Question

Describe the structure and function of the cytoskeleton. (pages \(54-55\) )

Short answer

The cytoskeleton is a complex network of protein fibers in the cytoplasm, composed of microfilaments, intermediate filaments, and microtubules. Microfilaments, also known as actin filaments, maintain cell shape by resisting compression and support the cell's structure. Intermediate filaments provide mechanical strength to cells and maintain their shape, as well as the positions of organelles within the cell. Microtubules support the overall structure of the cell, maintain cell shape, and act as tracks for organelle movement and chromosome segregation during cell division. Overall, the cytoskeleton plays a crucial role in maintaining cellular structure, providing mechanical support, facilitating cell movement, and organizing the internal components of the cell.

Step-by-step solution

Introduction to Cytoskeleton

The cytoskeleton is a complex network of proteins fibers in the cytoplasm that helps maintain cell shape, protect the cell, and enable cellular motion. It is composed of three major types of protein fibers: microfilaments, intermediate filaments, and microtubules.

Microfilaments

Microfilaments, also known as actin filaments, are the smallest fibers with a diameter of about \(6-7\) nm. They are composed of actin proteins that bind together to form long chains. Their primary function is to maintain cell shape by resisting compression, support the cell's structure, and participate in muscle contraction. Example: Actin proteins are involved in the formation of the contractile ring during cell division.

Intermediate Filaments

Intermediate filaments are larger than microfilaments, with a diameter of \(8-12\) nm. They are composed of several different proteins, depending on the cell type. Their primary function is to provide mechanical strength to cells and maintain their shape. They also help maintain the positions of organelles within the cell. Example: Keratin, which is found in hair and nails, is an intermediate filament protein.

Microtubules

Microtubules are the largest of the cytoskeleton fibers, with a diameter of about \(25\) nm. They are composed of tubulin proteins, which bind together to form long tubes. Their main functions are to support the overall structure of the cell, maintain cell shape, and act as tracks for organelle movement and chromosome segregation during cell division. Example: Microtubules form the mitotic spindle during cell division, enabling the movement of chromosomes to opposite sides of the cell.

Function of the Cytoskeleton

In summary, the cytoskeleton plays a crucial role in maintaining cellular structure, providing mechanical support, facilitating cell movement, and organizing the internal components of the cell. Each type of protein fiber contributes to these functions through their unique structural and compositional properties.