Final answer:
Microfilaments, composed of intertwined actin strands, are the shortest elements of the cytoskeleton, positioned just beneath the plasma membrane, and are highly crosslinked to support cell shape and enable cellular movement, especially during cytokinesis.
Step-by-step explanation:
The type of cytoskeleton that is shorter, closely situated to the plasma membrane (PM), and highly crosslinked is the microfilament. Microfilaments are the narrowest elements of the cytoskeleton and consist of two intertwined strands of a globular protein known as actin. They are typically found in the cortex of cells, just beneath the plasma membrane, where they play a crucial role in maintaining cell shape, supporting cellular structures like microvilli, and facilitating cell movement through dynamic reorganization.
These actin filaments are essential for processes such as cytokinesis during cell division, where they facilitate the creation of a cleavage furrow to divide the cell. Additionally, in non-muscle cells, microfilaments interact with non-muscle myosin to enable movements such as cell contraction and pinching during division. Their ability to rapidly assemble and disassemble allows for the dynamic reconfiguration of the cell's shape and movement.