K

Karyotype:

A photomicrograph of an individuals 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.

Kilobase (kb):

Unit of length for DNA fragments equal to 1000 nucleotides.

Kinase:

A kinase is in general an enzyme that catalyzes the transfer of a phosphate group from ATP to something else. In molecular biology, it has acquired the more specific verbal usage for the transfer onto DNA of a radiolabeled phosphate group.

Kinetic Complexity:

It is the complexity of a DNA compound measured by the kinetics of DNA reassociation.

Kinteochore:

A specialized structure found in the centromeric region of the chromosome that is responsible for attaching to the spindle during nuclear division.

Klenow Fragment:

The large fragment of E. coli DNA polymerase I which lacks 5' -> 3' exonuclease activity.

Knock-Out Experiment:

A technique for deleting, mutating or otherwise inactivating a gene in a mouse.