Extranuclear Inheritance. • Organelle heredity. – Organelles that contain chromosomes. • Chloroplasts and mitochondria. • Infectious heredity. – Involves a . Extranuclear inheritance or cytoplasmic inheritance is the transmission of genes that occur . Print/export. Create a book · Download as PDF · Printable version. Cytoplasmic inheritance??? Extranuclear inheritance or cytoplasmic inheritance is the transmission of genes that occur outside the nucleus.
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Mitochondria and chloroplasts. ® „ These organelles are found in the cytoplasm. ® „ Therefore, extranuclear inheritance is also termed cytoplasmic inheritance. The past couple of lectures, we've been exploring exceptions to Mendel's principles of transmission inheritance. Scientists have observed inheritance patterns. Extranuclear Inheritance. Maternal Effects. • Phenotype of Offspring is determined (at least in part) by mother's nuclear genotype. • Examples.
The number of individuals who carry a mutation is less than the number of individuals who have an abnormal phenotype. This is a quantitative estimate. An improved method to evaluate mutations in those families will allow us to better understand this notion of penetrance. C not to confound an isolate case due to a reduced penetrance with a sporadic case due to a mutation. This a variable expressivity of the deleterious gene. It is a qualitative evaluation. In Marfan syndrome for an identical familial gene mutation, some individuals will have a severe form of the disease affecting the cardio-vascular, ocular and skeletal systems while for other individuals only the tall stature and arachnodactyly, without lens dislocation or aortic aneurysm, will be noted.
For some individuals rickets is due to a vitamin D deficiency that will be corrected by the addition of a vitamin supplement in the diet. For others the disease due to the absence of the active form of Vitamin D, an autosomal recessive disease, or several other mutations regulating the vitamin D metabolism. Mutations of cancer suppressors, protein regulators enzymes or DNA repair genes have been identified.
For example those mutations can induce metabolic diseases like mucopolysaccharidoses, ovary and colon cancers and DNA repair defects like Ataxia telangiectasia.
If a deletion occurs in gene WT1 located on chromosome 11 in region 11p13, it will lead to a Wilms tumor and a nephropathy. Syndrome WAGR W:: Wilms; A: aniridia, G: genito-urinary malformations, R: mental retardation would result from the deletion of this and other contiguous genes located in region 11pp Another example is Beckwith-Wiedemann syndrome also located on chromosome 11, in region 11p The syndrome manifests with obesity, macroglossia, nephroblastoma hepatoblastoma, neuroblastoma gigantism and omphalocele.
Doubt may arise about the paternity of an individual if ongoing molecular studies do not find in the suspected father the presence of one or more DNA sequences. Several groups of diseases like glycogenoses and mucopolysaccharidoses often have a similar phenotype but a different enzymatic deficiency confirmed by the identification of a specific mutation for each one of them.
Annu Rev Genet.
Recombination between the extranuclear genes conferring oligomycin resistance and cold sensitivity in Aspergillus nidulans. Mol Gen Genet. A genetic system controlling mitochondrial fusion in the slime mould, Physarum polycephalum. Recombination between chloroplast DNAs does not occur in sexual crosses of Oenothera. Interspecific chloroplast recombination in a Nicotiana somatic hybrid.
Evolutionary relationships among the male and female mitochondrial DNA lineages in the Mytilus edulis species complex. Mol Biol Evol.
Male and female mitochondrial DNA lineages in the blue mussel Mytilus edulis species group. Spermiogenesis in the crayfish Procambarus clarkii II. Description of stages. J Biophys Biochem Cytol.
Selective silencing of eukaryotic DNA. Fate of sperm tail components after incorporation into the hamster egg. Gamete Res.
Elimination of paternal mitochondrial DNA in intraspecific crosses during early mouse embryogenesis. The fate of sperm middle-piece mitochondria in the rat egg.
J Exp Zool. Curr Genet. Nuclear and extranuclear inheritance of oligomycin resistance in Aspergillus nidulans. Parasites[ edit ] Extranuclear transmission of viral genomes and symbiotic bacteria is also possible.
An example of viral genome transmission is perinatal transmission. This occurs from mother to fetus during the perinatal period, which begins before birth and ends about 1 month after birth.
During this time viral material may be passed from mother to child in the bloodstream or breastmilk. Vegetative segregation results from random replication and partitioning of cytoplasmic organelles.
It occurs with chloroplasts and mitochondria during mitotic cell divisions and results in daughter cells that contain a random sample of the parent cell's organelles. An example of vegetative segregation is with mitochondria of asexually replicating yeast cells.
A classic example of uniparental gene transmission is the maternal inheritance of human mitochondria. The mother's mitochondria are transmitted to the offspring at fertilization via the egg.