Uniparental inheritance
Encyclopedia
Uniparental inheritance is a non-mendelian form of inheritance that consists of the transmission of genotypes from one parental type to all progeny. That is, all the genes in offspring will originate from only the mother or only the father. This phenomenon is most commonly observed in eukaryotic organelles such as mitochondria and chloroplast
s. This is because such organelles contain their own DNA and are capable of independent mitotic replication that does not endure crossing over with the DNA from another parental type. Although uniparental inheritance is the most common form of inheritance in organelles, there is increased evidence of diversity. Some studies found doubly uniparental inheritance (DUI) and biparental transmission to exist in cells. Evidence suggests that even when there is biparental inheritance, crossing-over doesn't always occur. Furthermore, there is evidence that the form of organelle inheritance varied frequently over time. Uniparental inheritance can be divided into multiple subtypes based on the pathway of inheritance.
or are capable of replication independent of the nucleus, there are some exceptions such as mitochondria and chloroplasts. Not only are these organelles capable of independent DNA replication, translation, and transcription, they are commonly known to inherit genes from only one parental type. In the case of mitochondria, maternal inheritance is almost the exclusive form of inheritance. Although, during egg cell fertilization, mitochondria are brought into the fertilized cell both by the egg cell and the sperm, the paternal mitochondria are usually marked with ubiquitin
and are later destroyed. Even if they are not destroyed, the DNA's of different mitochondria rarely genetically recombine
with one another. Thus, mitochondria in most animals are inherited from the maternal type only.
Like all other genetic concepts, the discovery of uniparental inheritance stems from the days of an Augustinian priest known as Gregor Johann Mendel. The soon-to-be "father of modern genetics" spent his days conducing hybridization experiments
on pea plants(Pisum sativum) in his monastery's garden. During a period of seven years (1856 to 1863), Mendel cultivated and tested some 29,000 pea plants which lead to him deducing the two famous generalizations known as Mendel's Laws of Heredity
. The first, the law of segregation, states that "when any individual produces gamete
s, the copies of a gene separate, so that each gamete receives only one copy". The second, the law of independent assortment, states that "allele
s of different genes assort independently of one another during gamete formation". Although his work was published, it lay dormant until it was rediscovered in 1900 by Hugo de Vries
and Carl Correns
but it was not until 1909 that non-mendelian inheritance was even suggested. Carl Erich Correns and Erwin Baur
, in separately conducted researches on Pelargonium
and Mirabilis
plants, observed a green-white variation (later found as the result of mutation
s in the chloroplast
genome) that did not follow the Mendelian laws of inheritance. Nearly twenty years later, non-mendelian inheritance of a mitochondrial mutation was also observed and, in the sixties, it was proven that that chloroplasts and mitochondria have their own DNA
and that they are capable translation, transcription, and replication independent of the nucleus. Soon after, the discoveries of uniparental and doubly uniparental inheritance came.
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
s. This is because such organelles contain their own DNA and are capable of independent mitotic replication that does not endure crossing over with the DNA from another parental type. Although uniparental inheritance is the most common form of inheritance in organelles, there is increased evidence of diversity. Some studies found doubly uniparental inheritance (DUI) and biparental transmission to exist in cells. Evidence suggests that even when there is biparental inheritance, crossing-over doesn't always occur. Furthermore, there is evidence that the form of organelle inheritance varied frequently over time. Uniparental inheritance can be divided into multiple subtypes based on the pathway of inheritance.
Organelles
Although most of the eukaryotic sub-cellular parts do not have their own DNADNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
or are capable of replication independent of the nucleus, there are some exceptions such as mitochondria and chloroplasts. Not only are these organelles capable of independent DNA replication, translation, and transcription, they are commonly known to inherit genes from only one parental type. In the case of mitochondria, maternal inheritance is almost the exclusive form of inheritance. Although, during egg cell fertilization, mitochondria are brought into the fertilized cell both by the egg cell and the sperm, the paternal mitochondria are usually marked with ubiquitin
Ubiquitin
Ubiquitin is a small regulatory protein that has been found in almost all tissues of eukaryotic organisms. Among other functions, it directs protein recycling.Ubiquitin can be attached to proteins and label them for destruction...
and are later destroyed. Even if they are not destroyed, the DNA's of different mitochondria rarely genetically recombine
Genetic recombination
Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method...
with one another. Thus, mitochondria in most animals are inherited from the maternal type only.
