I. Mitosis or M Phase: Cell growth and protein production stop
at this stage in the cell cycle. All of
the cell's energy is focused on the complex and orderly division into two similar daughter cells. Mitosis
is much shorter than interphase, lasting perhaps only one to two hours. As in both G1 and G2, there
is a Checkpoint in the middle of mitosis (Metaphase Checkpoint) that ensures the cell is ready to
complete cell division.
II. Mitosis phases:
Prophase: During this first mitotic stage, 1.the nucleolus fades and chromatin (replicated DNA and
associated proteins) condenses into chromosomes. 2.Each replicated chromosome
comprises two chromatids, both with the same genetic information. 3.Microtubules of the
cytoskeleton, responsible for cell shape, motility and attachment to other cells during
Prometaphase: In this stage the 1.
envelope breaks down so there is no longer a recognizable
nucleus. 2.Some mitotic spindle fibers elongate from the centrioles and attach to
kinetichores, protein bundles located on the chromosomes.
Metaphase: Tension applied by the spindle
fibers aligns all chromosomes in one plane at the center
of the cell.
Anaphase: Spindle fibers shorten, the kinetichores
separate, and the chromatids (daughter
chromosomes) are pulled apart and begin moving to the cell poles.
Telophase: The daughter chromosomes arrive
at the poles and the spindle fibers that have pulled
them apart disappear.
Cytokinesis: The spindle fibers not attached
to chromosomes begin breaking down until only that
portion of overlap is left. It is in this region that a contractile ring cleaves the cell
into two daughter cells. Microtubules then reorganize into a new
cytoskeleton for the return to interphase.
III. Asexual Reproduction: