Interphase
Interphase is the longest phase of the cell cycle. It’s divided into three phases
G1 phase (cell growth), S phase (DNA replication), and G2 phase (preparation
for mitosis). In G1 cells do most of their growing. In this phase cell create their
new organelles. The G in G1 and G2 stand for “gap,” but the G1 and G2 phases
are actually periods of intense growth and activity.
The S phase is after the G1, during this phase new DNA is synthesized. The S
stand for synthesis, the cell at the end of S phase has a twice as much DNA as
it did at the beginning of the phase.
The G2 phase happens when the DNA replication is completed. The G2 phase
is the shortest of the three phases of the Interphase. During G2 many of the
organelles and molecules required for cell division. When the events of the
G2 are completed, the cell is ready to enter the M phase and begin the
process of the cell division.
Prophase
Prophase is the first phase of mitosis, prophase, is usually the longest and
may take the up to the half of the total time required to complete mitosis.
During prophase, DNA packs up and turns into chromosomes that become
visible. The centriole move to opposite sides of the nucleus and help organize
the spindle. The spindle fibers appear and the chromosomes are attached at
a point called centromere. The nucleus disappears and the nuclear envelops
breaks down.
Metaphase
Metaphase is the second phase in mitosis, is generally the shortest phase
during mitosis. During metaphase, chromosomes line up across the middle of
the cell. The spindle fibers connect to the centromere of each chromosome
to the two poles of the spindle.
Anaphase
Anaphase is the third phase in mitosis, anaphase begins when chromosomes
separate and begin to move apart. When anaphase begins, each part of the
chromosome is considered an individual chromosome. During anaphase, the
chromosomes separate and move along the spindle fibers to the opposite
sides of the cell. Anaphase comes to an end when this movement’s stop and
the chromosomes are completely separated into two groups.
Telophase
Following Anaphase is telophase, the fourth and final phase of mitosis.
During telophase, the chromosomes, which were distinct and condensed,
begin to spread and it becomes DNA once again. The nuclear envelope
reforms around each of the two groups of chromosomes. The spindle fibers
begin to break down, and a nucleolus becomes visible inside each nuclear
envelops. Mitosis is complete, however, there’s still one more step,
cytokinesis.
Cytokinesis
As a result of mitosis, two nuclei are formed each with a set of chromosomes.
All that remains of the M phase is cytokinesis, the division of cytoplasm itself.
Cytokinesis is after telophase or it can also occur at the same time.
Cytokinesis is different in plant and animal cells.
In animal cells, during cytokinesis, the cell membrane is drawn inward until
the cytoplasm is separated 50-50 for each one of the daughter cells. The two
daughter cells separate. Each daughter cell has a nucleus and the same
number of organelles.
In plant cells, cytokinesis runs in a different way. The cell membrane can’t
draw inward because the cell wall surrounding the cell membrane is too rigid.
Instead a structure called the cell plate forms a halfway between the two
nuclei. The cell plate turns into cell membranes that separate the two
daughter cells. The a cell wall forms in between the two membranes,
completing the process