paracentricadj.1
/ˌparəˈsɛntrɪk/, U.S. /ˌpɛrəˈsɛntrɪk/ Astronomy and Mathematics. Now chiefly historical.
Designating or relating to motion towards or away from an attracting centre, such as was supposed by Leibniz to form part (along with harmonic circulation) of the motion of the planets. Later also: designating simple motion about a centre.
ΚΠ
1704 C. Hayes Treat. Fluxions 293 Paracentric motion of Impetus is so much as the revolving Body approaches nearer to or recedes farther from the Center of Attraction.
1715 tr. D. Gregory Elements Astron. I. i. §77. 175 The intire Motion of the Planet (namely the Paracentric,) arises from a double Curve, namely, the excussory impression of Circulation and the Sun's attraction (or what is equivalent) compounded together.
1797 Monthly Mag. 3 128 If a slender rod AC revolve round the point C, as a centre,..the centrifugal force arising from the paracentric velocity of the rod [etc.].
1855 A. W. Smith Elem. Treat. Mech. 226 The paracentric force is the difference between the centrifugal and centripetal forces.
1908 Amer. Math. Monthly 15 43 Given the para-centric acceleration..and the angular velocity..to determine the equation of the orbit.
1990 Isis 81 31 His [sc. Leibniz's] equation of paracentric motion.
Derivatives
ΚΠ
1715 G. Cheyne Philos. Princ. Relig. (ed. 2) i. ii. 32 The Paracentrical Motion is compounded of two others, viz...[that] whereby all Bodies moving in a Curve, endeavour to recede from the Center by the Tangent, and the Attraction of the Sun or the Gravitation of the Planet toward it.
This entry has been updated (OED Third Edition, June 2005; most recently modified version published online March 2022).
paracentricadj.2
/ˌparəˈsɛntrɪk/, U.S. /ˌpɛrəˈsɛntrɪk/ Cell Biology.
Involving only the part of a chromosome to one side of the centromere. Chiefly in paracentric inversion n. a genetic mutation in which a chromosome segment on one side of the centromere is rotated through 180 degrees. Cf. pericentric adj. 3.
ΘΚΠ
the world > life > biology > biological processes > genetic activity > genetic components > [adjective] > chromosome > centromere
acentric1899
telomitic1917
centric1937
paracentric1938
pericentric1938
metacentric1939
telocentric1939
centromeric1941
multicentric1941
polycentric1943
acrocentric1945
subtelocentric1954
submetacentric1957
subacrocentric1960
1938 H. J. Muller in Collecting Net 13 187/2 If the breaks were to one side of the centromere, the inversion may be termed ‘paracentric’, and it will be noted that the proportions of the two arms, and hence the general shape of the chromosome as seen at mitosis, is not changed. But if the breaks included the centromere between them, being ‘pericentric’, the mitotic chromosome will have the relative sizes of its two arms altered, except in the special case in which the two distal sections are sensibly equal in size.
1957 C. P. Swanson Cytol. & Cytogenetics xv. 485 Paracentric inversions are by far the most common type of aberration found in natural populations.
1983 J. R. S. Fincham Genetics vi. 155 Paracentric inversions are of great importance in experimental Drosophila genetics.
2000 Crop Sci. (Nexis) 40 683 Crossing over within paracentric loops alone..leads to the appearance of chromatin bridges and fragments at anaphase I and II, and subsequently to aborted spores.
This entry has been updated (OED Third Edition, June 2005; most recently modified version published online March 2022).
<
adj.11704adj.21938