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Glossary Biotechnology Part: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 (Continued from previous part...) x The basic number of chromosomes in a polyploid series, monoploid = x; diploid = 2x; triploid = 3x; etc. xanthophyll (Gr. xanthos, yellowish brown + phyllon, leaf) A yellow chloroplast pigment. X-chromosome A chromosome associated with sex determination. In most animals, the female has two, and the male has one X chromosome. The opposite occurs in birds, in which the equivalent is the Z chromosome. xenia The immediate effect of pollen on some characters of the endosperm. xenobiotic A chemical compound that is not produced by living organisms; a manufactured chemical compound. xenotransplantation The transplantation of tissue from one species to another species, typically from non-human mammals to humans. This technology has become very important because of a worldwide shortage of human organs for humans requiring a new organ. The most popular non-human species involved in this technology is the pig. xerophyte (Gr. xeros, dry + phyton, a plant) A plant very resistant to drought or that lives in very dry places. X-linkage See X-linked. X-linked The presence of a gene on the X chromosome. a.k.a. X-linkage. X-linked disease A genetic disease caused by an allele at a locus on the X-chromosome. In X-linked recessive conditions, a normal female "carrier" passes on the allele on her X chromosome to an affected son. X-ray crystallography The deduction of crystal structure from analysis of the diffraction pattern of X-rays passing through a pure crystal of a substance. xylem (Gr. xylon, wood) A complex tissue specialized for efficient conduction of water and mineral nutrients in solution. Xylem may also function as a supporting tissue, particularly secondary xylem. (Continued on next part...)
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