Scientists say human chromosomes are much heavier than they should be and they don’t know why

Scientists have found that human chromosomes, which contain instructions for life in nearly every cell in our bodies, weigh 20 times more than their home DNA, an advance that suggests the missing components of the genome have yet to be discovered. can.

A normal human cell normally has 23 pairs of chromosomes, or 46 in total, and contains four copies of the 3.5 billion molecule base pairs of DNA.

Along with DNA, chromosomes also contain proteins that perform a variety of functions such as reading DNA, regulating cell division, and tightly packaging and storing the two-meter strand of DNA in each of our cells.

In the research, University College London (UCL) scientists used a powerful X-ray beam at Britain’s National Synchrotron Facility – the Diamond Light Source – to determine the number of electrons in the propagation of 46 chromosomes. Which they then used to calculate the mass.

To estimate the number of electrons, the researchers used a technique called X-ray pycnography that involves the diffraction of X-ray beams and stitching together patterns as they pass through chromosomes.

They looked at chromosomes during the metaphase part of the cell division cycle—before they were about to split into two daughter cells, a stage when packaging proteins fold the DNA into very compact, precise structures.

conclusion, Published in the journal Chromosome Research, discovered that the 46 chromosomes in each of our cells weigh 242 picograms – a trillionth of a gram – and are about 20 times heavier than their DNA.

“This is heavier than we expected, and if repeated, points to unexplained excess mass in chromosomes,” senior author Ian Robinson, from the London Center for Nanotechnology at UCL, said in a statement.

Based on the results, scientists believe that there may be missing components of chromosomes that are yet to be discovered.

“Chromosomes have been examined by scientists for 130 years, but some parts of these complex structures are still poorly understood,” Robinson said.

“From the Human Genome Project we know the mass of DNA, but this is the first time we have been able to precisely measure the mass of the chromosomes that comprise this DNA,” he said.

According to the researchers, further studies are needed to find the source of this mysterious mass and they could have important implications for human health.

“There is a great deal of study of chromosomes used in medical laboratories to diagnose cancer from patient samples. Any improvements to our abilities to image chromosomes would be highly valuable,” said a PhD student at the London Center for Nanotechnology at UCL and author of the paper Lead author Archana Bharti said in a statement.


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