Page 17 - The Miracle of Creation in DNA

Condensed
chromosome Condensed
chromatin
Extended
chromatin

Coiled
nucleosomes

DNA double Nucleosomes
helix

The DNA molecule in the nucleus is wrapped up in special covers called
chromosomes. The total length of a DNA molecule wrapped up in the
chromosomes is 1 metre. A chromosome is one nanometre thick, in other words a
billionth of a metre. How is a 1-metre long DNA molecule contained in such a tiny
space?
Chromosome packages are actually made up of much smaller special container
systems. The DNA molecule is first wound around special proteins called histones,
just like a cotton reel. Thus, they form structures called nucleosomes. These
nucleosomes are specially designed to protect the DNA and stop it being damaged.
When nucleosomes are strung on to one another, they form chromatins. Closely
wound coiled loops form with the chromatin. In this way, a superb creation
squeezes the DNA molecule into a tiny space only a billionth of its length.

DNA: The Data Source of Life 15