Karyotype: the chromosome constitution of an individual. A photomicrograph of an individual's chromosomes arranged in a standard format showing the number, size, and shape of each chromosome type; used in low-resolution physical mapping to correlate gross chromosomal abnormalities with the characteristics of specific diseases.
Kegel Exercises: exercise named after Dr. Arnold Kegel, who first prescribed a specific set of pelvic-floor exercises to women in the 1940s. (see Pelvic Muscle Exercises).
keV: 1,000 eV.
Key Informant: person chosen to answer a survey on the grounds of a better knowledge and understanding of the issues under consideration.
Kidney: one of two paired urine-making organs that lie in the back behind the 13th rib. The principal function is to filter the blood to separate out waste products, which are combined with excess water to form urine.
Killer Cell (K Cell): sensitized T lymphocytes produce a helper factor that acts on the immunocompetent lymphoid cell to produce a population of cells, probably variants of the B cell, termed killer cells (K cells), which are able to attack tumor cells that have been exposed to a specific sensitizing antibody. Unlike in the usual humoral antibody (immunoglobulin) response, complement is not needed.
Killer T Cell: a T cell with a particular immune specificity and an endogenously produced receptor for antigen, capable of specifically killing its target cell after attachment to the target cell by this receptor. Also called cytotoxic T cell.
Kilobase (kb): unit of length for DNA fragments equal to 1000 nucleotides.
Knockout: deactivation of specific genes; used in laboratory organisms to study gene function. See also -- gene, locus, model organisms.
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