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

The cytoskeleton is a network of elongated proteins in the cytoplasm, providing cell shape, structure, movement, and bio-signaling. It consists of three main components: microfilaments, made of actin proteins; intermediate filaments, composed of various proteins; and microtubules, formed from tubulin proteins. Cilia and flagella, both made of microtubules, facilitate cell movement. Cilia are short, hair-like structures that can move objects or the cell, while flagella are longer, whip-like tails primarily used for cell propulsion.

Introduction to the Cytoskeleton

In this video, we're going to begin our introduction to the cytoskeleton. The cytoskeleton, as implied by the prefix 'cyto', is a network of elongated proteins that are found in the cytoplasm of a cell, and it has multiple different functions. The term cytoskeleton suggests a resemblance to our own skeletons. Just like our skeletons give our bodies their shape and structure, the cytoskeleton of cells does something similar, including providing cell shape and 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 is also very important for cell movement, transportation, and bio signaling as well. Now, there are 3 major components of the cytoskeleton, which are the microfilaments, the intermediate filaments, and the microtubules. The microfilaments are the smallest component of the cytoskeleton. They are made of thin rods of repeating actin proteins. Actin is the name of a protein that repeatedly comes together to build microfilaments.

Intermediate filaments, as their name implies, are intermediate in size. That means they are larger than microfilaments but smaller than microtubules, and they can be made of various proteins. On the other hand, microtubules are the largest component of the cytoskeleton. They form large tubes made up of repeating tubulin proteins, which come together to build the microtubules.

Let's take a look at our image down below to get a better idea of the cytoskeleton. Notice that the cytoskeleton resembles our own skeletons. Through fluorescence microscopy, we can turn components of the cytoskeleton different colors, as evidenced by the skeleton hand shown here having different colors. On the far left, the microfilaments are colored in red, illustrating their presence throughout the cytoplasm of the cell and highlighting that they are the smallest in diameter.

In the middle, the intermediate filaments are shown in green and are intermediate in size. The microtubules, which are the largest in size, form a large tube and are also colored in green in this image. The cytoskeleton fills up the entire space of the cytoplasm of a cell and plays very important roles in providing the cell its shape, structure, movement, transportation, and biosignaling.

This concludes our introduction to the cytoskeleton, and we'll be able to apply these concepts as we move forward in our course. I'll see you all in our next video.

What component of the cytoskeletons do motor proteins use to transport vesicles?

• A. Actin.
• B. Microfilaments.
• C. Microtubules.
• D. Intermediate filaments.

Cilia & Flagella

In this video, we're going to distinguish between cilia and flagella. And so the microtubules that we introduced in our last lesson video as one of the major components of the cytoskeleton are actually a major structural component of 2 cellular structures, cilia and flagella. And both cilia and flagella provide cell movement, which means that the microtubules are very important for cell movement as we introduced in our last lesson video. And so down below, we're going to distinguish between cilia and flagella. Now cilia consist of multiple short hair-like structures that move like oars and can either move objects in the surroundings relative to the cell or they can help provide cell movement itself, allowing the cell to move throughout its environment.

Now flagella, on the other hand, instead of being short, they are actually much longer, tail-like structures that actually move like a whip in order to provide cell movement. And so flagella typically are not going to be used to move other objects in the surrounding like what cilia can sometimes be used for. Flagella are mainly used to provide cell movement. And so down below, we can take a look at our image to distinguish cilia and flagella. And so over here on the left-hand side, we're showing you a scanning micrograph of cilia.

And so, you can see that these structures that you see here are the short hair-like structures that we were talking about before that can move like oars in order to either move objects in the surroundings or to move the cell itself. And so, notice that there are multiple cilia here and, they are shorter hair-like structures. Now over here on the right-hand side, we're showing you a scanning electron micrograph of some sperm cells. And so these sperm cells have flagella. And so you can see that here is the body of the cell and the long tail that comes off of the body of the cell right here are referred to as the flagella.

And so these tails are much longer than the short cilia. And, once again, they move like whips to provide cell movement. And so this here concludes our introduction to cilia and flagella and how they're both made of microtubules, which means that microtubules are important for cell movement. And so, we'll be able to get some practice applying some of the concepts that we've learned here as we move forward in our course. So I'll see you all in our next video.

In human cells, ___________________ are used to move a cell within its environment while ___________________ are used to move objects in the environment relative to the cell.

• A. Cilia, pseudopodia.
• B. Flagella; cilia.
• C. Cilia; flagella.
• D. Microfilaments; microtubules.

Here’s what students ask on this topic:

What are the main components of the cytoskeleton?

The cytoskeleton consists of three main components: microfilaments, intermediate filaments, and microtubules. Microfilaments are the smallest and are made of actin proteins. Intermediate filaments are of medium size and are composed of various proteins, providing structural support. Microtubules are the largest, formed from tubulin proteins, and are crucial for cell movement, transportation, and bio-signaling. Together, these components give the cell its shape, structure, and ability to move and communicate.

How do cilia and flagella differ in structure and function?

Cilia and flagella are both made of microtubules but differ in structure and function. Cilia are short, hair-like structures that move like oars, either moving objects around the cell or helping the cell itself move. Flagella, on the other hand, are long, whip-like tails primarily used for cell propulsion. While cilia can move objects in the cell's surroundings, flagella are mainly used to move the cell through its environment.

What roles do microfilaments play in the cell?

Microfilaments, the smallest components of the cytoskeleton, are primarily made of actin proteins. They play several crucial roles in the cell, including providing structural support, enabling cell movement, and facilitating cell division. Microfilaments are also involved in intracellular transport and help maintain the cell's shape by forming a network just beneath the cell membrane.

What proteins make up intermediate filaments, and what is their function?

Intermediate filaments are composed of various proteins, including keratins, vimentin, and lamins, among others. These filaments provide mechanical support to cells, helping them withstand stress and maintain their integrity. They are crucial for maintaining cell shape, anchoring organelles, and forming the nuclear lamina, which supports the nuclear envelope.

How do microtubules contribute to cell movement?

Microtubules, the largest components of the cytoskeleton, are made of tubulin proteins and play a significant role in cell movement. They form the structural basis of cilia and flagella, which are essential for cell motility. Microtubules also facilitate intracellular transport by serving as tracks for motor proteins that move organelles and vesicles within the cell. Additionally, they are involved in cell division by forming the mitotic spindle, which separates chromosomes during mitosis.