Your body uses the process called MITOSIS to make new, identical cells to replace those that are lost
or damaged.
Mitosis is a type of cell division that occurs in somatic
cells or body cells. The purpose of mitosis is to make diploid cells or copies
of the same cell. They are identical daughter cells, which are also identical
to its parent cell.
Interphase is the first step to cell division. It is the
longest stage in the cell division cycle. It is at this time where the cell
prepares itself for division. At this point, the cell is copying the DNA strand
of a chromosome it is meant to produce. The cell grows and stores energy, and
at the same time, it starts to replicate the organelles of the cell it will
produce.
Describe the four steps of mitosis:
Prophase: The nuclear envelope breaks down at this stage and
the centriole divides into two. Each centriole will go to the opposite sides of
the cell and start to form spindle. You can see the chromosomes under a light
microscope and you will see them assume the X-shape. The X-shape are two sister
chromatids that are joined at the middle.
Metaphase: It is at this stage where the chromosomes line up
along the middle of the cell. Spindles start to attach to the centromere of the
lined-up chromosomes, preparing to split them.
Anaphase: Chromosomes start to split up at the centromere. The
sister chromatids are pulled apart and brought to the opposite ends of the
cell. The chromatids then become separate chromosomes. As the spindle fibers
pull on the chromatids, they shorten. The chromatids form a V-shape.
Telophase: The nuclei start to form for each cell. At this
point, you can no longer see the chromosomes because they are enveloped already
within the nucleus.
Cytokinesis occurs at the end of cell division. It is the
physical division of the cells, as they separate into two different cells. The
cytoplasm splits into two, organelles distributed and the nucleus of each new
cell is already distinct.
Parent cells are the cells that go through cell division to
produce daughter cells. The information or the genetic material that make up
the parent cell will be passed on to the daughter cells. In mitosis, the
daughter cells will be identical to the parent cells, whilst in meiosis, the
daughter cells will get its information or traits from both mother and father.
Gametes are sex cells. These are mature haploid germ cells
(male or female) which unite with the opposite sex through sexual reproduction.
This union forms a zygote. The male gamete is more commonly known as sperm
cells, while the female gamete are called egg cells.
A HAPLOID is a
cell containing two complete sets of chromosomes, one from each parent.
MEIOSIS divides a
cell into four new daughter cells, each with half as many chromosomes as the
parent cell.
Why does meiosis allow for the creation of organisms with
unique characteristics?
Cell division though meiosis creates unique characteristics
in an organism because unlike in mitosis, the daughter cells produced are not
identical to the parent cell or each other. The chromosomes formed in meiosis have
parts that are from the father and the mother, which also carry the traits of
each. This brings out the unique characteristics of the off-spring.
Describe each step of meiosis:
Meiosis I: Chromosomes are copied at this phase. They
condensed into more compact forms, similar to mitosis. The difference is that
instead of the chromosomes lined up in single file, the chromosomes line up two-by-two.
Now each group is called homologous chromosomes. These homologous chromosomes
are what separate, each carrying a pair from the father and the mother cell.
Meiosis II:
In meiosis II, the process is similar to mitosis. It splits
the already divided cells further into four cells. The result is that each
gamete will have two monovalent chromosomes. These cells are not identical to the parent
cell. They have part of each parent cell.
Haploid cell refers to a cell that has half the number of
chromosome as its parent cell. For example, if a parent cell starts with 46
chromosomes, the haploid cells have only 23 chromosomes.
Both Meiosis and Mitosis are a type of cell division that occurs
in eukaryotic cells. They produce daughter cells. Those are mainly the similarities
of the two. As for the differences between the two, there are several that can
be pointed out.
In Mitosis, the number of daughter cells made is 2 and they
are identical. These daughter cells are called diploid. They go through only 1
nuclear division and it occurs in somatic cells. The main function of mitosis for
growth and asexual reproduction.
In Meiosis, the number of daughter cells made is 4 and they
are not identical. These daughter cells are called haploid. They go through 2 nuclear
divisions and they occur in the gonads. The main function of meiosis is to
produce sex cells.
