The strands of microtubules are made up of which sub-units?

The strands of microtubules are made up of protein sub-units called tubulin, specifically alpha-tubulin and beta-tubulin dimers. These dimers assemble to form protofilaments, which together create the hollow cylindrical structure of microtubules.

Microtubules are cylindrical structures found in the cytoskeleton of eukaryotic cells. They play a crucial role in maintaining the cell's shape, enabling cell movement, and facilitating the transport of materials within the cell. They are also essential for important processes like cell division.

The strands of microtubules are made up of protein sub-units called tubulin. Each tubulin molecule is a dimer, which means it consists of two closely associated protein units: alpha-tubulin (α-tubulin) and beta-tubulin (β-tubulin). These dimers repeatedly join together to form long chains known as protofilaments.

A typical microtubule consists of 13 protofilaments arranged in a hollow, tube-like structure. As more alpha- and beta-tubulin dimers are added to the growing ends of the protofilaments, the microtubule elongates and functions as part of the cell's internal framework.

Tubulin sub-units can also assemble and disassemble rapidly, allowing microtubules to grow or shrink as needed. This dynamic nature is important for various cellular activities such as mitosis, intracellular transport, and the movement of cilia and flagella.