Anatomy of The Cell: Nucleus

Cells stained with blue fluorecent dye. The blue area is the nucleus. Image Credit: TenOfAllTrades

The nucleus, one of the most important parts of the eukaryote cell. In fact, it was one of the very first organelles to be discovered since it is one of the biggest and has our hereditary material in it: the DNA.

What is DNA?

DNA is a giant molecule which helps you reproduce. DNA holds all your biological data including your skin color, your eye color, hair color and the type of your hair.. you get the picture. Without the DNA, we wouldn’t be here. Not as we are right now at least.

3D model of the DNA molecule. Image credit: Zephyris

Alongside your hereditary information, the DNA is also a manual for your cell. It provides information on how to create the proteins your cell needs, how to function, when to die, when to divide etc. Since the DNA is such an important molecule, it is natural that it should be kept in the nucleus. At least when it comes to eukaryotes!! You also have to factor in the fact that in eukaryotes, the DNA can be pretty large: about 2 meters long in humans!

The Structure of The Nucleus

Detailed structure of the nucleus. Image credit: Mariana Ruiz

The most important structure present in the nucleus is the chromatin. The chromatin is the chain of DNA in a non-condensed form. When a cell wants to divide, the chromatin is condensed and forms what is called a chromosome. Chromosomes act like a condensed packet of information that helps your cells get the necessary copy of DNA when dividing. The number of chromosomes is different in animals. Humans have 46 chromosomes for example!

Condensation and formation of the chromosome. Image credit: Richard Wheeler

The nucleolus, is a relatviely large organelle within the nucleus that is mainly responsible for creating ribisomes.

The DNA and the nucleolus are sheltered from the rest of the cell by the nuclear envelope which has an outer and inner membrane. On the envelope, there are pores which allow different molecules to pass through the envelope. There are also ribosomes: tiny machines that translate your DNA to proteins necessary for cell function and survival.


Kent, M. (2016). Advanced biology.

Molecular Expressions Cell Biology: The Cell Nucleus. (2019). Retrieved from


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