The nucleus contains most of a human cell’s genetic material.
It is a membrane-bound organelle found in most human cells. Inside, DNA is packaged with proteins into chromatin and chromosomes. The nucleus therefore stores the genetic instructions used to regulate cell activity, growth, and division.
A double membrane called the nuclear envelope surrounds the nucleus. Nuclear pores control traffic between the nucleus and cytoplasm, allowing substances such as messenger RNA to leave while regulating the entry of proteins and other molecules. The nucleolus, a dense region inside the nucleus, helps produce ribosomal components.
The word “most” matters because mitochondria also contain a small, separate genome. Mitochondrial DNA is inherited primarily through the egg cell and encodes some components involved in energy production. Mature human red blood cells lack a nucleus altogether, which gives them more room for haemoglobin but leaves them unable to divide or make new proteins.