Dr. Paul's Virtually Biology Show.

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K

Karyotype. A picture of the chromosomes of a cell showing the chromosomes in order by size and shape to facilitate chromosome identification.
Keratin. A fibrous protein found in hair, horns, hooves, feathers, scales and nails of of various vertebrates.
Kinase. An enzyme that catalyzes the transfer of a phosphate group from ATP to another substrate.

Kinesis. A Kinesis is an undirected change in movement in response to an environmental stimulus. Unlike a taxis, a kinesis is not oriented toward or away from the stimulus.

Kinetochore. A region of specialized proteins at the centromere that serves as an attachment point for spindle microtubules during mitosis and meiosis.

Kin selection. A Kin selection is a kind of natural selection in which individuals increase the number of their genes left to future generations by providing aid to relatives who also share some of the same genes.

Kreb's cycle(Citric acid cycle). A series of chemical reactions that takes a two carbon residue from acetyl CoA and strips high energy electrons and hydrogen ions(protons) from the residue. These electrons and protons are used to make ATP and the starting material for the cycle is regenerated to pick up more two carbon residues. The term citric acid cycle refers to the fact that citric acid results when the two carbon residue attaches to the cycle's starting material.