A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.

Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell […]

‘When you hear hoof beats, think of horses, not zebras.’ For example, when someone develops a mild transient cough, a virus infection is the most logical and likely cause, and tuberculosis is a zebra.

A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its […]

A technique in which a woman’s egg is fertilized outside the body, then implanted in one of her fallopian tubes. This technique is one of the methods used to overcome infertility, the inability of couples to produce offspring on their own. First, the egg and the male sperm needed to fertilize it are harvested. Then […]

DNA sequences that are repeated in the genome. These sequences do not code for protein. One class termed highly repetitive DNA consists of short sequences, 5-100 nucleotides, repeated thousands of times in a single stretch and includes satellite DNA. Another class termed moderately repetitive DNA consists of longer sequences, about 150-300 nucleotides, dispersed evenly throughout […]

A type of plague that is spread by ground squirrels and other wild rodents. Sylvatic plague is sometimes seen in the western portion of the US.

Fahrenheit: Thermometer scale in which the freezing point of water is 32°F and the boiling point of water 212°F. The Fahrenheit scale is still obstinately in use in the US. This anachronism requires conversion from Centigrade (°C) to Fahrenheit (°F), and vice versa. One degree °C = (5/9)(°F – 32). One degree °F = (9/5)(°C) […]

Alpha helix: The coiled structure of many proteins consisting of a single chain of amino acids stabilized by hydrogen bonds. The alpha helix was first proposed by Linus Pauling and Robert Corey in a brilliant series of paper in the early 1950s. It is also known as the Pauling-Corey helix. See also: Pauling, Linus.

Dracunculiasis: The disease is Called gotten-This term is essentially slang and should not be used.