inversion

1. A turning inward, upside down, or in any direction contrary to the existing one. 2. Conversion of a disaccharide or polysaccharide by hydrolysis into a monosaccharide; specifically, the hydrolysis of sucrose to d-glucose and d-fructose; so called because of the change in optical rotation. 3. Alteration of a DNA molecule made by removing a fragment, reversing its orientation, and putting it back into place. 4. Heat-induced transition of silica, in which the quartz tridymite or cristobalite changes its physical properties as to thermal expansion. 5. Conversion of a chiral center into its mirror image. [L. inverto, pp. -versus, to turn upside down, to turn about]

- i. of chromosomes a chromosome aberration resulting from a double break in a segment of the chromosome, with end for end rotation of the fragment between the fracture lines, and refusion of the fragments; this results in reversal of the order of genes in that segment.

- paracentric i. i. in a chromosome of a single segment in which the centromere is not included.

- pericentric i. i. in a chromosome of a single segment that includes the centromere.

- i. of the uterus a turning of the uterus inside out, usually following childbirth.

- visceral i. SYN: situs inversus viscerum.

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in·ver·sion in-'vər-zhən, -shən n

1) a reversal of position, order, form, or relationship: as

a) a dislocation of a bodily structure in which it is turned partially or wholly inside out <\inversion of the uterus>

b) the condition (as of the foot) of being turned or rotated inward compare EVERSION (2)

c) RETROFLEXION

d) a breaking off of a chromosome section and its subsequent reattachment in inverted position also a chromosomal section that has undergone this process

2 a) the conversion of dextrorotatory sucrose into a levorotatory mixture of glucose and fructose

b) a change from one stereochemical figuration at a chiral center in a usu. organic molecule to the opposite configuration that is brought about by a reaction in which a substitution of one group is made for a different group

3) HOMOSEXUALITY

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n.

1. the turning inwards or inside-out of a part or organ: commonly applied to the state of the uterus after childbirth when its upper part is pulled through the cervical canal.

2. a chromosome mutation in which a block of genes within a chromosome are in reverse order, due to that section of the chromosome becoming inverted. The centromere may be included in the inverted segment (pericentric inversion) or not (paracentric inversion).

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in·ver·sion (in-vurґzhən) [L. inversio; in into +vertere to turn] 1. a turning inward, inside out, upside down, or other reversal of the normal relation of a part. 2. in genetics, a chromosomal aberration caused by the inverted reunion of a chromosome segment after breakage of a chromosome at two points, resulting in a change in sequence of genes or nucleotides; e.g., the sequence abcdefg may be inverted to abfedcg. See illustration at aberration.

Inversion and eversion of the foot.