<P> However, mitochondrial DNA reflects only the history of the females in a population and so may not represent the history of the population as a whole . This can be partially overcome by the use of paternal genetic sequences, such as the non-recombining region of the Y - chromosome . In a broader sense, only studies that also include nuclear DNA can provide a comprehensive evolutionary history of a population . </P> <P> Recent measurements of the molecular clock for mitochondrial DNA reported a value of 1 mutation every 7884 years dating back to the most recent common ancestor of humans and apes, which is consistent with estimates of mutation rates of autosomal DNA (10 per base per generation). </P> <P> Damage and subsequent dysfunction in mitochondria is an important factor in a range of human diseases due to their influence in cell metabolism . Mitochondrial disorders often present themselves as neurological disorders, including autism . They can also manifest as myopathy, diabetes, multiple endocrinopathy, and a variety of other systemic disorders . Diseases caused by mutation in the mtDNA include Kearns - Sayre syndrome, MELAS syndrome and Leber's hereditary optic neuropathy . In the vast majority of cases, these diseases are transmitted by a female to her children, as the zygote derives its mitochondria and hence its mtDNA from the ovum . Diseases such as Kearns - Sayre syndrome, Pearson syndrome, and progressive external ophthalmoplegia are thought to be due to large - scale mtDNA rearrangements, whereas other diseases such as MELAS syndrome, Leber's hereditary optic neuropathy, myoclonic epilepsy with ragged red fibers (MERRF), and others are due to point mutations in mtDNA . </P> <P> In other diseases, defects in nuclear genes lead to dysfunction of mitochondrial proteins . This is the case in Friedreich's ataxia, hereditary spastic paraplegia, and Wilson's disease . These diseases are inherited in a dominance relationship, as applies to most other genetic diseases . A variety of disorders can be caused by nuclear mutations of oxidative phosphorylation enzymes, such as coenzyme Q10 deficiency and Barth syndrome . Environmental influences may interact with hereditary predispositions and cause mitochondrial disease . For example, there may be a link between pesticide exposure and the later onset of Parkinson's disease . Other pathologies with etiology involving mitochondrial dysfunction include schizophrenia, bipolar disorder, dementia, Alzheimer's disease, Parkinson's disease, epilepsy, stroke, cardiovascular disease, chronic fatigue syndrome, retinitis pigmentosa, and diabetes mellitus . </P>

Where is the mitochondria located in a plant cell