What Helps the Animal Cell Keep Its Structure?

Types

• There are three types of filaments in the cytoskeleton: intermediate filaments, which are the toughest and most durable, microtubules and microfilaments, which are the thinnest of the three. Each is made from different kinds of proteins. Microtubules are hollow straw-like structures assembled from sub-units of a protein called tubulin, while microfilaments are made from a protein called actin and intermediate filaments are made from a variety of fibrous proteins with similar characteristics.

Intermediate Filaments

• Intermediate filaments are like the cables or hawsers of the cell, providing the strength the cell needs to resist stretching. Intermediate filaments in your skin cells are typically made from keratin, while intermediate filaments in muscle cells are generally made from vimentin or similar proteins. The inside of the nuclear membrane in your cells is also girded with a thick mesh of intermediate filaments called the nuclear lamina. The nuclear lamina are temporarily disassembled during cell division.

Microtubules

• Microtubules are much stiffer and less flexible than intermediate filaments, or microfilaments. If the intermediate filaments are like cables or ropes, then microtubules are more like hollow beams. They fulfill a remarkable variety of critical roles in maintenance of cell structure, cell division, muscle contraction, movement of cilia and cell organization. Motor proteins actually transport cargo and organelles along microtubules, using them as a kind of walkway to carry needed items to various parts of the cell.

Microfilaments

• Actin or microfilaments are the thinnest and most flexible of the three major types, but their small size belies their importance, because just like the others they play myriad useful roles. The cell cortex is a dense mesh of actin filaments just below the cell's membrane that supports the membrane and helps preserve the overall shape of the cell. Aside from their structural role, actin filaments are also essential for cell movement and muscle contraction.