Meiosis is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each 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 a female will fuse to create a zygote, a cell with two copies of each chromosome again.
Mendelian inheritance is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularized by William Bateson. These principles were initially controversial. When Mendel's theories were integrated with the Boveri–Sutton chromosome theory of inheritance by Thomas Hunt Morgan in 1915, they became the core of classical genetics. Ronald Fisher combined these ideas with the theory of natural selection in his 1930 book The Genetical Theory of Natural Selection, putting evolution onto a mathematical footing and forming the basis for population genetics within the modern evolutionary synthesis.
Racial segregation is the separation of people into racial or other ethnic groups in daily life. Segregation can involve the spatial separation of the races, and mandatory use of different institutions, such as schools and hospitals by people of different races. Specifically, it may be applied to activities such as eating in restaurants, drinking from water fountains, using public toilets, attending schools, going to films, riding buses, renting or purchasing homes or renting hotel rooms. In addition, segregation often allows close contact between members of different racial or ethnic groups in hierarchical situations, such as allowing a person of one race to work as a servant for a member of another race. Racial segregation has generally been outlawed worldwide.
A pair of homologous chromosomes, or homologs, is a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same loci, where they provide points along each chromosome that enable a pair of chromosomes to align correctly with each other before separating during meiosis. This is the basis for Mendelian inheritance, which characterizes inheritance patterns of genetic material from an organism to its offspring parent developmental cell at the given time and area.
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division (mitosis/meiosis). There are three forms of nondisjunction: failure of a pair of homologous chromosomes to separate in meiosis I, failure of sister chromatids to separate during meiosis II, and failure of sister chromatids to separate during mitosis. Nondisjunction results in daughter cells with abnormal chromosome numbers (aneuploidy).
Sex segregation, sex separation, sex partition,gender segregation,gender separation, or gender partition is the physical, legal, or cultural separation of people according to their biological sex at any age. Sex segregation can refer simply to the physical and spatial separation by sex without any connotation of illegal discrimination. In other circumstances, sex segregation can be controversial. Depending on the circumstances, it can be a violation of capabilities and human rights and can create economic inefficiencies; on the other hand, some supporters argue that it is central to certain religious laws and social and cultural histories and traditions.
Racial separatism may refer to:
Separation of duties (SoD), also known as segregation of duties, is the concept of having more than one person required to complete a task. It is an administrative control used by organisations to prevent fraud, sabotage, theft, misuse of information, and other security compromises. In the political realm, it is known as the separation of powers, as can be seen in democracies where the government is separated into three independent branches: a legislature, an executive, and a judiciary.
Polarization or polarisation may refer to:
Community of interest is a means in which network assets and or network users are segregated by some technological means for some established purpose. COIs are a strategy that fall under the realm of computer security which itself is a subset of security engineering. Typically, COIs are set up to protect a network infrastructure from a group or groups of users who are performing some esoteric functions. COIs are also designed to protect their user community from the rest of the enclave user population. Not only does this refer to the simplicity of the network, but it also includes a group of people that come together on different social networks to share data. There are multiple examples such as Wikipedia, Facebook, Blogs, YouTube, and many more where people come together as a community of interest to work together towards a common goal, learn from each other, critique, and share ideas. These users and group of people are separated into categories and segregated into logical groups. There can be professional groups, health groups that include people interested in specific diets, business groups, self-start up groups, and so many other countless categories. A COI is a group of professionals and advisors that share business insights, technical expertise, challenges, and perspectives.
Unisex public toilets are public toilets that are not separated by gender or sex.
Apartheid was a system of racial segregation in South Africa.
Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregation process occurs during both mitosis and meiosis. Chromosome segregation also occurs in prokaryotes. However, in contrast to eukaryotic chromosome segregation, replication and segregation are not temporally separated. Instead segregation occurs progressively following replication.
Self-segregation or auto-segregation is the separation of a religious, ethnic, or racial group from other groups in a country by the group itself naturally. This usually results in decreased social interactions between different ethnic, racial or religious groups and can be classed as a form of social exclusion.
The origin and function of meiosis are currently not well understood scientifically, and would provide fundamental insight into the evolution of sexual reproduction in eukaryotes. There is no current consensus among biologists on the questions of how sex in eukaryotes arose in evolution, what basic function sexual reproduction serves, and why it is maintained, given the basic two-fold cost of sex. It is clear that it evolved over 1.2 billion years ago, and that almost all species which are descendants of the original sexually reproducing species are still sexual reproducers, including plants, fungi, and animals.
This glossary of genetics and evolutionary biology is a list of definitions of terms and concepts used in the study of genetics and evolutionary biology, as well as sub-disciplines and related fields, with an emphasis on classical genetics, quantitative genetics, population biology, phylogenetics, speciation, and systematics. Overlapping and related terms can be found in Glossary of cellular and molecular biology, Glossary of ecology, and Glossary of biology.
Non-random segregation of chromosomes is a deviation from the usual distribution of chromosomes during meiosis, that is, during segregation of the genome among gametes. While usually according to the 2nd Mendelian rule homologous chromosomes are randomly distributed among daughter nuclei, there are various modes deviating from this in numerous organisms that are "normal" in the relevant taxa. They may involve single chromosome pairs (bivalents) or single chromosomes without mating partners (univalents), or even whole sets of chromosomes, in that these are separated according to their parental origin and, as a rule, only those of maternal origin are passed on to the offspring. It also happens that non-homologous chromosomes segregate in a coordinated manner. As a result, this is a form of Non-Mendelian inheritance.
Trisomy X, also known as triple X syndrome and characterized by the karyotype 47,XXX, is a chromosome disorder in which a female has an extra copy of the X chromosome. It is relatively common and occurs in 1 in 1,000 females, but is rarely diagnosed; fewer than 10% of those with the condition know they have it.
