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Cytoplasm: Structure and Function

Cytoplasm: Structure and Function

Author: Amanda Soderlind

Understand the definition and components of cytoplasm

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The Cytoplasm

Source: All images created by Amanda Soderlind

Video Transcription

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In this lesson today, we are going to talk about the cytoplasm of a cell and discuss its structure and function within the cell. So the cytoplasm is the part of the cell that fills the space between the plasma membrane and the nucleus. So I have a picture of a cell over here. We have our plasma membrane on the outside of the cell and our nucleus in the middle or inside of the cell. So the cytoplasm is everything that fills that space between the plasma membrane and the nucleus. So it includes all of the organelles as well. So when we're discussing the cytoplasm, we're talking about the inside of the cell, everything within the cell except for the nucleus.

The jelly-like fluid of the cytoplasm is called the cytosol. So if we're talking just about this jelly-like fluid-- we're not talking about any organelles. If we're discussing just the jelly-like fluid that fills the inside of the cell as part of the cytoplasm, it is called the cytosol.

The cytoplasm is made up mostly of water. And, like we said, it contains all of the cell organelles, including the cytoskeleton. And also, many chemical reactions and processes happen within the cytoplasm. So it has a very important role in the cell in order to contain all of those organelles. It acts as sort of like a cushion for the organelles. There's several different ions and proteins dissolved in it that help in chemical reactions. And many of these reactions and processes will actually take place within the cytoplasm, as I mentioned earlier.

So we're going to talk a little bit about the cytoskeleton now. And the cytoskeleton is a part of the cell contained in the cytoplasm that acts as structure and support for the cell. So think of your skeleton, for example, and the role that your skeleton plays. It acts to support your body and give your body structure. And this is similar to the cytoskeleton of a cell. It has kind of some of the same roles. It acts as structure and support for that cell. It helps it to maintain its shape and support the cell as a whole.

So the cytoskeleton is composed of three different parts, the microtubules, microfilaments, and intermediate filaments. So these are the three parts of the cytoskeleton. The microtubules are these structures right here. And the microtubules are the largest parts of the cytoskeleton. And they move cell parts, and they help to organize the cell. So this is what a microtubule might look like in a cytoskeleton.

Microfilaments have this structure here. And microfilaments act to reinforce parts of the cell, and they also help to anchor membrane proteins. And the intermediate filaments, this structure here, are the third part to our cytoskeleton. And intermediate filaments help to add strength. So they're adding strength to the cytoskeleton, allowing it to be more strong.

And they also help to anchor actin and myosin, which you'll learn in later lessons are an important part of muscle contractions. So the three parts of our cytoskeleton are microfilaments, intermediate filaments, and microtubules. So this lesson has been an overview on the structure and function of the cytoplasm, as well as an introduction into the structure and function of the cytoskeleton.

Terms to Know

The jellylike fluid that supports the cell between the nucleus and the plasma membrane. The cytoplasm includes the cytosol, the cytoskeleton, and organelles (other than the nucleus and its contents).


The protein structure that provides support to the cell - much like the bony skeleton supports the human body.


The liquid found inside the cytoplasm that is mostly composed of water.