Mitochondrial genes are carried by a molecule of circular DNA of 16569b, inhereted by the mother Mitochondrial DNA, because the mitochondria of sperm are destroyed by the egg cell after fertilization. After the penetration of the sperm , the egg cell keeps the nuclear contain,and all the rest will be destroyed by enzyms, so by this mechanism, the mitochondria still just the mother’s one, plus to this, the mitochondria of the sperm is presented in its tail for proplling the cell. This mitochondrial DNA is transmissed to all of the mother’s descendants boys and girls, but this transmission stops at each boy, so if there is any mutation to this DNA, all the girls inherit it to their descendants. The mitochondrial DNA contain a lot of genes such as :NADH dehydrogenase, ATP synthase. The most known desease by mitochondrial DNA is leber’s Hereditary optic Atrophy wich is a brutal loss of vision and quickly for teenagers and young adults.