Genetic Materials and Mechanisms: DNA, Genes, Chromosomes, Mitosis, Meiosis

This report explains the structure of DNA, genes, and chromosomes, the mechanism and importance of DNA replication, events of mitosis and meiosis, comparison of the products of meiosis with mitosis, and the importance of meiosis in generation variation.

Task 22 Genetic Materials and
Mechanisms

TABLE OF CONTENTS
INTRODUCTION...........................................................................................................................3
MAIN BODY..................................................................................................................................3
1.1 Explaining the structure of DNA, genes and chromosomes..................................................3
1.2 Description of the mechanism and its importance of DNA replication.................................5
1.3 Explaining the events of mitosis and meiosis........................................................................7
1.4 Comparison of the products of meiosis with mitosis.............................................................8
1.5 Importance of meiosis in the generation variation................................................................9
CONCLUSION................................................................................................................................9
REFERENCES..............................................................................................................................10
Online........................................................................................................................................10

INTRODUCTION
Genetic mechanism involves the series of the gene expression that starts within the
production of the MRNA which is a transcription. It is followed by its procedure and the
localization and becomes continue in the protein synthesis (Xiao and et.al., 2021). Each of the
step under this is regulated towards controlling the gene expression which are required. The
present report will shed a light over the genetic materials and mechanism. The report will
highlight the structure of DNA, genes and chromosomes. Also, description of the mechanism and
importance of DNA replication will be done. Furthermore, events of mitosis and meiosis will be
described. Moreover, comparison of the products of meiosis with mitosis will be done. Lastly,
importance of meiosis in generation variation will be explained.
MAIN BODY
1.1 Explaining the structure of DNA, genes and chromosomes
Figure 1- Structure of DNA
(Source- DNA, Structure, functions and discovery, 2021)

DNA is a double helical structure which resembles a twisted ladder. It comprises
of two strands which wind around each other and form the double helix shape. Each strand is
made of alternate deoxyribose and phosphate groups. These are known as polynucleotides and
comprise of monomeric units called as nucleotides (Srivastava and et.al., 2020). In each of the
nucleotides, there is one of the four nitrogen containing nucleobases, namely guanine, thymine,
cytosine and adenine. Covalent bonds join the nucleotides to one another by forming linkage
between the sugar of one nucleotide and the phosphate of another. This leads to the formation of
an alternate sugar phosphate backbone.
Figure 2-Structure of Gene
(Source-Gene heredity, 2021)
Gene are mainly composed of the deoxyribonucleic acid (DNA) which are aligned with
the genes consisting of the close related element which is known as ribonucleic acid (RNA).
Gene structure is the organization of the sequences compound within a gene. Genes mainly
contain the information which are necessary for the living organism in terms of surviving and

reproducing. Gene is transcribed from the DNA to RNA (Pervouchine, 2018). The DNA
molecule is composed with the two chains and these chains is of nuleotides which wind about
each other in regards to resemble the twisted ladder.
Figure 3-Structure of Chromosomes
(Source- Chromosomes, 2021)
Chromosome is concerned with the eight parts and those are- Centromere or
kineotochore, in this chromatids spindle fibres are attached. Chromatid, it is the half of those
chromosome which is joined. Chromatin, it is the complex of the DNA & proteins that leads to
form the chromosomes. Secondary constriction is present for the nuclear organization (Paulson
and et.al., 2021).
Telomere is referred as the terminal region of each side in chromosome. Chromomeres
are the bead like structure which are present over the threads and Matrix is the jelly like
substance which is present at the inside of the pellicile.
1.2 Description of the mechanism and its importance of DNA replication

Figure 4Model for DNA Replication
(Source- Molecular mechanism of DNA replication, 2022)

