MITOSIS
by Alimzhan Muxunov
Group M
16.10.2014
Lab partner: Gulzhan Belgibay
INTRODUCTION One of the vital processes, which are very important for cells’ life, is called cell division. There are two types of it called mitosis and meiosis. In this practical, we will focus on mitosis. Mitosis is a part of eukaryotic cell division cycle, when a nucleus divides into two new nuclei. Prokaryotic cell does not have nucleus, so mitosis does not occur there. According to Kent (2000) and Campbell (2009), mitosis consisted of four steps: Prophase, Metaphase, Anaphase and Telophase. Interphase is the preparation of cell to mitosis: growth of the cell and its’ organelles, replication of DNA occur during this period. Mitosis starts with prophase, when the chromosomes are coiled and become shorter, next stage is metaphase when chromosomes line
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Interphase is a preparation of the cell to mitosis, during interphase DNA duplicates, but chromosomes actually are not visible on this stage. Interphase requires for minimum 90% of the whole time of cell division (Campbell 2009, p.129). The first step of mitosis is a prophase, when chromosomes become more visible, nuclear membrane disappears, mitotic spindle forms in the cytoplasm and centrioles move to opposite sides of the cell (Kent 2000, p. 76). The next stage after this is metaphase, during which chromosomes line up at the equator of the cell, after that process spindle fibers attach to chromosomes from two opposite sides (Kent 2000, p. 76). The stage of separating paired chromosomes and their movement to the opposite poles of the cell is called anaphase (Kent 2000, p. 77).The last step of mitosis is telophase, during which new membranes of two daughter nuclei appear and chromosomes become less visible(Kent 2000, p. 76). Mitotic index, which is used when the growth of tumour in cancer patients is studied, was
Chromosome pairs line up across the equator of the spindle at metaphase I (5). In anaphase I the chromosomes separate and travel to opposite ends of the spindle. The chromosomes migrate to the equators of two new spindles for metaphase 2 (7). Next the chromatids are pulled apart in anaphase 2 to form four clusters of chromosomes in telophase 2. The nuclear envelopes reform around four haploid nuclei that will give rise gamete
Website to go for quizzes and activities: Print out the quizzes for mitosis and meiosis http://www.phschool.com/science/biology_place/labbench/
Out of a total from 26 sequences only 6 were made up of 4‘s while 20 were composed of different structures of 2‘s. This tells us that 77% of the asci showed crossing over while 23% did not.
Compare and Contrast Mitosis and Meiosis Meiosis and mitosis describes the process by which cells divide, either by asexual or sexual reproduction to produce a new organism. Meiosis is a form of cell division that produces gametes in humans these are egg cells and sperms, each with reduced or halved number of chromosomes. The number of chromosomes is restored when two gametes fuse together to form a zygote. A cell with two copies of each chromosome is called diploid cell and a cell with one copy of each chromosome is called a haploid cell.
Mitosis and meiosis are similar in several ways and different in others. The similarities include that both processes involve IPMAT. IPMAT is interphase, prophase, metaphase, anaphase and telophase. The parent cells are diploid. They both end with cytokinesis. In Metaphase and Metaphase II, the sister chromatids line up along the center. Then in Anaphase and Anaphase II, these chromatids are split and pulled towards the centrosomes. The differences are that mitosis consists of 1 division while meiosis consists of 2. Four genetically different, haploid sex cells are the products of meiosis and 2 identical, diploid somatic cells from mitosis. Mitosis occurs in all organisms except viruses and meiosis only occurs in plants, animals, and fungi.
