BIOLOGY 1010
Mitosis in the Cell
By
Kody Lundell
4/25/2012
Mitosis in the Cell
Reflection
In writing this paper I gained a better understanding of each step of mitosis and how it
affects me. I thought that it would be extremely difficult to write an essay about anything in
biology but it was actually pretty fun. I never realized how much information there is about
mitosis. I feel that mitosis is one of the many reasons that I am around today. I feel that my very
existence depends on mitosis. I am amazed to see that they have been studying mitosis for over
100 years. This was a very educative paper.
1
Mitosis in the Cell
All cells are the basic unit of life. All living things have cells. Cell mitosis takes places in
different stages. These stages are prophase, prometaphase, metaphase, anaphase, and telophase
(writework.com “Mitosis & Meiosis of Eukaryotic Organisms”, Feb, 01, 2008). This paper
explores those different stages to help better understand mitosis. There is always the journey
through the history of mitosis and how it contributes to human health. Functions of the phases of
mitosis will be provided along with their names. All of these stages play a pretty huge
role in the process and events of cell growth and development. Animal cells are one of the most
dramatic shapes a cell will ever experience
(www.ucl.ac.uk/lmcb/research-group/buzz-baum-research-group).
Mitosis is a nuclear division that gives the result of two new nuclei. Each of the new
nuclei will have the same number of chromosomes as the original nucleus. The original cell, the
parent cell, is the cell that divides and the new resulting cells are then called daughter cells. At
the beginning of cell division the chromatin start to condense and is compacted into a visible
form that is rodlike. That rodlike form are the sister chromatids that are held together at the
centromere (Mader continues in Mitosis Phases, p. 93).
Mitosis was first discovered by Walther Flemming in the early 1880’s in which the word
mitosis comes from the Greek word meaning thread. They had been arguing because some
people could see the microfibers but others couldn’t see the microfibers. It was not until Shinya
Inoue decided to use polarized microscopy that confirmed the existence of birefringement
spindle fibers in living cells. The fixative glutaraldehyde came out and made it a whole lot easier
for scientists to see microtubules in the electron microscope (Asbury and Wordeman state in
“Short History of Mitosis: the Early Days”).
In both animal cells and plant cells alike, a spindle apparatus is involved in the process of
Mitosis. A spindle apparatus is composed of microtubules organized into spindle fibers of two
2
Mitosis in the Cell
types. These two types are kinetochore fibers and polar fibers. Kinetochores moving along
kinetochore fibers pull daughter chromosomes apart. Polar fibers slide pushing the poles and
daughter chromosomes apart. The spindle takes over and takes up the entire cell because the
nuclear envelope has fragmented. (Mader has expressed her views “Concepts of Biology, Second
edition, Mitosis Maintains Chromosome number, p. 147”).
Now onto the phases of mitosis. There are 5 stages altogether in mitosis. These stages
include prophase, prometaphase, metaphase, anaphase, and telophase. These phases are part of
the cell division process. Mitosis is a type of duplication division. It is called that because the
nuclei of two new daughter cells have the same number and kinds of chromosomes as the cell
parent that divides (Mader has expressed her views “Concepts of Biology, Second edition,
Mitosis Maintains Chromosome number, p. 146”).
A centrosome is the microtubule organizing center of the cell. The daughter centrosomes
have the ability to produce the spindle fibers of the spindle apparatus. The spindle apparatus
assists in the separation of the chromatids as they are moving towards the opposite poles of the
spindle. It is considered daughter chromosomes as soon as the chromatids separate from one
another Mader has expressed her views “Concepts of Biology, Second edition,
Mitosis Maintains Chromosome number, p. 146”).
During the first phase, prophase, in mitosis the nucleolus fades and the chromatin
condenses into chromosomes. The replicated chromosome is comprised of two chromatids. Both
of the chromatids have the same genetic information as each other. The microtubules of the
cytoskeleton, which are responsible for cell shape, motility and attachment to other cells, begin
to disassemble. The microtubules then act as building blocks as they are used to grow the mitotic
spindle from the region of the centromeres (www.cellsalive.com/mitosis.htm). Duplicated
chromosomes are now visible. Centromeres now begin moving apart, and spindle also begins to
form (Mader continues in Mitosis Phases, p. 93).
3
Mitosis in the Cell
During the second phase, which is prometaphase, the nucleus in no longer recognizable
due to that the nuclear envelope is broken down. Some of the mitotic spindle fibers are elongated
from the centromeres and attached to kinetochores. Protein begins to bundle at the centromere
region on the chromosomes where the sister chromatids are joined. Other spindle fibers elongate
and begin to overlap each other at the cell center instead of attaching to other chromosomes
(www.cellsalive.com/mitosis.htm). The kinetochore of each chromatid is attached to a spindle
fiber. Some spindle fibers stretch from each spindle pole (Mader continues in Mitosis Phases, p.
93).
During the third phase, metaphase, tension is applied by the spindle fibers. This tension
aligns all of the chromosomes in one plane. They a miraculously all aligned in the center of the
cell due to the tension (www.cellsalive.com/mitosis.htm). Centromeres of duplicated
chromosomes are aligned at the metaphase plate. The metaphase plate is the center of the fully
formed spindle. Kinetochores attached to spindle sister chromatids fibers that come from the
opposite spindle poles (Mader continues in Mitosis Phases, p. 93).
During the fourth phase, anaphase, the spindle fibers are shortened. Also the kinetochores
are separated. The chromatids, daughter chromosomes, begin moving toward the cell poles as
they are pulled apart (www.cellsalive.com/mitosis.htm). Sister chromatids part and become
daughter chromosomes that move toward the spindle poles. Each pole receives the same number
and kinds of chromosomes as the parent cell (Mader continues in Mitosis Phases, p. 93).
During the fifth phase, telophase, the daughter chromosomes have arrived at the poles
and the spindle fibers that have pulled them apart begin to disappear
(www.cellsalive.com/mitosis.htm). Daughter cells are forming as nuclear envelopes and nucleoli
reappear. Chromosomes will become indistinct chromatin (Mader continues in Mitosis Phases, p.
93).
Mitosis contributes to human health because it permits growth and repair. When a
4
Mitosis in the Cell
fertilized egg develops into a newborn baby it is called mitosis. Mitosis is also after birth when
the child becomes an adult. Mitosis is what allows cuts to heal and broken bones to mend as you
go throughout life. Mitosis is what allows adult stem cells to re-supply the body with specialized
cells. Mitosis forms new skin cells to replace the skin cells that are continually shed from the
surface of the body (Mader has expressed her views “Concepts of Biology, Second edition,
Mitosis has a set series of phases, p. 149”).
In conclusion this paper explains how important mitosis is in everyday life. Mitosis gets
more and more exciting each and every day. It is surprising to see how organized mitosis is with
prophase, prometaphase, metaphase, anaphase, and telophase. The function and history of
mitosis has been explored and contribution to human health has been made. Without Mitosis
humans or animals wouldn’t be able to function or exist.
5
Mitosis in the Cell
References
Mader has expressed her views (“Concepts of Biology, Second edition, Mitosis Maintains
Chromosome number, p. 147”).
((www.ucl.ac.uk/lmcb/research-group/buzz-baum-research-groupwritework.com)
“Mitosis & Meiosis of Eukaryotic Organisms”(www.ucl.ac.uk/lmcb/research-group/buzz-baumresearch-group, 01, 2008).
(Asbury and Wordeman state in “Short History of Mitosis: the Early Days”).
(www.cellsalive.com/mitosis.htm).
6