Chromosomal architecture refers to the three-dimensional organization of chromosomes within the nucleus of a cell. This structure is crucial for gene expression, DNA replication, and repair. Chromosomes are made up of DNA and proteins, which help package and manage the genetic material efficiently. The arrangement of chromosomes can influence how genes are activated or silenced. For instance, regions of euchromatin are loosely packed and accessible for transcription, while heterochromatin is tightly packed and generally inactive. Understanding chromosomal architecture is essential for studying genetic regulation and cellular function.