Mitochondrial dNA:
Mitochondria are the organelles that produce a majority of the cell's energy required for metabolic activities, as it is the site of aerobic respiration. Although a vast majority of an organism's DNA is contained in the nucleus of its cells, some may also exist in the mitochondria; this is referred to as mitochondrial DNA or mtDNA. Like nuclear DNA, it is made up of genes and is a double-stranded structure. However, unlike normal DNA, mitochondrial DNA contains 37 genes, which are all necessary for the normal operation of mitochondria. Of these 37 genes, 24 of them contain the code for making RNA molecules, while the other 13 contain some of the instructions necessary for protein synthesis. The genes are also arranged in a circular pattern instead of the regular double-helix structure.
Rare genetic disorders such as dysphagia, cardiomyopathy and ptosis occur from mutations in mitochondrial DNA. However, unlike normal mutations, which could potentially be inherited from both parents, mitochondrial mutations can only be inherited from the mother. This is because that although both sperm and egg contain mitochondria, after the sperm penetrates the egg, its mitochondria are rapidly destroyed. Thus, only the mother's mitochondria are left, which are all the child can inherit.
Rare genetic disorders such as dysphagia, cardiomyopathy and ptosis occur from mutations in mitochondrial DNA. However, unlike normal mutations, which could potentially be inherited from both parents, mitochondrial mutations can only be inherited from the mother. This is because that although both sperm and egg contain mitochondria, after the sperm penetrates the egg, its mitochondria are rapidly destroyed. Thus, only the mother's mitochondria are left, which are all the child can inherit.