TABLE 2
READING ACTIVITY COMPARING
MITOSIS AND MEIOSIS
Contents
1 Process Differences
1.1 Different Stages of Mitosis and
Meiosis
2 Differences in Purpose
2.1 Significance
3 Occurrence
4 History
5 Evolution
6 Chromosomal pattern comparison
7 Videos explaining the difference
Process Differences
Mitosis is a method of reproduction for single celled organisms that reproduce asexually.
An identical version of the organism is created through splitting of the cell in two. Meiosis may
result in millions of spermazoa and egg cells with unique genetic patterns. The mating of the two
cells formed by meiosis results in a unique genetic offspring of the same species. Meiosis is a
major factor in evolution, natural selection, and biodiversity. The processes of cellular division
shown in mitosis and meiosis are present in all manner of life forms including humans, animals,
plants, fungi, and single celled organisms and species. Essentially any cell based organism of
which all organic life is based will exhibit some form of
mitosis and meiosis for growth and reproduction of the
individual and species.
Cell division is the process by which a multicellular
organism grows, repairs, maintains and reproduces itself.
Most cells have a nucleus which is the controlling centre
directing a cells activity. The instructions for these activities
are contained in the chromosomes, which are composed of
proteins and DNA. DNA contains the coded chemical
instructions, which direct the growth, differentiation and
functioning of a cell.
Mitosis is a type of cell division that results in the production of daughter cells, which are
identical to the original parent cell. It is referred to as division for growth and repair. Mitosis
occurs in all body cells. The number and type of chromosomes produced are exactly the same as
the original parent cell. The parent cell duplicates its DNA by duplicating the chromosomes, the
chromosomes then separate to either end of the cell and the cell eventually divides into two
daughter cells.
Meiosis is a type of cell division that forms cells with half the number of chromosomes normally
found in cells of the species. If they did not, on fertilization, the chromosome number would be
doubled in the new generation. Meiosis is referred to as division for reproduction. Chromosomes
can be matched into pairs, which are similar – homologous chromosomes. Each pair is made up
of one chromosome contributed by each parent and carries information about the same inherited
characteristics. During the process of meiosis, the homologous chromosomes are divided
between the separate gametes. In this way, meiosis produces haploid cells, which show variation.
This variation has been produced by the random segregation or assortment of chromosomes
pairs, or by crossing over where the chromosomes get tangled up when they separate.
Different Stages of Mitosis and Meiosis
The different phases of meiosis are: Prophase, Metaphase, Anaphase and Telophase.
An overview of the process and phases of meiosis
The stages of mitosis are: Interphase, Preprophase, Prophase, Prometaphase, Metaphase,
Anaphase, Telophase and Cytokinesis.
An overview of the process of mitosis.
Differences in Purpose
Both Meiosis and Mitosis are found in complex organisms which reproduce sexually. Mitosis
may be used for human growth, the replenishment of depleted organs and tissues, healing, and
sustenance of the body. Identical versions of cells can be created to form tissues through Mitosis.
Meiosis is a special process reserved for the creation of the egg and sperm cells. The same
patterns may be found in many species of plant and animal cell reproduction.
Significance
The importance of mitosis is the maintenance of the chromosomal set; each cell formed receives
chromosomes that are alike in composition and equal in number to the chromosomes of the
parent cell.
Occurrence
Meiosis is found to occur in humans, animals and plants while mitosis is found in single-cell
species as well.
History
Meiosis was discovered and described for the first time in sea urchin eggs in 1876, by noted
German biologist Oscar Hertwig.
Walther Flemming discovered the process of Mitosis in 1882.
Evolution
Mitosis as a form of reproduction for single-cell organisms originated with life itself (around 4
billion years ago). Meiosis is thought to have appeared 1.4 billion years ago.
Chromosomal pattern comparison
In mitosis, each daughter cell ends up with two complete sets of chromosomes while in meiosis,
each daughter cell ends up with one set of chromosomes.
Both mitosis and meiosis are studied by scientists generally by using a microscope to identify
and classify chromosomal patterns and relationships within the cell’s structure. An understanding
of the way cells synthesize chromosomes for reproduction can be applied in bio-machines and
nano-technology. Transplantation of genes and chromosomes through injection and implantation
is used to experiment with bio-engineering and cloning. Understanding the process through
which cells replicate also has application in medicine and the study of health and disease.
Videos explaining the difference
Here are two videos (the first one short and the second is longer, more in-depth) that
explain the process of mitosis and meiosis.
http://www.youtube.com/watch?v=sJCWVTnFf5o
http://www.youtube.com/watch?v=mr0oiws9ZvM