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Y-mrca
In human genetics, the Y-chromosomal most recent common ancestor (Y-MRCA, informally known as Y-chromosomal Adam) is the patrilineal most recent common ancestor (MRCA) from whom all currently living humans are descended. He is the most recent male from whom all living humans are descended through an unbroken line of their male ancestors. The term Y-MRCA reflects the fact that the Y chromosomes of all currently living human males are directly derived from the Y chromosome of this remote ancestor. The analogous concept of the matrilineal most recent common ancestor is known as " Mitochondrial Eve" (mt-MRCA, named for the matrilineal transmission of mtDNA), the most recent woman from whom all living humans are descended matrilineally. As with "Mitochondrial Eve", the title of "Y-chromosomal Adam" is not permanently fixed to a single individual, but can advance over the course of human history as paternal lineages become extinct. Estimates of the time when Y-MRCA lived have also s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplogroup A00
Haplogroup A is a human Y-chromosome DNA haplogroup, which includes all living human Y chromosomes. Bearers of extant sub-clades of haplogroup A are almost exclusively found in Africa (or among descendants of populations which have recently left Africa), in contrast with haplogroup BT, bearers of which participated in the Out of Africa migration of anatomically modern humans. The known branches of haplogroup A are A00, A0, A1a, and A1b1; these branches are only very distantly related, and are not more closely related to each other than they are to haplogroup BT. Origin There are terminological difficulties, but as "haplogroup A" has come to mean "the foundational haplogroup" (viz. of contemporary human population), haplogroup A is not defined by any mutation but refers to any haplogroup which is not descended from the haplogroup BT, i.e. defined by the absence of the defining mutation of that group (M91). By this definition, haplogroup A includes all mutations that took plac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrial Eve
In human genetics, the Mitochondrial Eve (also ''mt-Eve, mt-MRCA'') is the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman. In terms of mitochondrial haplogroups, the mt-MRCA is situated at the divergence of macro-haplogroup L into L0 and L1–6. As of 2013, estimates on the age of this split ranged at around 155,000 years ago, consistent with a date later than the speciation of ''Homo sapiens'' but earlier than the recent out-of-Africa dispersal. The male analog to the "Mitochondrial Eve" is the "Y-chromosomal Adam" (or Y-MRCA), the individual from whom all living humans are patrilineally descended. As the identity of both matrilineal and patrilineal MRCAs is dependent on genealogical history ( pedigree collapse), they need not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mt-MRCA
In human genetics, the Mitochondrial Eve (also ''mt-Eve, mt-MRCA'') is the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman. In terms of mitochondrial haplogroups, the mt-MRCA is situated at the divergence of macro-haplogroup L into L0 and L1–6. As of 2013, estimates on the age of this split ranged at around 155,000 years ago, consistent with a date later than the speciation of ''Homo sapiens'' but earlier than the recent out-of-Africa dispersal. The male analog to the "Mitochondrial Eve" is the "Y-chromosomal Adam" (or Y-MRCA), the individual from whom all living humans are patrilineally descended. As the identity of both matrilineal and patrilineal MRCAs is dependent on genealogical history (pedigree collapse), they need not ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Most Recent Common Ancestor
In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The term is also used in reference to the ancestry of groups of genes ( haplotypes) rather than organisms. The MRCA of a set of individuals can sometimes be determined by referring to an established pedigree. However, in general, it is impossible to identify the exact MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such ''time to most recent common ancestor'' (''TMRCA'') estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non-genetic, mathematical model or computer simulation. In organisms using sexual reproduction, the ''matrilineal MRCA'' and ''patrilineal MRCA'' are the MRCAs of a given populati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patrilineality
Patrilineality, also known as the male line, the spear side or agnatic kinship, is a common kinship system in which an individual's family membership derives from and is recorded through their father's lineage. It generally involves the inheritance of property, rights, names, or titles by persons related through male kin. This is sometimes distinguished from cognate kinship, through the mother's lineage, also called the spindle side or the distaff side. A patriline ("father line") is a person's father, and additional ancestors, as traced only through males. Traditionally and historically people would identify the person's ethnicity with the father's heritage and ignore the maternal ancestry in the ethnic factor. In the Bible In the Bible, family and tribal membership appears to be transmitted through the father. For example, a person is considered to be a priest or Levite, if his father is a priest or Levite, and the members of all the Twelve Tribes are called Israelites because ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Y-chromosome DNA Haplogroup
