Sex chromosome , either of a pair of chromosomes that determine whether an individual is male or female. The sex chromosomes of human beings and other mammals are designated by scientists as X and Y. In humans the sex chromosomes consist of one pair of the total of 23 pairs of chromosomes. The other 22 pairs of chromosomes are called autosomes. The X chromosome resembles a large autosomal chromosome with a long and a short arm.
The Y-Chromosome in Animals
Nettie Stevens Discovered the XY Sex-determination System - Fact or Myth?
By University of Vienna January 7, New methods have shown that platypus has ten sex chromosomes. The sex chromosomes genetically define the developmental fate of an embryo to become a male or a female individual, and usually appear as one pair of morphologically different chromosomes between sexes. For example, women have one pair of XX chromosomes, while men have one pair of XY chromosomes. Platypus have five pairs of sex chromosomes forming an unusual chain shape, while the sex chromosomes of emu and duck are not as different between sexes as those of humans. These works are the results of international collaboration between scientists from Austria, Australia, China and Denmark, and are published as research papers together on Jan.
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XY sex-determination system
The Y chromosome is one of the two sex chromosomes in humans the other is the X chromosome. The sex chromosomes form one of the 23 pairs of human chromosomes in each cell. The Y chromosome spans more than 59 million building blocks of DNA base pairs and represents almost 2 percent of the total DNA in cells.
Sex Chromosomes focuses on the study of sex chromosomes, including human chromosomal abnormalities, behavior and characteristics of chromosomes, and cell division. The book first offers information on the chromosomal basis of sex determination, as well as development of the cell theory, mitosis, fertilization, meiosis, and discovery of sex chromosomes. The publication also ponders on the mitosis, meiosis, and formation of gametes. Discussions focus on the special characteristics of sex chromosomes, abnormalities of cell division, and sexual differentiation.