Mitosis And Meiosis

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

Exercise 3A is a study of mitosis. You will simulate the stages of mitosis by using chromosome models.You will use prepared slides of onion root tips to study plant mitosis and to calculate the relative duration of the phases of mitosis in the meristem of root tissue. Prepared slides of the whitefish blastula will be used to study mitosis in animal cells and to compare animal mitosis and plant mitosis.

Meiosis consists of one DNA replication and two nuclear divisions resulting in 4 daughter cells. The process which provides for genetic variation is crossing over. Crossing over occurs in the early stages when homologous chromosomes move together so that their chromatids form a tetrad. This is called synapsis and allows for the exchange of chromosome sections.

Mitosis: This is the process by which a cell duplicates the chromosomes in its cell nucleus in order to generate two identical daughter nuclei.

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 phase of mitosis proceeding anaphase in which two daughter cells are formed, their nuclei are formed, chromosomes unravel, and the cleavage furrow closes the gap between them and separates them (cytokinesis occurs).

17) The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

cell will look just like any other 'normal' cell although this is far from the

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.

Response Feedback: Meiosis occurs only in replicating gametes or reproducing cells. In phase one, the number of chromosomes is reduced by half but the chromatid pairs remain together. In phase two, the chromatids split apart forming four daughter cells. Non-germ cells such as red blood cells or skin cells undergo mitosis.For more information on this topic, consult:Carol Mattson Porth and Glen Matfin, Pathophysiology, 8th Edition,

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.