Final answer:
The statement is true; microtubule-dependent motor proteins along with microtubule dynamics are essential for chromosome movement during mitosis. Motor proteins like dynein and kinesin use ATP to move chromosomes along microtubule tracks formed by the polymerization and depolymerization of tubulin dimers.
Step-by-step explanation:
The statement that microtubule-dependent motor proteins and microtubule polymerization and depolymerization are mainly responsible for the organized movements of chromosomes during mitosis is true. Microtubules, composed of α-tubulin and β-tubulin dimers, are essential components of the cytoskeleton—structures that maintain cell shape, enable cellular movement, and are critical during cell division. During mitosis, microtubules form the mitotic spindle, originating from centrosomes that organize these microtubules.
Motor proteins such as dynein and kinesin play crucial roles in the dynamics of mitosis. They utilize ATP hydrolysis to move chromosomes along the microtubule tracks. For example, dynein motors attached to microtubules aid in pulling chromatids apart to opposite poles of the cell, a key part of the chromosomal segregation that ensures each daughter cell receives the correct number of chromosomes.
Polar microtubules, another component of the mitotic spindle, do not attach to chromosomes but instead overlap at the center of the cell, assisting in cell elongation during mitosis. The pushing and pulling forces generated by these microtubules and their dynamic instability—continuous assembly and disassembly of tubulin subunits—are essential for the movements of chromosomes during various stages of mitosis, such as prometaphase and anaphase.