The mass of the 46 human chromosomes (which contain the instructions for life in almost all the cells of our body) has been measured with X-rays for the first time, discovering that it is approximately 20 times heavier than the DNA they contained , a mass much larger than previously expected.
This disparity suggests that there may be missing components yet to be discovered.
In a new study published in Chromosome Research , researchers led by researchers at UCL (University College London) used a powerful X-ray beam at the UK’s national synchrotron facility, Diamond Light Source, to determine the amount of electrons in a stretch of 46 chromosomes that they used to calculate mass. The measurement suggests that the 46 chromosomes in each of our cells weigh 242 picograms (trillionths of a gram) .
Each human cell normally contains 23 pairs of chromosomes, or 46 in total . Within these are four copies of 3.5 billion base pairs of DNA. In addition to DNA, chromosomes consist of proteins that serve a variety of functions, from reading DNA to regulating cell division processes to tightly packaging two-meter strands of DNA into our cells. But we still do not know what this difference between the measured mass and the expected mass may correspond to.
The implications of understanding chromosome mass could be important in the medical field, as they contain the instructions for life in almost every cell in our body.