The cytoskeleton of a cell is comprised of which of the following macromolecules?
A.
Carbohydrates
B.
Nucleic acids
C.
Lipids
D.
Proteins
The Correct Answer and Explanation is:
The cytoskeleton of a cell is primarily comprised of D. Proteins.
Explanation:
The cytoskeleton is a dynamic network of protein filaments and tubules that provides structural support, facilitates cellular movement, and plays a crucial role in intracellular transport, cell division, and maintaining the cell’s shape. The primary macromolecules involved in the cytoskeleton are proteins. These proteins assemble into several types of filaments that have distinct functions within the cell.
- Microfilaments (Actin Filaments):
- Composition: Microfilaments are primarily composed of actin, a globular protein. Actin filaments are the thinnest components of the cytoskeleton and are involved in various cellular processes, including muscle contraction, cell motility, and cell division.
- Function: Actin filaments form a dense network beneath the plasma membrane, providing mechanical support and aiding in cell shape maintenance. They are also essential for processes such as pseudopodia formation during cell movement and cytokinesis during cell division.
- Intermediate Filaments:
- Composition: Intermediate filaments are composed of various proteins depending on the cell type. Common proteins include keratins (in epithelial cells), vimentin (in connective tissue cells), and neurofilaments (in neurons).
- Function: These filaments provide structural stability and resilience to the cell. They help maintain cell shape and integrity by anchoring organelles in place and are crucial for withstanding mechanical stress.
- Microtubules:
- Composition: Microtubules are made of tubulin proteins, which assemble into hollow tubes. The main types of tubulin are alpha-tubulin and beta-tubulin.
- Function: Microtubules are involved in maintaining cell shape, facilitating intracellular transport (through motor proteins like kinesin and dynein), and organizing the mitotic spindle during cell division. They are also critical for the proper functioning of cilia and flagella.
The other macromolecules listed—carbohydrates, nucleic acids, and lipids—play different roles in the cell. Carbohydrates are involved in energy storage and cellular recognition, nucleic acids (DNA and RNA) are critical for genetic information and protein synthesis, and lipids are fundamental components of cell membranes. While these macromolecules are essential for overall cellular function, they do not form the structural framework of the cytoskeleton. Thus, proteins are the primary macromolecules that make up the cytoskeleton.