For the first time, scientists were able to accurately measure the mass of the human chromosome.
Using a powerful X-ray source at the UK's National Synchrotron Scientific Facility, the Diamond light source, physicists were able to determine the individual masses of all 46 chromosomes in human cells.
Curiosity
The Diamond Light Source already appeared on the pages of Futuroprossimo.it, two years ago. On that occasion, the powerful instrument managed to "read" the contents of very ancient papyri from Herculaneum that were still closed.
The masses of the chromosome turned out to be significantly higher than expected (about 20 times higher than the DNA contained in them). Depends on what? There is additional mass from other elements within the chromosome, the researchers say. Unknown elements, yet to be discovered.
The chromosome weighs 242 picograms
“It is the first time we have been able to precisely measure the masses of the chromosome,” says the biophysicist Ian Robinson from University College London.
Our measurement suggests that the 46 chromosomes in each of our cells weigh 242 picograms (trillionths of a gram). It is much heavier than we expectedassimo, indicates an excess mass. A mass at the moment inexplicable.
What are chromosomes
Chromosomes are small packets of DNA filiform that can be found in the cell nuclei of living organisms.
Each of them contains a molecule of DNA, which in turn contains the genetic instructions for the development and life of that organism. Humans have 23 pairs in total. To be precise, these are 22 pairs of numbered chromosomes (autosomes) and one pair of sex chromosomes.
Chromosomes prevent DNA from breaking down, helping to maintain its structure during the cell replication process.
They were first discovered in the XNUMXth century and scientists have learned a lot about their role since then, but there are also many things we don't understand.
Research that measured the mass of the chromosome
In this case, the scientists used a particle accelerator called a synchrotron to produce a powerful X-ray beam. When these X-rays pass through the chromosomes, their diffraction creates an interference pattern that the scientists use to create their own 3D reconstruction. high resolution.
The researchers imaged human white blood cells in metaphase (a phase of the cell cycle in which chromosomes are condensing) and just before cell division, when the 46 chromosomes inside each cell have tightly packed the DNA inside.
Using this technique, the researchers were able to determine the number of electrons, or electron density, in the chromosome. The mass of the electrons is well known; in fact, the rest mass of electrons is one of the fundamental physical constants. From this data, the research team was able to use this to calculate the chromosome mass.
What is there that we are missing?
It is not entirely clear what could explain the unexpected mass found by the researchers, but finding out would bring incalculable benefits to science, it would be a fundamental step forward.
A better understanding of the chromosome can have important implications for our health.
A large number of studies are being undertaken in medical laboratories to diagnose cancer from patient samples. Any improvement in our chromosome imaging abilities is valuable.
Archana Bhartiya, bioscientist at University College London.
