Chromatin material is divided into two types based on dye retention.
(i) Euchromatin: The part of the chromosome which becomes light colored when stained with alkaline dye is called euchromatin. This region contains a large amount of DNA and plays an important role in heredity. It synthesizes mRNA.
(ii) Heterochromatin: The part of the chromosome which becomes dark when stained with alkaline dye is called heterochromatin. These regions contain small amounts of DNA and do not play a significant role in heredity. It does not synthesize mRNA.