Extranuclear inheritance

Extranuclear inheritance is the transmission of traits through genetic material outside the cell nucleus, usually DNA in mitochondria or chloroplasts. Its inheritance patterns often differ from those of nuclear genes.

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Mitochondrial DNA: The DNA molecule or molecules carried by mitochondria, encoding some proteins and RNAs needed for mitochondrial function. Mitochondrial genes are a major source of traits transmitted outside the nucleus.
Mirabilis jalapa leaf variegation: A pattern of green, white, and variegated leaves in four-o'clock plants, associated with plastid inheritance. The offspring’s leaf color follows the seed parent’s cytoplasm rather than ordinary nuclear inheritance.
Mendelian inheritance: The transmission of nuclear alleles through predictable segregation patterns described by Gregor Mendel. Extranuclear traits can depart from Mendelian ratios because organelles segregate separately.
Mitochondrial replacement therapy: Assisted reproductive techniques that place parents’ nuclear DNA into an egg or embryo with donor mitochondria. The techniques aim to reduce transmission of harmful mitochondrial DNA variants.
Eukaryotic cell: A cell whose DNA is enclosed in a nucleus and whose internal structures include membrane-bound organelles. Extranuclear inheritance depends on genetic material residing in organelles beyond the nucleus.
Chloroplast DNA: The DNA carried by chloroplasts, encoding some components of photosynthesis and chloroplast gene expression. Chloroplast genes transmit traits such as leaf pigmentation through organelles.
Petite mutants: Respiration-deficient yeast mutants that form small colonies because of defects in mitochondrial function or DNA. Their inheritance exposed mitochondrial contributions to traits in a classic genetic model.
Genomic imprinting: Parent-of-origin-dependent gene expression caused by epigenetic marks on nuclear DNA. It can resemble parent-specific organelle inheritance, but the genes remain nuclear.
Mitochondrial Eve: The most recent woman from whom all living humans inherit their mitochondrial DNA through an unbroken maternal line. Her concept relies on the maternal transmission of mitochondrial genomes.
Mitochondrion: A membrane-bound organelle that produces much of a eukaryotic cell’s usable energy through cellular respiration. Mitochondria carry genomes that can pass independently of nuclear chromosomes.