Mitochondrial genes are inherited exclusively from which parent?

Mitochondrial genes are inherited exclusively from the mother due to the unique way in which mitochondria are passed down during reproduction. When an egg and sperm unite to form a zygote, the sperm contributes nuclear DNA but does not typically contribute its mitochondria to the embryo. Instead, the embryo inherits its mitochondria, along with the associated mitochondrial DNA (mtDNA), from the egg cell, which contains the mitochondria.

This maternal inheritance pattern can be linked to the origin of mitochondria, which are thought to have evolved from free-living prokaryotic organisms that eventually entered into a symbiotic relationship with ancestral eukaryotic cells. As a result, only mtDNA from the maternal lineage is passed on to offspring, leading to a situation where all descendants of a mother will share the same mitochondrial genetic material.

In contrast, nuclear DNA contributes genetic information from both the mother and the father, but mitochondria remain maternal in origin. Understanding this inheritance pattern is essential in fields such as genetics, medicine, and evolutionary biology, as it helps trace maternal lineages and can have implications for certain genetic diseases that are linked to mitochondrial dysfunction.