Chap. XII_interphase nucleus and cell cycle_English_2026

The Cell nucleus during interphase represents the functional state of the nucleus when the cell is not undergoing division. It serves as the control center of the cell and contains the genetic material in the form of chromatin. The interphase nucleus is surrounded by the nuclear envelope, which contains nuclear pores that regulate exchanges between the nucleus and the cytoplasm. It also contains the nucleolus, the site of ribosomal RNA synthesis and ribosomal subunit assembly. During interphase, the nucleus performs essential activities such as DNA replication, transcription, and regulation of gene expression.

The cell cycle is the sequence of events through which a cell passes between two successive divisions. It consists of interphase (G1, S, and G2 phases) and mitosis (M phase).

• During G1 phase, the cell grows and synthesizes proteins.
• During the S phase, DNA replication occurs.
• During G2 phase, the cell prepares for division.
• Finally, during mitosis, chromosomes are equally distributed into two daughter cells.