In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by mutations in the non- recombining portions of DNA from the male-specific Y chromosome (called Y-DNA). Many people within a haplogroup share similar numbers of short tandem repeats (STRs) and types of mutations called single-nucleotide polymorphisms (SNPs). The human Y-chromosome accumulates roughly two mutations per generation. "one mutation in every 30 million base pairs" Y-DNA haplogroups represent major branches of the Y-chromosome phylogenetic tree that share hundreds or even thousands of mutations unique to each haplogroup. The Y-chromosomal most recent common ancestor (Y-MRCA, informally known as Y-chromosomal Adam) is the most recent common ancestor (MRCA) from whom all currently living humans are descended patrilineally. Y-chromosomal Adam is estimated to have lived roughly 236,000 years ago in Africa. By examining other bottlenecks most Eurasian men (men from populations outsid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y-chromosomal Haplogroup
In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by mutations in the non- recombining portions of DNA from the male-specific Y chromosome (called Y-DNA). Many people within a haplogroup share similar numbers of short tandem repeats (STRs) and types of mutations called single-nucleotide polymorphisms (SNPs). The human Y-chromosome accumulates roughly two mutations per generation. "one mutation in every 30 million base pairs" Y-DNA haplogroups represent major branches of the Y-chromosome phylogenetic tree that share hundreds or even thousands of mutations unique to each haplogroup. The Y-chromosomal most recent common ancestor (Y-MRCA, informally known as Y-chromosomal Adam) is the most recent common ancestor (MRCA) from whom all currently living humans are descended patrilineally. Y-chromosomal Adam is estimated to have lived roughly 236,000 years ago in Africa. By examining other bottlenecks most Eurasian men (men from populations outside of Af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosomes
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA. For example, humans have a diploid genome that usually contains 22 pairs of autosomes and one allosome pair (46 chromosomes total). The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labelled with their letters. By contrast, the allosome pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations of XYY, XXY, XXX, XXXX, XXXXX or XXYY, among other Salome combinations, are known to occur and usually cause developmental abnormalities. Autosomes still contain sexual determination genes even though they are not sex chromosomes. For example, the SRY gene on the Y chromosom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the cell nucleus and, in plants and algae, also in plastids such as chloroplasts. Human mitochondrial DNA was the first significant part of the human genome to be sequenced. This sequencing revealed that the human mtDNA includes 16,569 base pairs and encodes 13 proteins. Since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology. It also permits an examination of the relatedness of populations, and so has become important in anthropology and biogeography. Origin Nuclear and mitochondrial DNA are thought to be of separate evolutionary origin, with the mtDNA being deri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Pair
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson–Crick–Franklin") base pairs ( guanine– cytosine and adenine– thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The complementary nature of this based-paired structure provides a redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and RNA polymerase transcribes DNA into RNA. Many DNA-binding p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Evolution
Molecular evolution is the process of change in the sequence composition of cell (biology), cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics to explain patterns in these changes. Major topics in molecular evolution concern the rates and impacts of single nucleotide changes, Neutral theory of molecular evolution, neutral evolution vs. natural selection, origins of new genes, the genetic nature of complex traits, the genetic basis of speciation, evolution of development, and ways that evolutionary forces influence genome, genomic and phenotype, phenotypic changes. History The history of molecular evolution starts in the early 20th century with comparative biochemistry, and the use of "fingerprinting" methods such as immune assays, gel electrophoresis and paper chromatography in the 1950s to explore homologous proteins. The field of molecular evolution came into i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately result in four cells with only one copy of each chromosome ( haploid). Additionally, prior to the division, genetic material from the paternal and maternal copies of each chromosome is crossed over, creating new combinations of code on each chromosome. Later on, during fertilisation, the haploid cells produced by meiosis from a male and female will fuse to create a cell with two copies of each chromosome again, the zygote. Errors in meiosis resulting in aneuploidy (an abnormal number of chromosomes) are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells, each with half the number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
