1.Describe the three main types of cytoskeletal fibres that form the cytoskeleton.

The three main types of cytoskeletal fibers that form the cytoskeleton are microtubules, microfilaments, and intermediate filaments.

1. Microtubules: These are the largest of the cytoskeletal fibers with a diameter of about 25 nanometers. They are hollow tubes made up of protein subunits called tubulins. Microtubules are responsible for maintaining cell shape and structure, and they also play a crucial role in cell division by forming the mitotic spindle, which separates chromosomes.

2. Microfilaments: These are the smallest of the cytoskeletal fibers with a diameter of about 7 nanometers. They are composed of two intertwined strands of the protein actin. Microfilaments are involved in a variety of cellular functions including muscle contraction, cell motility, and cell division.

3. Intermediate Filaments: As the name suggests, these fibers are intermediate in size between microtubules and microfilaments, with a diameter of about 10 nanometers. They are composed of a variety of proteins, depending on the cell type. Intermediate filaments provide mechanical strength to cells and tissues, and they help to anchor organelles within the cell.