Final answer:
Mitochondria, including their DNA, are inherited from the mother, and because mitochondrial DNA (mtDNA) does not undergo recombination and is more rapidly mutating than nuclear DNA, it is a valuable tool for understanding genealogy and evolutionary biology.
Step-by-step explanation:
How Mitochondria Are Inherited in Humans
In humans and most mammals, mitochondria are inherited maternally, meaning that offspring receive their mitochondria from their mother. This is because the mitochondria are located in the cytoplasm of the egg cell rather than in the sperm. As a result, when fertilization occurs, the mitochondria from the sperm are typically not passed on to the offspring. Instead, all of the mitochondria present in the zygote come from the mother's egg. This matrilineal inheritance is particularly valuable in the study of genealogy and evolutionary biology because mitochondrial DNA (mtDNA) mutates more rapidly than nuclear DNA.
Each human cell contains multiple mitochondria, approximately 1700, with each one packed with mtDNA encoding for about 37 genes. These genes primarily relate to the electron transport chain, which is critical for cellular energy production. Since there is no recombination of mtDNA, barring mutations, the mtDNA remains consistent from mother to offspring. The study of mtDNA is so informative that it has been used to trace the lineage back to a common ancestor often referred to as 'Mitochondrial Eve'.