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(extrachromosomal inheritance) The determination of a characteristic by genes in the cytoplasm (plasmagenes) rather than in the chromosomes. The expression of a cyto-plasmically determined character is therefore not related to the behaviour or movement of chromosomes, and consequently such characters fail to segregate in Mendelian ratios. They are normally transmitted through the female gamete, which contributes most of the cytoplasm to the zygote, the male gametes only contributing a nucleus. Genes inherited in this manner are found on DNA present in small quantities in the chloroplasts, mitochondria, and sometimes the cytosol itself. An example of a characteristic inherited in this fashion is a form of male sterility in maize (Zea mays).
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