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An inversion is a chromosome rearrangement in which a segment of a chromosome becomes inverted within its original position. An inversion occurs when a chromosome undergoes a two breaks within the chromosomal arm, and the segment between the two breaks inserts itself in the opposite direction in the same chromosome arm.
The increased strength of the face inversion effect over time supports the perceptual learning hypothesis, since more experience with faces results in increased susceptibility to the effect. [20] The more familiar a particular type of face (e.g. human or dog) is, the more susceptible one is to the face inversion effect for that face.
This theory is lacking in theoretical support because mutations that cause a large reduction in fitness can only be fixed through genetic drift in small, inbred populations, and the effects of chromosomal rearrangements on fitness are unpredictable and vary greatly in plant and animal species.
Inversion was first noted in 1822 by the French zoologist Étienne Geoffroy Saint-Hilaire, when he dissected a crayfish (an arthropod) and compared it with the vertebrate body plan. The idea was heavily criticised, but periodically resurfaced, and is now supported by some molecular embryologists.
Known human disorders include Charcot–Marie–Tooth disease type 1A, which may be caused by duplication of the gene encoding peripheral myelin protein 22 (PMP22) on chromosome 17. Inversions : A portion of the chromosome has broken off, turned upside down, and reattached, therefore the genetic material is inverted.
Animals only rarely exhibit inbreeding avoidance. [1] The inbreeding avoidance hypothesis posits that certain mechanisms develop within a species, or within a given population of a species, as a result of assortative mating and natural and sexual selection , in order to prevent breeding among related individuals.
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Pyramidal inversion in nitrogen and amines is known as nitrogen inversion. [8] It is a rapid oscillation of the nitrogen atom and substituents, the nitrogen "moving" through the plane formed by the substituents (although the substituents also move - in the other direction); [ 9 ] the molecule passing through a planar transition state . [ 10 ]