Polyploidy

Having three or more chromosomes in the nucleus of eukariotic cells at interphase.

Mosaicism

Cells of same type express genes differently, so phenotypic differences emerge in same type of tissue. E.g., occurs by X chromosome inactivation in female mammals; also by nondisjunction in any cell after fertilization (only descendants of altered cell inherit the abnormal chromosome number).

Linkage Group

A linkage group are all the genes in a chromosomes.