| X chromosome inactivation
|
| In female mammalian embryos, the early random
inactivation of the genes on one of the X chromosomes, leading to
mosaicism for functions coded by heterozygous X-linked genes (See
dosage compensation and Barr body). |
| X hyperactivation |
| In Drosophila the process by which the structural
genes of the male X chromosome are transcribed at the same rate
as the two X chromosomes of the female combined. |
| X linkage |
| The inheritance pattern of genes found on
the X chromosome but not on the Y. |
| X-and-Y linkage |
| The inheritance pattern of genes found on
both the X and Y chromosomes (rare). |
| X-inactivation centre
(XIC) |
| locus on the X chromosome in mammals at
which inactivation is initiated. |
| X-ray crystallography
|
| A technique, using X rays, to determine
the atomic structure of molecules that have been crystallized. A
technique for deducing molecular structure by aiming a beam of X
rays at a crystal of the test compound and measuring the scatter
of rays. |
| X:A ratio |
| The ratio between the X chromosome and the
number of sets of autosomes. |
| xeroderma pigmentosum
|
| A disease in human beings caused by a defect
in the UV mutation repair system. |
