A process that is carried out at the cellular level that results in the assembly, arrangement of constituent parts, or disassembly of chromosomes, structures composed of a very long molecule of DNA and associated proteins that carries hereditary information. This term covers covalent modifications at the molecular level as well as spatial relationships among the major components of a chromosome.

Any process that stops, prevents, or reduces the frequency, rate or extent of transcription mediated by RNA polymerase II.

The regionalization process that gives rise to the structural pattern of a chorion-containing eggshell such as those found in insects.

The chemical reactions and pathways involving piRNAs, Piwi-associated RNAs, a class of 24- to 30-nucleotide RNA derived from repeat or complex DNA sequence elements and processed by a Dicer-independent mechanism.

Any process that activates or increases the frequency, rate or extent of transcription from an RNA polymerase II promoter.

The chemical reactions and pathways resulting in the formation of piRNAs, Piwi-associated RNAs, a class of 24- to 30-nucleotide RNA derived from repeat or complex DNA sequence elements and processed by a Dicer-independent mechanism.

The ordered and organized complex of DNA, protein, and sometimes RNA, that forms the chromosome.

A compact and highly condensed form of chromatin.

A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent.