2.4 Lesson 4: Nucleus
Nucleus
- The nucleus is often called the “brain” of the cell as many cellular functions and the production of proteins originate from this structure.
- The nucleus contains most of the genes in a cell.
- Additional genes are located in the mitochondria
- The nucleus is separated from the cytoplasm by a double membrane called the nuclear envelope.
- The envelope is perforated by pores.
- A protein structure called a pore complex lines each pore, regulating the passage of certain large macromolecules and particles. Within the nucleus, the DNA and associated proteins are organized into discrete units called chromosomes, structures that carry the genetic information.
- A typical human cell has 46 chromosomes.
- Within the nucleus, the nuclear DNA and associated proteins are organized into fibrous materials, called chromatin.
- A ribosome is composed of two subunits that combine to carry out protein synthesis.