The separation of two chromatids of each chromosome,which is observed in anaphase,is initiated by:

During mitosis,$ER$,nucleolus,and other cell organelles begin to disappear at

Select the correct statement regarding $S-$phase of interphase.
$I.$ Occurs between $G_1$ and $G_2$ phase.
$II.$ $DNA$ replication begins in the nucleus.
$III.$ Centrioles duplicate in the cytoplasm.
$IV.$ As $DNA$ is doubled,the number of chromosomes also doubles.

Which of the following events is associated with the formation of the nuclear envelope during the $M$ phase of the cell cycle?

Anaphase Promoting Complex $(APC)$ is a protein degradation machinery necessary for proper mitosis of animal cell. If $APC$ is defective in a human cell,which of the following is expected to occur?

During metaphase,chromosomes are attached to spindle fibers by which of the following structures?