What Does tetrad Mean
The notion of tetrad refers to a series of four elements that are related to each other . It is a group of four components that maintain a bond.
For example: "The ease of contagion, the lack of a vaccine, the absence of specific treatments and the lack of responsibility of many people constitute a worrying tetrad for doctors facing COVID-19 around the world" , " The writer told the detective's story in a tetrad of novels that must be read as a unit " , " Throughout the film a tetrad of melodies sounds that is repeated over and over again . "
In the field of astronomy , the idea of tetrad is used to refer to a succession of four total lunar eclipses that occurs in a period of a few months . The phenomenon is usually associated, in popular beliefs, with the imminence of a great tragedy .
There are those who find supposed allusions to tetrads in the Bible . Links are also established between tetrads and major historical events, such as the tetrad of 1493 and the expulsion of the Jewish community from Castile and Aragon or the tetrad of 1949 and the Six Day War .
In the field of biology , on the other hand, the concept of tetrad appears. In this case, the set of four chromatids that, in the first division of meiosis, are found in synapses is called a tetrad .
The tetrad arises when two homologous chromosomes, in prophase I of meiosis , replicate and pair. In this way, the tetrad is made up of four chromatids, two for each chromosome.