Question

The primary function of intermediate filament is-
A. Generate movement
B. Provide mechanical stability
C. Transport organelles within the cell
D. Stabilize microtubules against disassembly

Answer 1

Hint: Intermediate filaments are an important component of a cell's cytoskeletal system. Intermediate filaments are prominent in those cells that can withstand mechanical stress and these are the most insoluble part of the cell.

Complete answer: The cytoskeletal structural components that are found in the cells of vertebrates are called an intermediate filament.
There are three major cytoskeletal elements, intermediate filament is one of them.
The other two are microtubules and thin filaments. These three components function together to enhance cell shape, its structure, and organelle motility.
Intermediate filaments are stable and durable.
They are intermediate in size as compared to thin filaments and microtubules, having an 8-10 nm range of diameter. They can be dissociated by urea.

Additional information: Intermediate filaments are of five major types. They are-
1. Type I and II- These are acidic and basic keratins respectively. Keratins intermediate filaments are responsible for forming junctions that can hold cells together or attach cells to matrices.
2. Type III- This class includes proteins like vimentin and desmin. Vimentin is found in fibroblasts, smooth muscle cells, and white blood cells, while desmin can be found in muscle cells.
3. Type IV- This class includes three neurofilament proteins, namely NF-L, NF-M, and NF-H for light, medium, and heavy, respectively. They are abundantly present in the axons of motor neurons.
4. Type V- These proteins are nuclear lamins. They are present in most of the eukaryotic cells. These are important components of the nuclear envelope.
Intermediate filaments play the most important role in providing mechanical support to the plasma membrane where it comes into contact with other cells. On the contrary, microfilaments and microtubules are involved in cell motility.

So, the correct option is B.

Note: The major components of intermediate filaments are a variety of proteins that are expressed in different types of cells, whereas actin filaments and microtubules are nothing but polymers of single types of proteins.