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Symmetry breaking in biology is the process by which uniformity is broken, or the number of points to view invariance are reduced, to generate a more structured and improbable state. [1] Symmetry breaking is the event where symmetry along a particular axis is lost to establish a polarity.
In developmental biology, left-right asymmetry (LR asymmetry) is the process in early embryonic development that breaks the normal symmetry in the bilateral embryo.In vertebrates, left-right asymmetry is established early in development at a structure called the left-right organizer (the name of which varies between species) and leads to activation of different signalling pathways on the left ...
Symmetry breaking occurs at several different levels in order to generate the anatomical asymmetry which we observe. These levels include asymmetric gene expression, protein expression, and activity of cells. For example, left–right asymmetry in mammals has been investigated extensively in the embryos of mice. Such studies have led to support ...
Single prime ( ' ) and double prime ( '' ) superscripts denote symmetry and antisymmetry, respectively, with respect to a horizontal mirror plane σ h, one perpendicular to the principal rotation axis. All but the two rightmost columns correspond to the symmetry operations which are invariant in the group. In the case of sets of similar ...
The syndrome is defined by the presence of at least one extra X chromosome in addition to a Y chromosome, yielding a total of 47 or more chromosomes rather than the usual 46. Klinefelter syndrome occurs randomly. The extra X chromosome comes from the father and mother nearly equally.
For proper diagnosis of situs ambiguus, cardiac and non-cardiac features must be evaluated. Diagnostic criteria for atrial isomerism includes observation of symmetry of thoracic visceral organs upon echocardiogram, arrhythmia upon electrocardiogram, and chest x-ray for confirmation of the heart's location across the left-right axis.
Walter Sutton (left) and Theodor Boveri (right) independently developed different parts of the chromosome theory of inheritance in 1902.. The Boveri–Sutton chromosome theory (also known as the chromosome theory of inheritance or the Sutton–Boveri theory) is a fundamental unifying theory of genetics which identifies chromosomes as the carriers of genetic material.
Like many other medical conditions, obesity is the result of an interplay between environmental and genetic factors. [2] [3] Studies have identified variants in several genes that may contribute to weight gain and body fat distribution, although only in a few cases are genes the primary cause of obesity.