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Old 12-12-2012, 01:19 AM   #466
lightgiver
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The Y chromosome is one of the 2 sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 50 million base pairs. DNA in the Y chromosome is passed from father to son, and Y-DNA analysis may thus be used in genealogy research. With a 30% difference between humans and chimpanzees, the Y chromosome is one of the fastest evolving parts of the human genome..The human Y chromosome is particularly exposed to high mutation rates due to the environment in which it is housed. The Y chromosome is passed exclusively through sperm, which undergo multiple cell divisions during gametogenesis... The human Y chromosome has lost 1,393 of its 1,438 original genes over the course of its existence..They found that human Y chromosome is able to "recombine" with itself, using palindrome base pair sequences. Such a "recombination" is called gene conversion...There is also a temperature-dependent sex determination system is found in some reptiles...



Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes..Animals produce gametes directly through meiosis in organs called gonads.. Males and females of a species that reproduces sexually have different forms of gametogenesis...Females have two X chromosomes, whereas males have one X and one Y chromosome...Triple X syndrome is a form of chromosomal variation characterized by the presence of an extra X chromosome in each cell of a human female..



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Last edited by lightgiver; 12-12-2012 at 01:33 AM.
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