1 a mutation occurring in a somatic cell, resulting in a change in the morphology or some other aspect of one part of an organism (usually a plant). 2  It may be maintained by vegetative propagation but not by sexual reproduction.oun. 1  a mutation occurring in a somatic cell, resulting in a change in the morphology or some other aspect of one part of an organism (usually a plant). 2  It may be maintained by vegetative propagation but not by sexual reproduction.
Although oxidation reactions are commonly associated with the formation of oxides from oxygen molecules, oxygen is not necessarily included in such reactions, as other chemical species can serve the same function. The reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire.
Enzymes have extremely interesting properties that make them little chemical-reaction machines. The purpose of an enzyme in a cell is to allow the cell to carry out chemical reactions very quickly. These reactions allow the cell to build things or take things apart as needed.