Our bodies are made of over 36 trillion cells. Within each cell’s nucleus are chromosomes – 23 pairs to be exact (one set from each parent). In order to fit within each cell, chromosomes are tightly coiled around proteins called histones. Chromatin is the material that makes up chromosomes (consisting of DNA and proteins) and acts as the packaging system to compact the chromosome. Chromatin packing is necessary because within one cell, if the DNA were to be stretched out and straight, it would be around 2 meters long. If the DNA for all of your body’s cells were stretched out, it would be about 74 billion kilometers. For some perspective, that is around 500 times the distance from the Earth to the Sun.
So, how does chromatin packing work?