Chromosomes Organize Into 'Yarns': May Explain Why DNA Mutations Can Affect Genes Located Thousands of Base Pairs Away

Chromosomes are the molecular basis to genetic heredity, and are located inside the cell nucleus. New research shows that chromosomes fold in a series of contiguous “yarns”. These yarns bring harbor groups of genes and regulatory elements together so that they can work together during development. The new study shows the string of beads model that represent a chromosome, now folds up to form yarns on a string, where the yarn represents a group of genes. These yarns on a string can measure up to a few hundred to a million base pairs. Along with genes within the yarns, there are also “regulatory genomic elements,” or switches which control the activity of the neighboring cells. A group of genes that are in the same yarn will most likely meet up with a similar set of regulatory elements. The yarn model shows that the genes do not mix with other genes of different groups, which helps the cell regulate genes more easily. On the other hand, damaging one yarn can lead to mutation of all the genes of that group, or have the whole group of genes misbehave. This organization of genes allows for genes that are further apart from each other interact with each other. This model of “yarn chromosome” helps explain why mutations occur in genes that are far away from each other. This structure also provides a shortcut through the chromosome.