Observation of Mitosis

bill of Mitosis Introduction Reproduction is the biological process by which new idiosyncratic organisms atomic chip 18 elicitd. There be twain types of reproduction, which are aintimate and intimate reproduction. Asexual reproduction is creation of offspring whose genes all come from virtuoso parent. Sexual reproduction is creation of offspring by amalgamation of phallic gametes (sperm) and female gametes (eggs) to form zygotes. Asexual reproduction involves a type of stall variation known as mitosis. Mitosis is the scientific term for nuclear kiosk division, where thenucleusof the electric cadre divides, resulting in two sets of identicalchromosomes.Mitosis is accompanied bycytokinesisin which the end result is two completely separate cells called miss cells. There are quadruplet phases of mitosis prophase,metaphase, anaphase and telophase. The active sites of cell division in plants are known as meristems and they are convenient source of mitotic cells for reflecti on under the light microscope. In this experiment two different methods had been used. single of the methods that harbour been used was Feulgen Reaction, root exploits have been fixed and stained exploitation this reaction.This histochemical method is specific for deoxyribonucleic acid which is stained deep red-purple. Aim investigate the stages of mitosis under light microscope. Method 1 Preparation of Root wedge and Observation of Mitosis in Garlic Root Meristems Firstly, virtuoso root consequence was taken from a container by using a pipette. This root tip was putted on a slide and a drop of 80% glycerine was added, than a c everywhereslip applied. After coverslip was applied, slide was covered with a sheet of blotting theme and squashed gently.Lastly this sample was observed under light microscope both with emit occasion and high power objective. Method 2 Observation of Mitosis in Allium SP. Root Meristems Slides of Allium sp. Root tip squashes was prepared and provid ed. These frame slides were observed under light microscope both low and high power objectives and stages of mitosis were drawn. Disscusion Meiosis has many similarities to mitosis. However, there are major disputes that it is essential to note. The gameboard below shows the comparison of the stages of mitosis and meiosis. Stages Meiosis MitosisInterphase begins with a diploid cell begins with a diploid cell Prophase four chromosomes combine to form two tetrads the chromosomes in the tetrad cross over each(prenominal) other, allowing them to exchange genetic worldly -four chromatids combine to form two chromosomes linked by a kinetochore Metaphase the two tetrads key up in the centre the two chromosomes line up in the centre Anaphase the two tetrads split up into four chromosomes which go to both poles the two chromosomes split up into four chromatids which propel to both of the poles Telophase the two sets of chromosomes become enclosed by the nuclear envelope t he two sets of chromatids are enclosed by the nuclear envelope Cytokinesis two cells are formed with two sets of chromosomes in each one cardinal cells are created with two chromatids in each one. Mitosis is now complete. Prophase II DNA replication is skipped and the two cells nuclear envelope are dissolved and the ear reformed the four chromatids in each cell are affiliated unneurotic to form two chromosomes Metaphase II the two chromosomes line up in the centre Anaphase II the two chromosomes are split up into their daughter chromatids and moved towards opposites poles Telophase II The nuclear envelope is reformed more or less the two poles on each cell. Cytokenesis the cells are split up over again and four haploid cells remain as a result meiosis is now complete The second table below shows the general difference between mitosis and meiosis. Mitosis Meiosis Produces body cells(Somatic cells) cells for g haggleth and repair Produces sex cells(Gametes) cells for sexual reproduction One nuclear division, separating chromatids Two nuclear divisions, first separating homologic chromosomes and second separating chromatids Two daughter cells produced Four daughter cells produced Chromosome number cadaver very(prenominal) Chromosome number halved No association between homological chromosomes homologous chromosomes associate and form bivalents No crossing over ccurs Crossing over many occur at chiasmata Chromosomes only form single row at equator at metaphase At metaphase 1, chromosomes form double row at equator Daughter cells genetically identical with each other and parent cell Daughter cells differ genetically from each other and parent cell Daughter cells have two sets of chromosomes(pairs) Daughter cells have only one member of each pair of chromosomes In metaphase chromosomes line up individually In metaphase I chromosomes line up as homologous pairs (synapsis). The two double chromosomes are called a tetrad when they are lined co mparison of the biological significance of mitosis and meiosis * The Significance of MitosisThe significance of mitosis is its ability to produce daughter cells which are exactly the same as the parent cell. It is significant for three reasons 1. Growth If a tissue wants to get bigger by growth needs new cells that are identical to the existing ones. Cells division must therefore be by mitosis. 2. Repair Damaged cells have to be replaced by exact copies of the organism so that it repairs the tissues to their former condition. Mitosis is the kernel by which this is achieved. 3. Asexual reproduction If a species is good at colonizing a habitat, there magnate be no point, in producing offspring which are different from the parents, because they might be less effective at survival.Therefore it might bebetter, in the short term,to make a colony which is similar to the parents. In simple animals and most plants this is achieved by mitotic division. * Significance of Meiosis The bulky term survival of a species depends on its ability to adapt to a changing environment. To do this the offspring need to be different from their parents and each other. These are three ways in which variety occurs because of meiosis. 1. Production and fusion of haploid gametes The variety of offspring is increased by mixing the genotype of one parent with that of the other. It involves the production of special sex cells, called gametes, which fuse together to produce a new organism.Each gamete contains half the number of chromosomes of the adult. It is important that meiosis, which halves the number of chromosomes in daughter cells, happens at some stage in the lifespan cycle of a sexually reproducing organism. Therefore Meiosis is important in order for variety in organisms, and allowing them to evolve. 2. The creation of genetic variety by the random distribution of chromosomes during metaphase 1. When the pairs of homologous chromosomes arrange themselves on the equator of the s pindle during metaphase 1 of meiosis, they do it randomly. Even though each one of the pair determines the same general features, theyre detail of the feature is different.The randomness of this distribution and strong-minded assortment of these chromosomes produces new genetic combinations. 3. The creation of genetic variety by crossing over between homologous chromosomes. During prophase 1 of meiosis, equal portions of homologous chromosomes may be swapped. In this way new genetic combinations are made and linked genes separated. The variety which meiosis brings vital for to the process of evolution. By providing a varied stock of individuals it allows the natural selection of those best suited to the existing conditions and makes sure that species constantly change and adapt when these conditions change. This is the main biological significance of meiosis. Gizem KARAGOZLU 19026857.