Final answer:
Histone methylation can lead to either denser or looser DNA packing depending on the specific methylation pattern, often resulting in transcriptional repression and denser nucleosome packing, though some methylation marks are associated with active gene expression.
Step-by-step explanation:
The methylation of histone tails can lead to either looser or denser packing of DNA; the outcome depends on the specific methylation pattern. In general, histone methylation is associated with transcriptional repression, leading to denser packing of nucleosomes and reduced gene expression. However, this is not always the case as certain methylation marks on histones are linked to active gene expression and thus can result in a looser DNA conformation that allows transcription factors to access the DNA more easily. Comparatively, histone acetylation is more clearly associated with loose packing of nucleosomes and transcriptional activation.