with similar, specific and very characteristic amino-acid compositions, twisted into a plectonemic triple helix of about 100 turns. 1993 Nucleic Acids Res. 21 3653/1 RecA protein is able to promote formation of stable plectonemic joints. Derivatives plectoˈnemically adv. ΘΚΠ the world > life > biology > physical aspects or shapes > shape > [adverb] > coil plectonemically1953 1953 Cold Spring Harbor Symp. Quantitative Biol. 18 128/2 Apart from breaking the chains there are only two sorts of ways to separate two chains coiled plectonemically. 2002 Ann. Rev. Genetics (Nexis) 1 Jan. 175 Supercoils that are stabilized by interactions with other molecules can be toroidal, but unstabilized supercoils commonly are plectonemically interwound. This entry has been updated (OED Third Edition, September 2006; most recently modified version published online March 2022). < adj.1941
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