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Code Breakers

Scientists tease out the secrets of proteins that DNA wraps around

Jamming a week's worth of clothing into a carry-on suitcase is tough, but consider the challenge a human cell faces with its DNA. More than 6 feet of this double-stranded molecule, making up a cell's 23 pairs of chromosomes, must get stuffed into the cell's microscopic nucleus. Just as people might roll or fold their clothes in special ways to stuff a piece of luggage, cells have devised tricks of their own to cram in all their DNA. One trick is to tightly wind the DNA around complexes of proteins called histones, much as thread is coiled around a spool. The histone-DNA combos, in turn, are folded and refolded to make up individual chromosomes.

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