Sex Chromosomes

Topics: Chromosome, Aneuploidy, Y chromosome, X chromosome / Pages: 13 (3096 words) / Published: Jan 19th, 2013
Sex Chromosomes

Introduction Few people every wonder or care about their gender and why they are male or female.. Sex-determination system is a complex but fascinating progress, especially within reptiles, birds and insects. All living organisms begin with one eukaryotic cell; inside the nucleus of each cell contain thread-like structures called chromosomes. Chromosomes are once theorized to be derived from autosomes (chromosomes that are not sex chromosomes) and have changed into specific chromosomes throughout evolution. All living organisms contain chromosomes, but they can range widely between different organisms. For example, inside the nuclei of human cells contain 46 chromosomes (22 pairs of autosomes and one pair of sex chromosomes) while butterflies have 380 chromosomes. There are two types of sex chromosomes present in the human body, X (female) and Y (male) chromosomes. The combination of these two chromosomes decides the gender of the offspring. Interestingly, the X and Y in certain species mammals are backwards, where the male would have the X chromosome and the female with a different combination. This unusual system is believed to be derived from the ancestral X and Y chromosome. The X and Y chromosome is essential for living organisms to function but the presence and absence of either the X or Y chromosome can be related to numerous disorders and abnormalities.

X Chromosome
Function
The X chromosome is one of the two sex-determining chromosomes in a variety of species. Each individual will always have one X chromosome present. The X chromosome contains essential genes that the human body cannot live without. Cells in the female body contain two XX chromosomes, whereas males only have one X and one Y chromosome. In females, the initial X chromosome is retained from their mother, and the second X chromosome comes from their father. The presence of the X chromosome in combination with the X or Y chromosome differentiates the two



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