Cell Division and Genetic Variation

This assignment provides an in-depth explanation of cell division, covering both mitosis and meiosis. It also explores genetic variation, discussing sources such as DNA mutation, gene duplication, and gene flow. The report concludes by highlighting the importance of understanding these concepts in biology. With references to relevant books and journals, this summary aims to provide a comprehensive overview of the assignment's content.

Cell Division and Heredity

Table of Contents
INTRODUCTION...........................................................................................................................3
MAIN BODY...................................................................................................................................3
Description of mitosis and meiosis along with discussing their significance.............................3
Impact of one geneticist on an understanding of genetics..........................................................7
Understanding of mono hybrid and dihybrid crosses including sex links..................................7
Main sources of variation including crossing over, gene and chromosome mutations..............8
CONCLUSION................................................................................................................................9
REFERENCES..............................................................................................................................10

INTRODUCTION
Cell division refers to a particular process in which a parent cell divides in order to give
rise to two of more daughter cells. It can be considered as an important biological process in
many organisms which is the means used by multicellular organisms to, replenish (repair), grow
and reproduce (Şen, Öztekin and Demirdöğen, 2018). The present report will focus on
description of mitosis and meiosis along with their significance. It will also include impact of
one geneticist on the understanding of genetics. The understanding of mono hybrid & dihybrid
crosses including sex links along with main sources of variation involving crossing over, gene
and chromosome mutations is given below.
MAIN BODY
Description of mitosis and meiosis along with discussing their significance
The mitosis can be described as a process of cell division in which a single cell divides
into two identical daughter cells. It involves the major purpose of mitosis is known as growth as
well as replacement of worn out cells from the body. However, the daughter cells formed by
mitosis are similar to mother cells size, shape and chromosome complement. In addition to this,

it has been analysed that if not corrected on time then mistakes occur during process of mitosis
may results into modification in genetic material i.e. DNA which can potentially results into
leads to different kinds of genetic disorders in an individual. The process of mitosis consists
number of phases such as interphase, prophase, metaphase, anaphase and telophase.
Interphase – This phases involves that preparation of cell division take place by copying
DNA in cell which leads to an identical set of chromosomes. It includes that the microtubules
extend from centrioles in pair of centrosomes outside the nucleus (Hlavová, Vítová and Bišová,
2016).
Prophase – In this phase, the chromosomes are observed to be condense in structure of X
shaped which is easily visible under microscope and every chromosome has two sister
chromatids having identical genetic data. The membrane around the nucleus get dissolved in cell
by releasing chromosomes and mitotic spindle consisting microtubules extends across cell
among centrioles.
Metaphase – This phase consist the line up of chromosomes from end-to-end along with
centre of the cell and centrioles are situated at opposite poles with mitotic spindle extending from
them. Moreover, the mitotic spindle fibres connect to each of sister chromatids.
Anaphase – The sister chromatids are pulled part by mitotic spindle ad both pulls to
opposite poles.

(Source: What is Mitosis, 2017)
Telophase – In this phase, set of chromosomes gather together and membrane formation
occur around the same in order to develop two fresh nuclei. It involves the separation of each
daughter cells with nucleus and a fill set of chromosomes then this procedures is known as
cytokinesis (Haque and Ghosh, 2017).
Significance of mitosis
Mitosis is significant as it facilitate development of zygote into adult organism for
reproduction. It is important for normal growth & development of living organisms and mitosis
is facilitate formation of new parts in plants including leaves, stems, roots and branches in order
Illustration 1: What is Mitosis?

repair them. Moreover, it is also helpful in production of new identical progeny in certain crops
such as sweet potato, potato, sugar cane etc. as it facilitate asexual reproduction.
Meiosis can be explained as a process of cell division in which a single cell divides twice
to produce four cells that consist half of original genetic information. This division is applicable
for sex cells i.e. sperm in males and egg in females. The daughter cells are haploid and meiosis
can be divided into nine stages which take place in Meiosis I and Meiosis II.
Meiosis I
Interphase – The DNA get copied in cell and microtubules extend from the centrosomes
consisting pair of chromosomes outside of the nucleus.
Prophase I – In this stage, chromosome get coiled & condense and the pairs of
chromosomes may exchange bits of DNA in procedure of crossing over & recombination
(Švorcová, 2016).
Metaphase I – This phase consist that chromosomes align along with the equator of the
cell and the homologous pair of chromosomes line up parallel to one another.
Anaphase I – The homologous chromosomes are moved to opposite ends of the cell in
cell division.
Telophase I & cytokinesis – The formation of nucleus take place and chromosomes may
uncoil hence, the separation of daughter cells is called cytokinesis.
Meiosis II
Prophase II – The chromosome attach in order to reform spindle apparatus and
duplication of centrioles.
Metaphase II – This phase consist that chromosomes moved to the equator of cell and
meiotic spindle fibres linked to sister chromatids.
Anaphase II – The chromosomes divides and every chromatid moves towards the
opposite poles of the cell.
Telophase II & cytokinesis – At this stage, chromosomes become uncoiled and
development of nuclear envelop begins.

(Source: What is meiosis, 2016)
Illustration 2: What is meiosis?

