Final answer:
The cytoskeleton comprises three main protein elements: microfilaments made of actin, intermediate filaments that include proteins like keratin, and microtubules composed of alpha and beta tubulin monomers. The correct answer is C) Actin, tubulin, and intermediate filaments.
Step-by-step explanation:
The Three Predominant Proteins of the Cytoskeleton
The cytoskeleton is made up of three primary types of protein fibers that contribute to cell structure and function. These are microfilaments (also known as actin filaments), intermediate filaments, and microtubules. Microfilaments are composed of actin, a globular protein that intertwines into strands, playing a crucial role in cellular movements. Intermediate filaments, such as keratin, are involved in maintaining cell integrity and anchoring cellular structures, including the nucleus. Microtubules are composed of α- and β-tubulin protein monomers, and they provide resistance to compression, serve as pathways for motor proteins, and facilitate chromosomal separation during cell division.
Based on this information, the correct answer to the question, "The three predominant proteins that make up a cytoskeleton," is C) Actin, tubulin, and intermediate filaments.