Heterochromatin

Heterochromatin is a segment of chromatin in a cell consisting of a section of deoxyribonucleic acid (DNA) that is not involved in DNA replication, that is, in the synthesis of new DNA strands. Thus, a heterochromatic segment of DNA is usually an inactive but fixed version of genetic information. But unlike most parts of the chromatic material, this region contains one or more sequences of repeats identical to the large subunit of DNA (BTAG). Strictly speaking, they are not completely repetitive sequences of the genome - they are only flanking BTAG segments. Despite this, certain structures within BTAGS - including genes and