Question

Which one of the following statements regarding mitosis is true?

Sister chromatids are held together by condensins from the time they arise by DNA replication until the time they separate at anaphase.
-Cohesins are required to make the chromosomes more compact and thus to prevent tangling between different chromosomes.
-The mitotic spindle is composed of actin filaments and myosin filaments.
-Microtubule-dependent motor proteins and microtubule polymerization and depolymerization are mainly responsible for the organized movements of chromosomes during mitosis.
-The centromere nucleates a radial array of microtubules called an aster, and its duplication is triggered by S-Cdk.

Answer 1

The correct statement about mitosis is that microtubule-dependent motor proteins and the dynamic nature of microtubules facilitate the orderly movement of chromosomes during mitosis. Cohesins and condensins play roles in holding chromatids together and condensation respectively, while the mitotic spindle is composed of microtubules, not actin and myosin.

Step-by-step explanation:

The true statement regarding mitosis is: Microtubule-dependent motor proteins and microtubule polymerization and depolymerization are mainly responsible for the organized movements of chromosomes during mitosis.

Throughout mitosis, sister chromatids are held together by cohesin proteins until they are separated during anaphase. On the other hand, condensins are involved in the condensation and coiling of sister chromatids, making them compact and visible under a microscope.

The mitotic spindle is not made up of actin and myosin filaments, as suggested by one of the statements, but is instead composed of microtubules that interact with kinetochores attached to centromeres of the sister chromatids. These spindles facilitate the movement of sister chromatids towards opposite poles. Additionally, the centromere does not nucleate asters but is crucial for kinetochore formation and chromosome attachment to the spindle fibers.