True or False: Chromatin adds an additional layer of regulation in eukaryotic gene expression.

Chromatin does indeed add an additional layer of regulation in eukaryotic gene expression. This structure consists of DNA wrapped around histone proteins, forming nucleosomes that can further organize into more complex configurations. The way chromatin is modified through processes such as acetylation, methylation, and phosphorylation directly influences gene accessibility and expression. For example, when chromatin is in an open, relaxed state (often referred to as euchromatin), genes are more accessible for transcription. In contrast, tightly packed chromatin (heterochromatin) generally restricts access and inhibits transcription.

Moreover, these chromatin modifications can be heritable, meaning they can influence gene expression throughout cell divisions and even across generations, adding another layer of complexity to how genes are regulated in eukaryotic organisms. Thus, the assertion that chromatin contributes to the regulation of gene expression is fundamentally correct.