Significance of meiosis
Meiosis is significant in development of gametes which is necessary for sexual
reproduction. However, it provide support to maintain chromosome number in those organism
which are sexually reproduced. In addition to this, it will facilitate assortment chromosomes
which cause reshuffling of chromosomes and trails are controlled by them. Moreover, meiosis
also helps in crossing over to generate new combination of traits and variations.
Impact of one geneticist on an understanding of genetics
Genetics can be described as branch of science in which study of heredity is studied that
how characteristics of living things are transmitted to one generation to another. It involves the
study of genes, genetic variations and heredity in living organisms. According to analysis of pea
plant by Johann Gregor Mendel, the father of genetics discovered the fundamental laws of
inheritance.
The Law of Segregation – This consist that inherited trait can be defined by a gene pair
and parental genes are randomly separated to sex cells as these contains only one gene of the
pair. However, one genetics allele can be inherited from each parent to offspring after
fertilisation (Wild and Matos, 2016).
The Law of Independent Assortment – As per this law, genes of different traits are
sorted separately from one another as the inheritance of single character is independent from
inheritance of another gene.
The Law of Dominance – The law of dominance states that the dominant form is
expressed in an organism with an alternate forms of gene.
Understanding of mono hybrid and dihybrid crosses including sex links
The mono hybrid cross can be explained as a kind of genetic mix among two persons
which consists homozygous genotypes or those genotypes which have completely dominant or
completely recessive alleles. Basically the mono hybrid cross consist the phenomenon in which
hybridisation take place between two species that only has different of a single gene. However, it
leads to an opposite phenotypes in context of a specific character respectively. It has been
analysed that mono hybrid crosses are utilised by geneticists in order to determine way of
expression of heterozygous genotype of offspring having homozygous individuals while they
inherit from their parents. In addition to this, it is evaluated that this mix facilitate identification
of the dominant genotypes and mono hybrid cross is also has ability to signify about genetic mix

between two individuals with having heterozygous genotypes as such crosses facilitate
confirmation of regarding the dominance of an allele.
At the other hand, dihybrid cross can be explained as mating of two organisms that are
consisting identically hybrid for two traits. It can be considered as an experiment in genetics in
which phenotypes of two genes are followed through mating of individuals carrying multiple
alleles at those gene loci. However, it has been determined that most of organisms that produced
sexually generally carries two copies of each gene along with allowing them in order to carry
two differentiated alleles accordingly. In addition to this, the dihybrid cross includes parents
organisms having different pair of alleles in order to analyse regarding each trait. Moreover, it
consist that one parent has homozygous dominant allele whereas another possesses homozygous
recessive alleles. The resulting progeny has a hybrid genotype and express a dominant phenotype
respectively.
Main sources of variation including crossing over, gene and chromosome mutations
The genetic variations can be described as a measure of the variation that exists in genetic
make up of individuals within population. It can be considered as an effective and important
force in evolution because its is responsible for allowing phenomena of natural selection in order
to boost up or reduce frequency of alleles in the population (Threadgold, 2017). However, it can
be caused due to number of sources which are responsible for facilitating genetic variation in
living organisms. In addition to this, the phenomena of genetic variation of an entire species is
often known as genetic diversity. The genetic variation can be considered as differences in DNA
segment or genes in individuals in which each variation of gene is known as an allele. Moreover,
it has been analysed that genetic variation is important in respect of natural selection as it
consists the criteria of increase and decrease in frequency of alleles that already exist in the
overall population accordingly.
At the other hand, it has been determine that the phenomena of genetic variation take
place due to number of reasons mutations, random mating between organisms, random mating
and crossing over (or recombinant) among chromatids at the time of meiosis of homologous
chromosomes. Meanwhile, there are several sources of genetic variations such as mutation of
genes & chromosomes and gene duplication that are responsible for developing fresh alleles &
genes and boost up the genetic variation. In addition to this, it has been analysed that overall
sources for facilitating genetic variation that consist alteration in position or number of genes,

rapid reproduction, formation of new alleles and sexual reproduction accordingly. However, the
DNA mutation causes alteration of genes of individuals in population which results into genetic
variation. Moreover, the other source is gene flow which is responsible for differences in genetic
material with differentiated combinations of genes migrate to the population. Aprt from this, the
sexual reproduction facilitate promotion of variable gene combinations in particular population
that leads to a kind of genetic variation.
CONCLUSION
The above report has been concluded that cell division can be described as the process of
division of mother cell to give rise to two new daughter cells. However, it includes two types of
cell division like mitosis and meiosis having their own phases of cell division. Moreover, it
involves understanding of genetics through genetic laws like The Law of Segregation, The Law
of Independent Assortment and The Law of Dominance.

REFERENCES
Books and journals
Şen, M., Öztekin, C. and Demirdöğen, B., 2018. Impact of content knowledge on pedagogical
content knowledge in the context of cell division. Journal of Science Teacher
Education, 29(2), pp.102-127.
Hlavová, M., Vítová, M. and Bišová, K., 2016. Synchronization of green algae by light and dark
regimes for cell cycle and cell division studies. In Plant Cell Division (pp. 3-16).
Humana Press, New York, NY.
Haque, S.M. and Ghosh, B., 2017. Cell division study in ‘pollen mother cells’ and ‘pollen
grains’ of in vivo and ex vitro plants in Drimiopsis botryoides. Grana, 56(2), pp.124-
136.
Švorcová, J., 2016. Distributed heredity and development: a heterarchical
perspective. Biosemiotics, 9(3), pp.331-343.
Wild, P. and Matos, J., 2016. Cell cycle control of DNA joint molecule resolution. Current
opinion in cell biology, 40, pp.74-80.
Threadgold, L.T., 2017. The ultrastructure of the animal cell: international series in pure and
applied biology (Vol. 55). Elsevier.
Online
What is Mitosis. 2017. [Online]. Available through:<https://www.yourgenome.org/facts/what-is-
mitosis>
What is meiosis. 2016. [Online]. Available through:<https://www.yourgenome.org/facts/what-is-
meiosis>