biology-dictionary_11-06-2009

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Codon
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or
termination signal; the basic unit of the genetic code.
Coelom
A body cavity completely lined with mesoderm.
Coelomate
An animal whose body cavity is completely lined by mesoderm, the layers of which connect
dorsally and ventrally to form mesenteries.
Coenocytic
Referring to a multinucleated condition resulting from the repeated division of nuclei
without cytoplasmic division.
Coenzyme
An organic molecule serving as a cofactor. Most vitamins function as coenzymes in
important metabolic reactions.
Coevolution
The mutual influence on the evolution of two different species interacting with each other
and reciprocally influencing each other's adaptations.
Cofactor
Any nonprotein molecule or ion that is required for the proper functioning of an enzyme.
Cofactors can be permanently bound to the active site or may bind loosely with the
substrate during catalysis.
Cohesion
The binding together of like molecules, often by hydrogen bonds.
Cohesion species concept
The idea that specific evolutionary adaptations and discrete complexes of genes define
species.
Cohesion-tension theory
A theory accounting for the upward movement of water in plants. According to this theory,
transpiration of a water molecule results in a negative (below 1 atmosphere) pressure in the
leaf cells, inducing the entrance from the vascular tissue of another water molecule, which,
because of the cohesive property of water, pulls with it a chain of water molecules
extending up from the cells of the root tip.

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