Eukaryotic chromosomes:

The huge amount  of genomic  DNA in a eukaryotic  cell is strongly  packaged  in chromosomes  contained  within  a specialized  organelle and  the nucleus. This very huge amount of eukaryotic nuclear the DNA is strongly packaged in chromosomes. By the exception of the sex chromosomes, diploid eukaryotic organisms like as humans have two copies of every chromosome one inherited from the father and one from the mother. The Chromosomes contain both protein and DNA. Most of the protein on a weight basis is histones but there are also several thousands of other proteins found in far less abundance and these are collectively known as NHP (nonhistone proteins). This nuclear DNA-protein complex is known as chromatin. The chloroplasts and mitochondria of eukaryotic cells also contain DNA but unlike the nuclear DNA this consists of double-stranded circular molecules resembling bacterial chromosomes.

In the nucleus, every chromosome contains a single linear double-stranded DNA molecule. Length of the packaged DNA molecule varies. In the humans, the longest is about 8.4 cm and the shortest DNA molecule in a chromosome is about 1.6 cm. In During the metaphase stage of mitosis  when the chromosomes align on the  mitotic  spindle  ready  for  segregation they are at their most condensed and range in size from only 1.3 m to 10 m long. Therefore the packing ratio, which is the ratio of the length of the linear DNA molecule to the length of the metaphase chromosome, is about 104. In the time period among the end of one mitosis and the start of the next like interphase the chromatin is more disperse.  Now the packing ratio is in the range 102-103.  Whole,  the extensive packaging of DNA in chromosomes results from three stages of folding including nucleosomes, 30 nm radial loops and filaments.