Final answer:
Non-histone protein addition and chemical modifications such as acetylation and methylation enhance the formation of heterochromatin, a tightly packed form of chromatin that silences gene expression.
Step-by-step explanation:
The molecular processes that will enhance the formation of higher-order structure in heterochromatin involve the addition of non-histone proteins to the nucleosomes. Histones and DNA initially combine to form nucleosomes, which are further compacted via interactions with non-histone proteins. This compaction is a step towards the creation of heterochromatin, a tightly packed form of chromatin that generally contains genes that are not actively transcribed.
The transition from a less condensed chromatin structure (euchromatin) to a more condensed structure (heterochromatin) includes changes in the levels and types of associated proteins, as well as chemical modifications such as acetylation and methylation of histones. These chemical alterations help recruit additional proteins that can further condense the chromatin, making it inaccessible for transcription and thus silencing associated genes.