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Nucleus: Structure and Function
Next Generation: MS.LS1.2 MS.LS1.2

Nucleus: Structure and Function

Author: Amanda Soderlind

Understand the definition and components of the nucleus

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Source: Images and Video Created by Amanda Soderlind

Video Transcription

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Welcome to this lesson today on the nucleus. In this lesson, we will be describing the structure and the function of the nucleus.

So the nucleus is a cellular organelle found in eukaryotic cells. So eukaryotic cells are described as cells that have a nucleus. So it makes sense that the nucleus would only be found in eukaryotic cells.

And an example of a eukaryotic cell would be our cells, for example, or any other animal cells. Those would all be eukaryotic cells because they have a nucleus.

The nucleus contains the cell's DNA. And we'll talk a little bit more about that in just a few moments here when we look at these diagrams. And the nucleus is basically the control center of the cell. So it's the brain of the cell or the control center that controls everything that's happening within the cell.

So we're going to take a look at these diagrams right here and explain a little bit more about the structure of the nucleus. So this diagram right here is just a drawing of any eukaryotic cell. We'll say that this is one of our cells.

So within our cells we have the nucleus and we have several other different organelles. But today we're just going to focus on the nucleus. So if we were to blow this up and take a look at this diagram here-- it's just a bigger picture of what we have in this diagram.

So the structure of the nucleus. Outside surrounding the nucleus, we have something called a nuclear envelope. And this nuclear envelope is a double layer membrane composed of two lipid bilayers.

And within it we have these pores. So these little black dots all over here are our pores in our nuclear envelope. And these pores are very important because they allow for RNA to leave the cell. And it also allows for the passage of certain ions or molecules.

And there's also many different types of proteins embedded within this membrane as well. But one of the most important parts of this are the pores, which selects RNA out. So in just a moment we're going to talk a little bit more about the importance of RNA and those pores.

Another structure of the nucleus is the nucleolus. So the nucleolus is a structure found inside of the nucleus. And the purpose of the nucleolus is to construct ribosome subunits.

So the subunits of ribosomes are made inside the nucleolus. And then they'll cross through those pores-- that I mentioned just a minute ago-- and into the cytoplasm of the cell.

And then once they're in the cytoplasm of the cell, they'll connect together to form a ribosome. And ribosomes are structures that help to build proteins within our cell. So they're very important.

The next structure we're going to take a look at here is chromatin. So chromatin is contained within the nucleus. And chromatin contains our genetic information.

So when chromatin condenses, it will form chromosomes. And chromosomes are visible when a cell divides. And the purpose of chromosomes is to allow for the passage of genetic information.

So normally this is what our genetic information looks like within the cell. But when the cell's preparing to divide, it will condense into those chromosomes that you might be familiar with. That looks something like this.

And so that allows for the passing of genetic information onto the new cell. And the nucleus helps to keep this genetic information organized and separate from the rest of the cell. So these are the different structures of the nucleus.

This lesson has been an overview on the structure and function of the nucleus.

Terms to Know

​A form of uncondensed DNA found within the nucleus of the cell.


A condensed form of DNA that occurs when the cell is dividing.


​DNA stores an organism’s genetic information.

Nuclear Envelope

A double membrane that surrounds the nucleus.


A structure found within the nucleus that produces subunits of ribosomes.


​A cell organelle found in eukaryotic cells that houses the DNA and controls activity within the cell.


A cell organelle responsible for synthesizing proteins.