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Non-human mammals use several genes on the Y chromosome. [citation needed] Not all male-specific genes are located on the Y chromosome. The platypus, a monotreme, use five pairs of different XY chromosomes with six groups of male-linked genes, AMH being the master switch. [8]
The accepted hypothesis of XY and ZW sex chromosome evolution in amniotes is that they evolved at the same time, in two different branches. [84] [85] No genes are shared between the avian ZW and mammal XY chromosomes [26] and the chicken Z chromosome is similar to the human autosomal chromosome 9, rather than X or Y.
X chromosome carry about 1500 genes, more than any other chromosome in the human body. Most of them code for something other than female anatomical traits. Many of the non-sex determining X-linked genes are responsible for abnormal conditions. The Y chromosome carries about 78 genes.
The Y chromosome is one of two sex chromosomes in therian mammals and other organisms.Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining chromosome because the presence of the Y chromosome causes offspring produced in sexual reproduction to be of male sex.
Most mammals, including humans, have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. In the absence of a Y chromosome, the fetus will undergo female development. This is because of the presence of the sex-determining region of the Y chromosome, also known as the SRY gene. [5]
The SRY gene, normally found on the Y chromosome, plays an important role in sex determination by initiating testicular development. In about 80 percent of XX males, the SRY gene is present on one of the X chromosomes. [16] [25] The condition results from an abnormal exchange of genetic material between chromosomes (translocation).
The cells of those born male contain an X chromosome and a Y chromosome that make a pair and give instructions on which genes should be expressed in the body, the researchers said.
The SHOX gene in the PAR1 region is the gene most commonly associated with and well understood with regards to disorders in humans, [17] but all pseudoautosomal genes escape X-inactivation and are therefore candidates for having gene dosage effects in sex chromosome aneuploidy conditions (45,X, 47,XXX, 47,XXY, 47,XYY, etc.).