Introduction to the Cytoskeleton - Online Tutor, Practice Problems & Exam Prep

The cytoskeleton is a network of elongated proteins in the cytoplasm, crucial for maintaining cell shape, structure, movement, and bio-signaling. It consists of three main components: microfilaments, intermediate filaments, and microtubules. Microfilaments, made of actin proteins, are the smallest, while intermediate filaments vary in protein composition. Microtubules, the largest, are formed from tubulin proteins. Together, these structures fill the cytoplasm, playing vital roles in cellular functions and organization.

Introduction to the Cytoskeleton

In this video, we're going to begin our introduction to the cytoskeleton. And so the cytoskeleton, as implied by the cyto prefix, is a network of elongated proteins that are found in the cytoplasm of a cell, and the cytoskeleton is going to have multiple different functions. Now also implied by the term cytoskeleton, it has a resemblance to our own skeletons. And so just like our skeletons give our bodies their shape and structure, the cytoskeleton of cells does something similar, and so its functions include providing cell shape, as well as cell structure as well. But once again, we know that the cytoskeleton has multiple different functions. So not only does it provide the cell with its shape and structure, but it's also very important for cell movement, transportation, and bio signaling as well. Now, really there are 3 major components of the cytoskeleton and we've got those 3 major components numbered down below here and those are the microfilaments, the intermediate filaments, and the microtubules. And so the microfilaments are the smallest component of the cytoskeleton. They're the smallest in size and usually, microfilaments are going to be made of thin rods of repeating actin proteins. And so actin is the name of a protein that will repeatedly come together to build microfilaments. Now intermediate filaments, as their name implies, are intermediate in size. And so that means that it's going to be right in the middle. It's going to be larger than microfilaments, but smaller than microtubules. Intermediate filaments turn out that they are made of a lot of different types of proteins, and so they can be made of variable proteins. Now the microtubules, on the other hand, are going to be the largest component of the cytoskeleton. So they are the largest in size. And as their name implies with the tubule here, they are forming these large tubes that are made up of repeating tubulin proteins. And so these tubulin proteins will repeatedly come together to build the microtubules. And so let's take a look at our image down below to get a better idea of this cytoskeleton here. And so notice that we're saying that the cytoskeleton has somewhat of a resemblance to our own skeletons here. And so you can see that through, fluorescence microscopy, we can actually turn components of the cytoskeleton into different colors. Just like you can see here that the skeleton hand here is having different colors. And so notice over here on the far left, we're showing you the microfilaments. And in this image here, you can see that the components of the microfilaments are filled, are colored in red here. And those red, you can see, are filling up the cell, so they're found throughout the cytoplasm of the cell. And also, microfilaments are going to be the smallest in diameter as we indicated up above. So in terms of diameter, this way, they are the smallest in diameter from this end to this end right here. And so next what we have are the intermediate filaments here in the middle, and the intermediate filaments, as we indicated, are intermediate in size, so they're a little bit longer here than the microfilaments, and you can see that they are shown in green here in this image. And then the microtubules, which are the largest in size, they're going to come together to form this large tube that you see over here, and they're also colored in green over here in this image as well. And so what you'll notice is that the cytoskeleton really fills up the entire space of the cytoplasm of a cell. And once again, it plays very very important roles for giving the cell its shape, its structure, providing movement, transportation, and biosignaling. And so this here concludes our introduction to the cytoskeleton and we'll be able to apply these concepts as we move forward in our course. So I'll see you all in our next video.

Microfilaments are made of repeating subunits of:

• A. Actin proteins
• B. Tubulin proteins
• C. Micro proteins
• D. A variety of proteins

Which of the following is NOT a part of the cytoskeletal system of a cell?

• A. Microtubules
• B. Intermediate Filaments
• C. Chromatin
• D. Microfilaments

Here’s what students ask on this topic:

What are the main functions of the cytoskeleton in a cell?

The cytoskeleton has several crucial functions in a cell. It provides the cell with its shape and structural integrity, much like a skeleton does for the human body. Additionally, the cytoskeleton is essential for cell movement, enabling cells to change shape and migrate. It also plays a vital role in intracellular transport, facilitating the movement of organelles and vesicles within the cell. Furthermore, the cytoskeleton is involved in bio-signaling, helping to transmit signals from the cell membrane to the interior, which is crucial for various cellular processes.

What are the three main components of the cytoskeleton?

The cytoskeleton is composed of three main components: microfilaments, intermediate filaments, and microtubules. Microfilaments are the smallest and are made up of actin proteins. Intermediate filaments are of intermediate size and can be composed of various proteins, providing mechanical support to the cell. Microtubules are the largest components, formed from tubulin proteins, and they play a key role in maintaining cell shape, enabling intracellular transport, and facilitating cell division.

How do microfilaments differ from microtubules in terms of structure and function?

Microfilaments and microtubules differ significantly in both structure and function. Microfilaments are the smallest components of the cytoskeleton, composed of actin proteins arranged in thin rods. They are primarily involved in maintaining cell shape, enabling cell movement, and facilitating muscle contraction. In contrast, microtubules are the largest components, formed from tubulin proteins that create hollow tubes. Microtubules are crucial for maintaining cell shape, providing tracks for intracellular transport, and playing a key role in cell division by forming the mitotic spindle.

What proteins make up microfilaments and microtubules?

Microfilaments are primarily composed of actin proteins. Actin molecules polymerize to form long, thin rods that make up the microfilaments. On the other hand, microtubules are made up of tubulin proteins. Tubulin dimers, consisting of α-tubulin and β-tubulin, polymerize to form the hollow tubes that constitute microtubules. These structural proteins are essential for the various functions that microfilaments and microtubules perform within the cell.

What role do intermediate filaments play in the cytoskeleton?

Intermediate filaments play a crucial role in providing mechanical support and stability to cells. They are of intermediate size compared to microfilaments and microtubules and can be composed of various proteins, such as keratins, vimentin, and lamins. These filaments help maintain cell integrity by resisting mechanical stress and distributing tension across the cell. They also play a role in anchoring organelles in place and are involved in cell signaling and the formation of the nuclear lamina, which supports the nuclear envelope.