The basic mechanism of DNA replication is mainly similar across the organisms. DNA
replication takes place in the bacterium E. coli. However, the mechanism of the replication in
similar in the human beings and other eukaryotes. The mechanism of DNA replication involves
three models and those are- Semi-conservative, conservative and dispersive. The semi-
conservative model results in the two DNA molecules in which one of them is original strand
and one is new strand (Berti, Cortez and Lopes, 2020). Conservative replication is concerned of
both the original DNA strands. Dispersive replication results in the mixture of parental and
daughter DNA. The first mechanism is aligned with the use of the faithful polymerase enzyme
which accurately copies the long stretches of the DNA. The stem cells have the extra safeguard
in order to preserve the accuracy of their genetic information.
DNA replication is important process as wherever the cells divides it results is organizing
two new daughter cells which must contains the same genetic information and DNA as same as
the parent cell. The DNA replication process relies on the fact that each strand of DNA can lead
to serve as the template for the duplication (Krude, 2019). DNA replication and mechanism are
the critical process which ensure that the correct genetic material of the biological system is
being carried on. The DNA consistently undergoes the process of replication along with the
divisions. However, errors can often occur in this process.
1.3 Explaining the events of mitosis and meiosis
Events of mitosis
The basic events of the mitosis includes the chromosomes condensation, the formation of
the mitotic spindle and the attachment of the chromosomes to the spindle microtubules. The
events of mitosis are parted into phases and those are-
Prophase- It begins with this phase, in this the chromosomes recruits the condensin and
undergoes to it and the process will continue until the metaphase. During this phase the spindle
begins to form the two pairs of the centrioles which moves opposite to the poles and the
microtubules which often begins to polymerize from the duplicated centrosomes (Crane and
et.al., 2020).
Prometaphase- This phase has been determined as the dynamic part of the cell cycle. In this,
microtubules grows from the centrosomes. Promethaphase ensures that the chromosomes are

pulled and tugged in the opposite direction while microtubules grow from both the pole of
spindle.
Metaphase- In this it has been determined whether the spindle is properly assembled or not.
Anaphase- The two separate classes of the movement is being occur in this phase. The spindle
poles are separated as the microtubules moves past on each other.
Telophase- This is the end phase under which the chromosomes reach the poles. The daughter
cells that results from the process has the identical genetic composition in this phase (Clift and
Schuh, 2019).
Events of meiosis
As mitosis, meiosis often has the stages which are- prophase, metaphase, anaphase and
the telophase. However, the major key difference is that during the meiosis each of the phase
occurs twice. One phase occurs at the time when round of first division takes place and again it
occurs when the second round of the division takes place. Thus events of meiosis are concerned
with Meiosis I and Meiosis II (Matos and et.al., 2019).
1.4 Comparison of the products of meiosis with mitosis
The stages of events are same in the mitosis and meiosis. However, the phases in meiosis has
bene occurred twice. Here is the comparison of the product of mitosis with the meiosis.
Product of mitosis Product of meiosis
 It involves the two successive cells
division
 The result of this is in the four daughter
cells
 This provides the results in the haploid
daughter cells in which chromosomes
number is the half of the parent cell.
 In this, the daughter cells are
genetically different (Crickard and
Greene, 2018)
 It only occurs in the animals, fungi and
the plants.
 It creates the germ cells.
 It involves the diploid parent cell.
 It consists of the ineterphase,
metaphase, prophase and telophase but
twice time.
 In the metaphase II, there is individual
chromosomes which is the pair of the
chromatids and it line up along with the
equator.
 During the time of Anaphase II, the
sister chromatids is separated to their
opposite poles (Cahoon and Libuda,
2019).
 It ends with the cytokinesis.

