sex chromosomes

其實……sex chromosome唔係長度唔同
d codon都係好多都唔同架……
大部份既allele都唔complementary

"Only a very small part of the X and Y chromosomes of humans can and do pair up during meiosis, (i.e. have complementary alleles.) In fact the bulk of each sex chromosome contains genes that have no corresponding alleles on the other type of sex chromosome. Thus, the short Y chromosome carries genes specific for male sex determination and sperm production, including the 'male' gene coding for the testis determining factor (TDF) that switches development of embryonic gonad tissue to testes early in embryonic development. Meanwhile the X chromosome carries an assortment of genes, very few of which are concerned with sex determination.

所以係唔得既
至少X chromosome冇TDF

！有！以色列做緊 ！