What is the characteristic of heterochromatin compared to euchromatin?

Heterochromatin is characterized by its tightly packed structure, which makes the DNA less accessible for transcription processes. This dense packing plays a crucial role in regulating gene expression, as genes located in heterochromatin regions are typically not actively expressed. The compact nature of heterochromatin contrasts with euchromatin, which is more loosely organized and generally more accessible to transcription machinery, allowing for active gene expression.

In summary, the defining feature of heterochromatin is that its tightly packed DNA makes it less accessible for transcription, thereby contributing to the regulation of gene expression in the cell.