Scientists puzzled by 'unexplained excess mass' lurking in human chromosomes

The spread of 46 human chromosomes, with added color. (Image credit: Archana Bhatiya et al)

How much do you weigh? No, not your body weight (we're not here to judge) — but the weight of your chromosomes, those X-shaped bundles of genetic instructions that make you you?

If you don't know offhand, then scientists have you covered. Using one of the U.K.'s most powerful X-ray beams, a team of researchers recently measured the mass of the 46 human chromosomes.

The results were surprising: Each chromosome was about 20 times heavier than the DNA contained inside them — a much greater mass than the researchers anticipated, according to their study published March 31 in the journal Chromosome Research.

"Our measurement suggests the 46 chromosomes in each of our cells weigh 242 picograms (trillionths of a gram)," study co-author Ian Robinson, a professor of physics at University College, London, said in a statement. "This is heavier than we would expect, and, if replicated, points to unexplained excess mass in chromosomes."

The U.S. government-run Human Genome Project revealed, among other things, the mass of DNA molecules — however, the weight of the chromosomes that house these molecules remained a mystery. Understanding this could lead to further insights about the complex structure of chromosomes, which are studied extensively by medical labs for things like cancer diagnoses, according to the researchers.