A younger cell’s game. Cells control harmful transposons in DNA by wrapping them tightly around nucleosomes and packing them into chromatin fibers. The ability to maintain control of harmful transposons diminishes as cells age. Image Credit: Darryl Leja/National Human Genome Research Institute (Click image to enlarge)
A nucleosome is the basic repeating unit of eukaryotic chromatin. In a human cell, about six feet of DNA must be packaged into a nucleus with a diameter less than a human hair. A single nucleosome consists of about 150 base pairs of DNA sequence wrapped around a core of histone proteins. The nucleosomes are arranged like beads on a string. They are repeatedly folded in on themselves to form a chromosome.
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