What is special about sex chromosomes?

Answer 1

Sex chromosomes can be either x or y: x+x=girl, x+y= boy.

yyx and xxy occur sometimes but these children have developmental problems and are infertile. xxy is called Klinefelter's syndrome.

Because there are some alleles attached to the x chromosome that cannot be paired with a y chromosome, there are some conditions that a male can get but are rare for a female. Colour blindness and haemophilia are conditions that are carried on the x chromosome, females have two x chromosomes so the condition does not manifest itself whereas males have one x chromosome so that chromosome can dominate.

Answer 2

Sex chromosomes determine an individual's biological sex, with females typically having two X chromosomes (XX) and males having one X and one Y chromosome (XY). These chromosomes carry genes that play a crucial role in sexual development and reproduction. Variations in sex chromosome composition can result in conditions such as Turner syndrome (XO), Klinefelter syndrome (XXY), and Triple X syndrome (XXX).