Glossary

The basic number of chromosomes in a polyploid series, monoploid = x; diploid = 2x; triploid = 3x; etc.

A sex chromosome that usually occurs paired in each female cell and single in each male cell in species in which the male typically has two unlike cell chromosomes.

An essential technique for determining the three-dimensional structure of biological molecules. This information aids in the discovery of products that will interact with the biological molecule.

Industrial chemicals that have a chemical structure not found in natural compounds that may resist degradation by microorganisms.

Synthetic chemicals believed to be resistant to environmental degradation. A branch of biotechnology called bioremediation is seeking to develop biological methods to degrade such compounds.

Tissue or organs from an individual of one species transplanted into or grafted onto an organism of another species, genus, or family. A common example is the use of pig heart valves in humans.

Tissue or organs from an individual of one species transplanted into or grafted onto an organism of another species, genus, or family. A common example is the use of pig heart valves in humans.

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.

Refers to any procedure that involves the transplantation, implantation, or infusion into a human recipient of either, (a) live cells, tissues, or organs from a nonhuman animal source, or (b) human body fluids, cells, tissues or organs that have had ex vivo contact with live nonhuman animal cells, tissues, or organs. Xenotransplantation products include live cells, tissues, or organs used in xenotransplantation.

Cross-Linked Polyethylene

Extensible Markup Language

An asynchronous file transfer protocol initially developed for CP/M personal computers. First versions used a checksum to detect errors. Later versions use the more effective CRC method. Programs typically include both methods and drop back to checksum if CRC is not present at the other end. Xmodem transmits 128 byte blocks. Xmodem-1K improves speed by transmitting 1024 byte blocks. Xmodem-1K-G transmits without acknowledgment (for error free channels or when modems are self correcting), but transmission is cancelled upon any error.

Xenotropic Murine Leukemia Virus

Extreme Programming

X-ray Photoelectron Spectroscopy

Extruded Polystyrene

A surface-sensitive technique capable of detecting all elements with an atomic number greater than that of helium. ESCA provides data on the outermost several atomic layers of a material and has a sensitivity in the order of 0.5 atomic percent. A primary advantage of ESCA is that it can both determine and quantify the chemical state of the elements detected (i.e. metallic state or oxide state).

X-Ray Powder Diffraction