A) Meiosis consists of two cell divisions and is broken up into Meiosis I and Meiosis II. At the beginning of the Cell Cycle, in this case there are four chromatids each from the homologous pairs being A, a, B, b. This is the Diploid number (4) meaning it is 2 times the haploid number that will be seen at the end of meiosis II. During the S phase of interphase, the chromatids replicate and reach the end of G2 phase. Now starting meiosis, during the first stage of prophase I the chromosomes condense and pair up through synapsis with their sister chromatids creating AA, aa, BB, bb. After they pair up they go through a process called crossing over, where the homologous chromosomes share a piece of their genetic material with each other. Crossing over allows for the genetic diversity of chromosomes. Now there are four homologous chromosomes Aa, Aa, Bb, Bb, each containing heterozygous alleles because the sister chromatids exchanged genetic information with their homologous pair. During late prophase I, spindle fibers being to form where they will later attach to a homologous chromosomes centromere. The next stage is Metaphase I. During metaphase I, the homologous pairs line up at the metaphase plate, also known to be the center of the cell. The homologous pairs form a tetrad which is considered a group of four homologous chromosomes. These homologous chromosomes orient themselves randomly, which is know as the process of independent
Although mitosis is just a fraction of time compared to interphase it can be divided into four distinct subphases. If we start viewing a cell under a brightfield microscope right at the end of interphase subphase G2 we would see that throughout the interphase process (fig 1) the cell has grown considerably in size due to production of extra mitochondria and endoplasmic reticulum. The cell has also gone through the labor of duplicating all of its chromosomes, a process known as DNA synthesis. Now that the cell has made all of these preparations it's time to start prophase (fig 2), the first stage of the mitotic phase. This stage is visibly identified by the chromatin becoming the tightly formed chromosomes. During the lab we were able to view these newly formed chromosomes best on the onion root tip
Anaphase – the chromosomes are divided into single from pair and the chromosomes move to opposite poles
The cell cycle is a series of stages that occurs when a new cells makes the division from the parent cell to two daughter cells. This is a stage in cellular reproduction. The cell cycle consists of three phases, interphase, mitosis, and cytokinesis. During Interphase, a cell will continue to perform its functions as usual. The time frame for Interphase varies; while an embryonic cell will take just a few hours to complete the cycle, a stem cell from an adult can take 24 hours (Mader, Windelspecht, 2015). After the interphase stage completes itself, a complete nuclear division happens and mitosis occurs. During the stage of mitosis, the daughter cells will receive the same amounts of the contents of the parent cell. Throughout the last stage, in the cytoplasm there is a division known as Cytokinesis (Mader, Windelspecht, 2015). Cytokinesis occurs differently in plant cells than it does in animal cells, as the cell wall around the plant prevents the process from happening the same way. Instead, a new plasma membrane and cell walls are built are built between the daughter cells. However, in animal cells a single cell will become two (Mader, Windelspecht, 2015).
17) The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called
Mitosis is the fourth stage of the cell cycle. It includes two phases mitosis and cytokinesis. Mitosis is the division of the cell's nucleus and all it’s contents. Cytokinesis is the process that divides the cell’s cytoplasm. The stages of the cell cycle and the proteins are all alike in all
Mitosis is one of two main methods of cell replication, the other being meiosis. It is “the simple duplication of a cell and all of its parts” resulting from the splitting of a cell. The ‘parent’ or original cell splits, duplicating its DNA (packaged in chromosomes) producing two ‘daughter’ or new cells with the same genetic code. There are four stages of mitosis; Prophase, Metaphase, Anaphase and Telophase. Interphase is not an official phase of mitosis as the cell is at ‘rest’ and not being divided during this phase. It is often called one of the phases of mitosis as it is one of the stages in the life cycle of a cell; however it is not a phase of mitosis due to the fact that no division takes place.
There are four stages of mitosis. The first stage is the prophase. In this stage the chromosomes become
In genetics, the way people retrieve their genes and traits is through cell division; mitosis and meiosis. Mitosis in cell division is the process in making body cells. There are 7 stages in mitosis; interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. In interphase, the cell is growing normally and synthesizes with organelles. In prophase, changes occur in the cell and parts of the structures begin to break down, setting the stage for chromosome division. Prometaphase is the stage where the chromosomes are sorted and made very compact, and metaphase is when the chromatids of each chromosome are attached to a microtube to form a spindle. Anaphase it the process in which the chromosomes split, leading into telophase, which is where the chromatids travel to opposite poles in a cell and new membranes form around the nuclei. The final stage in mitosis, cytokinesis, is when the chromatids split in two.
The main focus of this lab was to be able to understand the different phases of mitosis and the cell cycle and also identify what those stages may look like. Mitosis is the process in which concerns the production of new cells. For example, when apoptosis(cell death) the process of Mitosis begins to replace the dead cells. To be able to familiarize ourselves with this concept, we took a sample of an onion root and had it put through a process to be able to look at the different phases under the microscope. We found that the majority of the cells were mostly undergoing Interphase or Prophase which are the phases in charge of crossing over of DNA and where the chromosomes then become visible and the nuclear envelope dissipates. The conclusion of this lab was that Mitosis is essential for the production of new cells. In the case of the onion root sample, the cells were damaged leading to the tester to undergo Mitotic cell division and it was found that mainly Interphase and Prophase were the stages that occurred in this lab.