 In the metaphase I, the pair of the
chromosomes is line-up with equator.
 In the Anaphase II, sister chromatids
moves together to the same pole.
1.5 Importance of meiosis in the generation variation
The generation variation has been increased by the meiosis. During the fertilisation, 1
gamete from each parent is combined and forms the Zygote and this becomes possible due to the
recombination of the independent assortment under the meiosis. Each of the gamete is concerned
with the different set of the DNA. Meiosis in the generation variation is important for the three
main reason and those are- it allows the sexual reproduction of the diploid organism, it helps in
enabling the genetic diversity and it repairs the genetic defects. Thus, these are the major reasons
that meiosis is important in the generation variation.
In Meiosis, variation has been occur as each of the gamete whether it is sperm or egg
contains the mixture of the denes from the two different parental chromosomes under the sexual
reproduction. Thus, genetic coupling of those DNA that are non-identical has been take place in
the meiosis (Riley and Law, 2020). The crossing over in the prophase I of the Meiosis I,
homologous chromosomes lines up the chromatids and the cross over or the exchange segments
that are corresponding of the DNA complies with each other. This leads to produce the genetic
variation within allowing the more of the combination of the genes that can be produced.
CONCLUSION
The above report has concluded that genetic material and mechanism goes from the various
stages. The structure of the DNA, gene and chromosomes are varied to each other. The
mechanism of DNA replication is concerned with the different models. The report has shown
that DNA replication is highly important as it is essential for managing the genetic community.
The report has highlighted the events of mitosis and meiosis. The comparison of the products of
meiosis with the mitosis in being done and the importance of meiosis in generation variation has
been described.

REFERENCES
Books and Journals
Berti, M., Cortez, D. and Lopes, M., 2020. The plasticity of DNA replication forks in response to
clinically relevant genotoxic stress. Nature reviews Molecular cell biology. 21(10).
pp.633-651.
Cahoon, C.K. and Libuda, D.E., 2019. Leagues of their own: sexually dimorphic features of
meiotic prophase I. Chromosoma. 128(3). pp.199-214.
Clift, D. and Schuh, M., 2019. Restarting life: fertilization and the transition from meiosis to
mitosis. Nature reviews Molecular cell biology, 14(9), pp.549-562.
Crane and et.al., 2020. Aurora A, meiosis and mitosis. Biology of the Cell. 96(3). pp.215-229.
Crickard, J.B. and Greene, E.C., 2018. The biochemistry of early meiotic recombination
intermediates. Cell Cycle. 17(23). pp.2520-2530.
Krude, T., 2019. Initiation of human DNA replication in vitro using nuclei from cells arrested at
an initiation-competent state. Journal of Biological Chemistry, 275(18), pp.13699-
13707.
Matos and et.al., 2019. Regulatory control of the resolution of DNA recombination intermediates
during meiosis and mitosis. Cell. 147(1). pp.158-172.
Paulson and et.al., 2021, September. Mitotic chromosomes. In Seminars in Cell &
Developmental Biology (Vol. 117, pp. 7-29). Academic Press.
Pervouchine, D.D., 2018. Towards Long-Range RNA structure prediction in eukaryotic
genes. Genes. 9(6). p.302.
Riley, R. and Law, C.N., 2020. Genetic variation in chromosome pairing. Advances in
genetics. 13. pp.57-114.
Srivastava, A. and et.al., 2020. Structure-guided DNA–DNA attraction mediated by divalent
cations. Nucleic acids research. 48(13). pp.7018-7026.
Xiao and et.al., 2021. The genetic mechanism of heterosis utilization in maize
improvement. Genome Biology. 22(1). pp.1-29.
Online
Gene heredity, 2021. (Accessed through) [Online]< https://www.britannica.com/science/gene>.

Chromosomes, 2021. (Accessed through) [Online] < https://www.toppr.com/guides/molecular-
genetics/chromosome/>.
Molecular mechanism of DNA replication, 2022. (Accessed through) [Online] <
https://www.khanacademy.org/science/ap-biology/gene-expression-and-regulation/replication/
a/molecular-mechanism-of-dna-replication#:~:text=DNA%20replication%20is
%20semiconservative%2C%20meaning,new%20and%20one%20old%20strand.>.
DNA, Structure, functions and discovery, 2021. (Accessed through) [Online]<
https://byjus.com/biology/dna-structure/>.