Test: Cytoskeleton - 1 - MCAT MCQ

The cytoskeleton is composed of three main components: microtubules, microfilaments (also known as actin filaments), and intermediate filaments. Mitochondria, on the other hand, are organelles involved in energy production and are not part of the cytoskeleton.

Intermediate filaments provide mechanical support to cells and help maintain cell shape. They are particularly important in tissues subjected to mechanical stress, such as the skin and muscles.

Microtubules are made up of tubulin protein subunits. These hollow cylindrical structures provide structural support, serve as tracks for intracellular transport, and are involved in cell division and cell motility.

Microfilaments, or actin filaments, are responsible for muscle contraction. The interaction between actin and myosin proteins generates the force required for muscle contraction.

Microtubules play a crucial role in the formation and movement of cilia and flagella. They form the axoneme, the structural backbone of these cellular extensions, which allows for their motility.

The centrosome, located near the nucleus, plays a key role in the nucleation and organization of microtubules. It contains a pair of centrioles and serves as a microtubule-organizing center.

Microtubules serve as tracks for the movement of organelles and vesicles within the cell. Motor proteins, such as dynein and kinesin, utilize microtubules for intracellular transport.

Microfilaments, specifically actin filaments, are responsible for the formation of the cleavage furrow during cell division. They contract and pinch the cell membrane inward, eventually leading to cell separation.

Intermediate filaments play a role in providing structural support to the nuclear envelope, which surrounds the nucleus. They help maintain the shape and integrity of the nuclear membrane.

Microfilaments, or actin filaments, are involved in cell motility and the formation of cellular protrusions such as lamellipodia and filopodia. These structures enable cell movement and exploration of the environment.