Scientists Decipher Y Chromosome

Code Cracked on Genes that Make Men 'Men'

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Above, the sex chromosomes -- X and Y -- under the microscope. Howard Hughes Medical Institute hide caption

See all 23 pairs of human chromosomes under the microscope.
toggle caption Howard Hughes Medical Institute

Researchers have finally unraveled the chromosome that determines maleness in humans. There's no gene to explain why men insist on changing the TV channel all the time, but other secrets of the Y chromosome are revealed in two new studies. NPR's Richard Harris reports.

Scientists have known for decades that the Y chromosome carries a gene that turns a fetus into a male. But the chromosome was otherwise dismissed as a genetic wasteland. Not true, according to the two papers published in the journal Nature. The Y chromosome contains 78 genes. What's more, those genes are encoded in the chromosome forward and backward, in the form of genetic palindromes millions of DNA letters long.

Most chromosomes come in identical pairs, so if a chromosome is injured, it can make a repair to a gene by copying it from its duplicate chromsome. The Y chromosome has no duplicate. But, it turns out, its palindromes provide backup copies of its critical genes, so it can repair itself when it gets damaged by mutations.

Scientists say deciphering the genetic code of the Y chromosome is a small but important step in understanding the deep biological differences between men and women.



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