One chromosome contains one molecule of DNA. In eukaryotes the length of the DNA molecule is enormously large. Explain how such a long molecule fits into the tiny chromosomes seen at Metaphase.

Explanation

DNA is packaged in the cell in the following manner
(a) As nucleosome consists of Histone octamer around which the negatively charged DNA is wrapped around to form a nucleosome. A typical nucleosome contains 200 bp of DNA helix.
(b) Repeated units of nucleosomes then form chromatin in a nucleus). The nucleosomes represent the "Beads on String structure as seen in electron microscopic picture
(c) These are then further coiled and condensed at metaphase stage to form chromosomes.
(d) For packaging of chromatin at higher level, non histone proteins are required