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I’m working on a biology writing question and need support to help me understand better.Student Learning Outcomesundefined undefined(1) Be able to list and identify the phases of a cell’s life cycle known as Prophase, Metaphase, Anaphase, Telophase and Interphase.undefined(2) Be able to draw a pie diagram indicating the relative proportions of time a plant, like Allium (onion), spends in the different mitotic phases.undefined(3) Be able to diagram and describe the stages of embryonic development common to all animals (zygote, morula, blastula, and gastrula).undefined(4) Be able to diagram and describe the function of a fertilization membrane surrounding a fertilized Sand dollar egg.undefined(5) Be able to contrast the end results of the 2 kinds of cell division observed in Eukaryotic cells: Mitosis and Meiosis.undefinedIntroductionundefinedThe tremendous diversity of structure and function that eukaryotic cells assume is remarkable when you consider that most multicellular organisms begin life as a single fertilized egg, the zygote. Through repeated divisions, this cell gives rise to all the cells that make up the organism. The series of events experienced during cell division by actively reproducing cells is termed mitosis. Mitosis also serves as the basic mechanism of reproduction in unicellular organisms. In this lab, you will examine several essential aspects of mitosis, and of the role of mitosis in the early development of multicellular organisms.undefinedMitotic processes are rather easily observed in situations where rapid increases in cell numbers are occurring. Two cell types that will be used in this lab are 1) the cells produced as a consequence of fertilization in the sand dollar, Dendraster, and 2) cells in the growing root tips of the onion, Allium.undefined I. Mitosis in PlantsundefinedAt no time other than cell division can a cell’s chromosomes be observed. Although it is also possible to see chromosomes during meiosis, today we will examine mitosis in a rapidly growing tissue, the root tip of the onion Allium. undefinedAlthough animal and plant cells differ somewhat in structure as well as in some of the fine points of mitosis, the mitotic phases are essentially the same in all eukaryotic cells. While the process is continuous and there is some gradation among the various steps, four general phases can be identified: Prophase, Metaphase, Anaphase, and Telophase. Mitosis is followed by cytokinesis, the division of the cell’s cytoplasm, which also takes the two new nuclei into separate daughter cells. When a cell in a growing tissue phase is not in mitosis, we say it is in Interphase (this phase is not regarded as one of the phases of mitosis). During this relatively long period, the DNA is replicated in the nucleus and extra amounts of other cellular components are synthesized, in preparation for distribution to future daughter cells. No evidence of this activity can be seen until the next mitosis, when the nuclear membrane dissolves and the chromosomes condense into the short, thick, stainable bodies which are visible through the light microscope.undefinedFor any given species, there is usually one characteristic number of chromosomes (n) found in the gametes and double that number (2n) found in cells of the sexually reproducing adult. There is wide variation in the number of chromosomes characteristic of species, and the n does not necessarily indicate how much hereditary material is present. In some species, there is a large n but the chromosomes are very small, while other species have fewer, larger chromosomes. The chromosomes of onion cells are large and relatively few (2n=14), making them easier to study than the cells of many other organisms. undefinedObservation of Mitotic Phases in Onion (Allium) Root Tip Cells
undefinedThe growing onion root tip is one of the most widely used materials for the study of mitosis, since it is easily cultivated in quantity and preparations of the dividing cells are easily made. There are regions of rapid cell division in root tips; therefore, the chances are good that within such tissues one can identify every stage in mitosis. The following study will involve an examination of preserved and stained thin sections of onion root tips, with the stains making the chromosomes of the cells quite visible.undefinedYou will need a microscope for this portion. Be sure to use two hands. Make sure that the cord is not dangling to prevent a tripping hazard. Before using the microscope, check for the condition the microscope was left in from the prior class. Requirements: N/A

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