X like X chromosome

X as in X chromosome

The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals (the other is the Y chromosome).  T he X chromosome was named for its unique properties by early researchers, which resulted in the naming of its counterpart Y chromosome, for the next letter in the alphabet, after it was discovered later.

Each person normally has one pair of sex chromosomes in each cell.  Females have two X chromosomes, whereas males have one X and one Y chromosome.  Both males and females retain one of their mother's X chromosomes, and females retain their second X chromosome from their father.  Since the father retains his X chromosome from his mother, a human female has one X chromosome from her paternal grandmother (father's side), and one X chromosome from her mother.

The typical number of chromosomes in a human cell is 46 -- two pairs of 23 -- holding an estimated 25,000 genes. One set of 23 chromosomes is inherited from the biological mother (from the egg), and the other set is inherited from the biological father (from the sperm).

A chromosome abnormality reflects an abnormality of chromosome number or structure, i.e. when an individual is missing either a chromosome from a pair (monosomy) or has more than two chromosomes of a pair (trisomy).

 An example of a condition caused by numerical abnormalities is Down Syndrome, also known as Trisomy 21 (an individual with Down Syndrome has three copies of chromosome 21, rather than two).  Turner Syndrome is an example of monosomy, where the individual - in this case a female - is born with only one sex chromosome, an X.

Isn’t it unbelievable how our bodies function?  Be aware every day of this wonder, keep your body healthty and treat it with respect.  You only have one!