Extranuclear inheritance

It is found in most eukaryotes and is commonly known to occur in cytoplasmic organelles such as mitochondria and chloroplasts or from cellular parasites like viruses or bacteria.

In many cases of fertilization, the head of the sperm enters the egg cell; leaving its middle part, with its mitochondria, behind.

During this time viral material may be passed from mother to child in the bloodstream or breastmilk.

Poky is characterized by slow growth, a defect in mitochondrial ribosome assembly and deficiencies in several cytochromes.

[10] The studies of poky mutants were among the first to establish an extranuclear mitochondrial basis for inheritance of a particular genotype.