Chromosomes in a dividing cell are duplicated and highly compact. At other times, though, they are singletons and more expanded. Until the recent advent of "chromosome painting" techniques, the expanded chromosomes were difficult to distinguish from one another. Image: Illustrations by Anatomy Blue
- Chromosomes are not sprinkled randomly around the inside of the nucleus. They occupy preferred positions.
- This nuclear organization reflects the functional state of each chromosome and of the genes it carries. The organization can change as a cell’s behavior changes and in disease.
- Identifying the locations that genes occupy within the nucleus—and seeing how these positions change under different conditions—is providing clues to how normal cells function and how some diseases, including cancer, arise.
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Ten years ago publication of the human genome sequence gave the world a blueprint for a human being. But just as a list of automobile parts does not tell us how a car engine works, the complete genome sequence—a list of the DNA “letters” in all the chromosomes of the human cell—did not reveal how the genome directs our cells’ day-to-day activities or allows an individual to develop from a fertilized egg into a functioning adult.
To better understand the way the genome as a whole orchestrates the symphony of biological activity called life, I and others in the new field of genome cell biology are examining how chromosomes, and the genes they house, are arranged within the three-dimensional space of the nucleus and how that organization influences their activities.
This article was originally published with the title The Inner Life of the Genome.