History
Like all other genetic concepts, the discovery of uniparental inheritance stems from the days of an Augustinian priest known as Gregor Johann Mendel. The soon-to-be "father of modern genetics" spent his days conducing hybridization experiments
Experiments on Plant Hybridization
Written in 1865 by Gregor Mendel, Experiments on Plant Hybridization was the result after years spent studying genetic traits in pea plants. Mendel read his paper to the Natural History Society of Brünn on February 8 and March 8, 1865...
on pea plants(Pisum sativum) in his monastery's garden. During a period of seven years (1856 to 1863), Mendel cultivated and tested some 29,000 pea plants which lead to him deducing the two famous generalizations known as Mendel's Laws of Heredity
Mendelian inheritance
Mendelian inheritance is a scientific description of how hereditary characteristics are passed from parent organisms to their offspring; it underlies much of genetics...
. The first, the law of segregation, states that "when any individual produces gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s, the copies of a gene separate, so that each gamete receives only one copy". The second, the law of independent assortment, states that "allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s of different genes assort independently of one another during gamete formation". Although his work was published, it lay dormant until it was rediscovered in 1900 by Hugo de Vries
Hugo de Vries
Hugo Marie de Vries ForMemRS was a Dutch botanist and one of the first geneticists. He is known chiefly for suggesting the concept of genes, rediscovering the laws of heredity in the 1890s while unaware of Gregor Mendel's work, for introducing the term "mutation", and for developing a mutation...
and Carl Correns
Carl Correns
Carl Erich Correns was a German botanist and geneticist, who is notable primarily for his independent discovery of the principles of heredity, and for his rediscovery of Gregor Mendel's earlier paper on that subject, which he achieved simultaneously but independently of the botanists Erich...
but it was not until 1909 that non-mendelian inheritance was even suggested. Carl Erich Correns and Erwin Baur
Erwin Baur
Erwin Baur was a German geneticist and botanist. Baur worked primarily on plant genetics. He was director of the Kaiser Wilhelm Institute for Breeding Research . Baur is considered to be the father of plant virology...
, in separately conducted researches on Pelargonium
Pelargonium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...
and Mirabilis
Mirabilis (plant)
Mirabilis is a genus of plants in the family Nyctaginaceae known as the four o'clocks. The best known species may be Mirabilis jalapa, the plant most commonly called four o'clock....
plants, observed a green-white variation (later found as the result of mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s in the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
genome) that did not follow the Mendelian laws of inheritance. Nearly twenty years later, non-mendelian inheritance of a mitochondrial mutation was also observed and, in the sixties, it was proven that that chloroplasts and mitochondria have their own DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
and that they are capable translation, transcription, and replication independent of the nucleus. Soon after, the discoveries of uniparental and doubly uniparental inheritance came.
See also
- Non-Mendelian inheritanceNon-mendelian inheritanceNon-Mendelian inheritance is a general term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws. These laws describe the inheritance of traits linked to single genes on chromosomes in the nucleus. In Mendelian inheritance, each parent...
- Extranuclear inheritanceExtranuclear InheritanceExtranuclear inheritance is the transmission of genes that occur outside the nucleus. It is found in most eukaryotes and is commonly known to occur in cytoplasmic organelles such as mitochondria and chloroplasts or from cellular parasites like viruses or bacteria .- Extranuclear Inheritance of...
- Gregor Johann Mendel
- Mendelian inheritanceMendelian inheritanceMendelian inheritance is a scientific description of how hereditary characteristics are passed from parent organisms to their offspring; it underlies much of genetics...
- Epigenetic inheritance
- Organelles