Glossary Plant Breeding

Karyogamy. The fusion of nuclei of male and female gametes. It is the ultimate event
(culmination) of fertilization. The result of the karyogamy is the zygote.
Karyokinesis. The division of nucleus; the nuclear division (mitosis).
Karyolymph. The karyoplasm; nucleoplsm.
Karyotype. The whole group of characteristics that allow identification of a particular
chromosome set, for example, the number, relative size, position of centromere,
length of the arms, secondary constrictions, satellite, and the like. It is characteristic
of an individual, species, genera, or a larger group.
Kilobase. 1000 nucleotide pairs.
Kinetochore. A complex of proteins to which a nuclear spindle fibre attaches. Cell
biologists use the term more frequently instead of centromere, which is synonymous
to kinetochore.
Klinefelter Syndrome. An abnormal human male phenotype due to an extra X
chromosome (XXY).
Knobs. The darkly stained heterochromatic regions present in normal maize
chromosomes. These are repeated sequences of nucleotides. The number of knobs
varies from variety to variety, and from plant to plant. Some have reported that their
standard number may be 23. They are not randomly distributed; rather they occupy
fixed positions on different chromosomes. Most of the knobs are intercalary.
Terminal knobs are rare. They have been used as markers to establish phylogenetic
relationship between maize and its wild relatives.
Knockout. Inactivation of one specific gene; same as gene disruption.
Krebs Cycle. A common pathway for degradation of “fuel” molecules such as
carbohydrates, fatty acids, and amino acids. Also called tricaboxylic acid cycle or
citric acid cycle, it takes place in mitochondrial matrix. The fuel molecules are acted
upon metabolically (in the cytoplasm through the process of glycolysis) to produce
acetyl groups, which are taken into the Krebs cycle by acetyl coenzyme. It takes two
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