Which cellular organelle contains most of the genetic material of a cell?

The nucleus is the cellular organelle that contains the majority of a cell's genetic material in the form of DNA. This genetic material is organized into chromosomes, which are crucial for storing and transmitting genetic information during cell division. The nucleus serves as the control center of the cell, regulating gene expression and mediating the replication of DNA during the cell cycle.

This organelle is surrounded by a double membrane known as the nuclear envelope, which separates its contents from the cytoplasm and protects the DNA from damage. Within the nucleus, the nucleolus can also be found, which is responsible for the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomes, further emphasizing the nucleus's central role in the cell's functions.

Other organelles mentioned do not primarily house genetic material. Mitochondria do contain some DNA, known as mitochondrial DNA, but it represents a small fraction of the total genetic material in the cell. The endoplasmic reticulum and Golgi apparatus play key roles in the synthesis, processing, and transport of proteins and lipids, but they do not contain significant portions of genetic material. Therefore, the nucleus is unequivocally identified as the organelle responsible for containing the vast majority of a cell's genetic material