Download complete project materials on Construction Of A Model Of Meiotic Cell Division from chapter one to five
ABSTRACT
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This project is a construction of a mode1 of meiotic cell division. Meiosis result in two daughter cells each is having the same number of chromosomes as the parent. It is important for cell replacement, growth, genetic stability, regeneration and asexual reproduction the construction of a mode1 of meiotic cell division shows the steps involved in the cell division process.
Construction of all the stages involved in meiosis were carried out with the use of the following materials, cardboard, beads, wires, thread, needle and markers to represent the process in which the stage divides. The meiotic cell division was done to create more and easier method to study the stages in meiosis cell division without the use of microscope.
TABLE OF CONTENT
Content
Title Page
Declaration
Approval Page
Dedication
Acknowledgment
Table of content
Abstract
CHAPTER ONE
1.0 introduction
1.1 Aim
1.2 Objectives
1.3 Justification
HAPTER TWO
LITERATURE REVIEW
2.1History of meiosis
2.2 The role of meiosis
The essential principle underlying meiosis
2.2.1The first meiotic division
Metaphase
Anaphase
Telophase
2.3.1 Chiasmata
2.3.2 Meiosis occurs in the following curcustances
2.3.3 Regenerations
2.4 Occurrence in eukaryotic life cycles
2.4.1The gametic life cycle
2.4.2 The zygotic life cycle
2.4.3 The sporic life cycles
2.5 Significance of meiosis
2.5.1 The key features of meiosis are as follow
CHAPTER THREE
Materials And Methods
3.1 Sample Collection
Methodology
Cutting of the Cardboards
3.4 Gumming of Wire
3.5 Gummimg of Beads
3.6 sewing
HAPTER FOUR
4.0 Results
Anaphase I
CHAPTER FIVE
5.0 Discussion
5.1 Conclusion
Reference
CHAPTER ONE
1.0 INTRODUCTION
Meiosis is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them. This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi. Errors in meiosis resulting in aneuploidy are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities (Freeman, 2011).
In meiosis, DNA replication is followed by two rounds of cell division to produce four potential daughter cells, each with half the number of chromosomes as the original parent cell. The two meiotic divisions are known as Meiosis I and Meiosis II. Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated so that it consists of two identical sister chromatids, which remain held together through sister chromatid cohesion.
This S-phase can be referred to as “premeiotic S-phase” or “meiotic S-phase”. Immediately following DNA replication, meiotic cells enter a prolonged G2-like stage known as meiotic prophase. During this time, homologous chromosomes pair with each other and undergo genetic recombination, a programmed process in which DNA is cut and then repaired, which allows them to exchange some of their genetic information.
A subset of recombination events results in crossovers, which create physical links known as chiasmata (singular: chiasma, for the Greek letter Chi (X)) between the homologous chromosomes. In most organisms, these links are essential to direct each pair of homologous chromosomes to segregate away from each other during Meiosis I, resulting in two haploid cells that have half the number of chromosomes as the parent cell.
During Meiosis II, the cohesion between sister chromatids is released and they segregate from one another, as during mitosis. In some cases all four of the meiotic products form gametes such as sperm, spores, or pollen. In female animals, three of the four meiotic products are typically eliminated by extrusion into polar bodies, and only one cell develops to produce an ovum.
Because the number of chromosomes is halved during meiosis, gametes can fuse (i.e. fertilization) to form a diploid zygote that contains two copies of each chromosome, one from each parent.
Thus, alternating cycles of meiosis and fertilization enable sexual reproduction, with successive generations maintaining the same number of chromosomes. For example, diploid human cells contain 23 pairs of chromosomes including 1 pair of sex chromosomes (46 total), half of maternal origin and half of paternal origin. Meiosis produces haploid gametes (ova or sperm) that contain one set of 23 chromosomes.
When two gametes (an egg and a sperm) fuse, the resulting zygote is once again diploid, with the mother and father each contributing 23 chromosomes. This same pattern, but not the same number of chromosomes, occurs in all organisms that utilize meiosis (Hassold et al., 1980).
Meiosis begins with a diploid cell, which contains two copies of each chromosome, termed homologs. First, the cell undergoes DNA replication, so each homolog now consists of two identical sister chromatids.
Then each set of homologs pair with each other and exchange DNA by homologous recombination leading to physical connections (crossovers) between the homologs. In the first meiotic division, the homologs are segregated to separate daughter cells by the spindle apparatus. The cells then proceed to a second division without an intervening round of DNA replication. The sister chromatids are segregated to separate daughter cells to produce a total of four haploid cells.
Female animals employ a slight variation on this pattern and produce one large ovum and two small polar bodies. Because of recombination, an individual chromatid can consist of a new combination of maternal and paternal DNA, resulting in offspring that are genetically distinct from either parent. Furthermore, an individual gamete can include an assortment of maternal, paternal, and recombinant chromatids.
This genetic diversity resulting from sexual reproduction contributes to the variation in traits upon which natural selection can act (Bernstein and Bernstein, 2010).
Meiosis uses many of the same mechanisms as mitosis, the type of cell division used by eukaryotes to divide one cell into two identical daughter cells. In some plants, fungi, and protists meiosis results in the formation of spores: haploid cells that can divide vegetatively without undergoing fertilization. Some eukaryotes, like bdelloid rotifers, do not have the ability to carry out meiosis and have acquired the ability to reproduce by parthenogenesis (Bernstein and Bernstein, 2010).
Meiosis does not occur in archaea or bacteria, which generally reproduce via asexual processes such as binary fission. However, a “sexual” process known as horizontal gene transfer involves the transfer of DNA from one bacterium or archaeon to another and recombination of these DNA molecules of different parental origin (Bernstein and Bernstein, 2010).
Meiosis I and II are each divided into prophase, metaphase, anaphase, and telophase stages, similar in purpose to their analogous subphases in the mitotic cell cycle. Therefore, meiosis includes the stages of meiosis I (prophase I, metaphase I, anaphase I, telophase I) and meiosis II (prophase II, metaphase II, anaphase II, telophase II) ((Hassold et al., 1980).
Meiosis generates gamete genetic diversity in two ways:
Law of Independent Assortment. The independent orientation of homologous chromosome pairs along the metaphase plate during metaphase I & orientation of sister chromatids in metaphase II, this is the subsequent separation of homologs and sister chromatids during anaphase I & II, it allows a random and independent distribution of chromosomes to each daughter cell (and ultimately to gametes); and
Crossing Over. The physical exchange of homologous chromosomal regions by homologous recombination during prophase I results in new combinations of DNA within chromosomes.
During meiosis, specific genes are more highly transcribed. In addition to strong meiotic stage-specific expression of mRNA, there are also pervasive translational controls (e.g. selective usage of preformed RNA), regulating the ultimate meiotic stage-specific protein expression of genes during meiosis. Thus, both transcriptional and translational controls determine the broad restructuring of meiotic cells needed to carry out meiosis (Hassold et al., 1980).
1.1 AIM
To construct a model of meiotic cell division.
1.2 OBJECTIVES
- To identify the various stages of meiosis
- To construct a model of meisos for use as an instructional materials
1.3 JUSTIFICATION
Construction of a model meiotic cell division is useful to lecturers in the process of their lecture to produce a very easy method of teaching
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